Posted: April 24th, 2025

HCI and UI – Discussion

Designing a usable interface can be challenging. One of the best ways to learn is to review interfaces and see where they deviate from convention. This week, we learn about 2 concepts: the 8 golden rules of interface design and methods of capturing the user’s attention.

For your discussion question this week, first, provide 3 examples of systems, computer interfaces, applications, or websites that violate some of those rules. For each example, explain what rules are violated and how you would fix them.

Second, provide 3 examples of interfaces that catch the user’s attention well when alerting them to an abnormal condition or time-dependent information. Explain other options that could have been used to accomplish the same result.

Need about 3 pages with peer-reviewed sources. No introduction or conclusion needed.

PART OUTLINE
Chapter 1: Usability of Interactive Systems

Chapter 2: Universal Usability

Chapter 3: Guidelines, Principles, and Theories

PART

mtnodu @t

Th is f irst set of chapters provides a broad introduc t ion to user interface des ign and interact ive
systems . Chapte r 1 covers usab ility goa ls, meas ur es, and motivations as well as gene ral goa ls
for the HCI profession. A r ich set of resources is available at the end of the chapte r, listing
impo rtant books, guideli nes, and relevan t jour nals and prof essional organiza tions.

Chapter 2 discusses universal usab il ity and exposure to the diversity of users. This includes
t he cha llenges posted by physica l, cognit ive, perceptual, personality, and cultu ral d ifferences.
Chapter 3 reviews t he guidel ines, pr inciples, and theor ies of the field to help facil itate good
design.

•

CHAPTER

Usa6ili ~ I mter.a@ti~e
S)jsferilils

99 Designing an object to be simp le and clear takes at least twice
as long as the usual way. It requires concentration at the outset on
how a clear and simp le system would work, followed by the steps

required to make it come out that way-steps which are often much
harder and more complex than the ordinary ones. It also requires

relentless pursuit of that simp licity even when obstacles appear
which would seem to stand in the way of that simplicity . ”

CHAPTER OUTLINE
1. 1 Introduction

1.2 Usability Goals and Measures

1.3 Usability Motivations

1.4 Goals for Our Profession

T. H. Nelson
The Home Computer Revolution , 1977

25

26 Chapter 1 Usability of Interactive Systems

1 . 1 Introduction

User -interface designers are the heroes of a profound transformation. Their
work turned personal computers into today’s wildly successful mobile devices,
enabling users to communicate and collaborate in remarkable ways. The desk­
top applications tha t once served the needs of professionals have increasingly
given way to powerful social tools that deliver compelling user expe riences to
global communities. These invigorated communities conduct business, commu ­
nicate with family, get medical adv ice, and create user-generated content that
can be shared with billions of connected users.

These life-changing shifts were made possible because researchers and user ­
interface designers harnessed technology to serve human needs . Resea rchers
created the interdisciplinary design science of hu1nan-compitter interaction by
applying the methods of experimental psychology to the powerful tools of com­
puter science. Then they integrated lessons from educational and industrial psy­
chologists, instruc tional and graphic designers, technica l writers, experts in
human factors or ergonomics, and growing teams of anthropologists and soci­
ologists. As the impact of these mobile social tools and services spreads,
researchers and designers are gathering still fresher insights from sus tainability
activists, consumer advocates, citizen scientists, and humanitarian disaster
response teams.

User experience designers produce business success stories, Hollywood
heroes, and Wall Street sensations. They also produce in tense compe tition,
copyright-infringemen t su its, inte llectual-proper ty battles, mega-mergers, and
international partnerships. Crusading Internet visionaries, like Google’s Eric
Schmidt, promote a world with free access to information and ente rtainment,
while equally devoted protec tors of creative ar tists, like singer Taylor Swift,
argue for fair payments. User in terfaces are also controversial because of their
central role in persona l identification, national defense, crime fighting, elec­
tronic health records, and so on.

At an individual level, effective user experiences change people’s lives: Doc­
tors can make more accura te diagnoses, ai,d pilo ts can fly airplanes more safely;
at the same time, children can learn more effective ly, users with disabilities can
lead more productive lives, and graphic artists can explore more creative possi­
bilities . Some changes, however, are disrup tive, reducing the need for telephone
operators, typesetters, and travel agents . Too often, users must cope wi th frus­
trat ion, fear, and failure when they encounte r excessive ly complex menus,
incomprehensible terminology, or chaotic navigation paths.

At a societa l level, connected communities open up new forms of colJective
action and policy engagement. Having more informed citizens may lead to be t­
ter decis ions, more transpare nt governance, and greate r equity when facing

1.1 Introduction 27

legal, health, or c1v1c challenges. But there may be increased dangers from
extreme groups who promote terrorism, oppressive social policies, or racial
hatred. The increased power of social media and collaboration technologie s
means that there must be a new balai1ce of legal protections, police powers, and
privacy.

The steadily growing interest in human-computer interaction stems from
the designers’ desire to improve the users’ experience (Figs. 1.1 to 1.3 show
some popular applications). In busine ss settings, better decision-support and
document-sharing tools support entrepreneurs, while in-home settings, digital
photo libraries, and internet conferencing enhance family and personal
relationships. Millions of people take advantage of the World Wide Web’s
extraordinary educational and cultural heritage resource s, which provide
access to everything from outstanding art objects from China to music from
Indonesia, sports from Brazil, and entertainment from Hollywood or Bollywood

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Left: Goog le Now for searching, reviewing notification cards, and speaking commands.
Center: Zombies, Run! is an immersive running game and audio adventure which
encourages runners to run as if pursued by zoombies, and to collect goods to help
their community survive.
Right : A Twitter feed lists the top tweets after Ben Shneiderman announced the
release of the HCI Pioneers website.

28 Chapter 1 Usability of Interactive Systems

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Apple ® Mac OS X®. showing Picasa for photo browsing and Google Maps in a web
browser. The bottom of the screen also shows the Dock, a menu of frequently
accessed items whose icons grow larger on mouse-over.

(Figs. 1.4 to 1.5 show examples of popular websites). Mobile devices enrich
daily life for many users, including those with disabilities, limited literacy, and
low income s. On a worldwide
scale, promoter s and opponents
of globalization debate the role
of technology in international
development, whil e activists
work to attain the Unjted
Nations Sustainable Develop­
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The remarkably rapid and
widespread adoption of mobile
devices (including smartphones,
tablet s, game devices, fitness tra­
ckers, etc.) supports personal
communication, collaboration,
and content creation. The
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two high-resolution screens. We can see a
MS Word document (wi th six pages visib le),
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app lication in a Windows environment.

1.1 Introduction 29

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nations has been astonishing. Economists see a direct linkage between cell­
phone dissemination and econom ic growth since communications facilitate
e-commerce and stimulate entrepreneurial ventures. Mobile devices also
promote wellness, enable timely medical care, and provide life-saving disaster
response services.

Similarly, explosive growth is the appropriate description for what's happen­
ing in the realm s of social networking and user-generated content. Older media,
such as newspapers and television, have lost audiences in favor of social media
such as Facebook, Twitter, YouTub e, and Wikipedia (all of which are among the
top 10 most visited services). These leading websites are just a taste of what is to
come, as entrepreneurs trigger ever more social media involvement accessible
through web-based applications and small mobile de vices .

Designers e11able users to create, edit, ai1d distribute 3-D printed objects,
imrnersive virtual reality games, interactive animations, and increasingly high­
definition music, voice, and videos. The result is ever-richer experiences and a
creative outpouring of user-generated content available, even on mobile
devices.

30 Chapter 1 Usability of Interactive Systems

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only t he flights landing before 10:25 P.M.

32 Chapter 1 Usability of Interactive Systems

Designers are already offering interfaces that are wearable or control implanted
(under-the-skin) devices, such as pacemakers, insulin pumps, and varied bio­
monitors. Other kinds of sensors already track FedEx packages, users entering
buildings, or cars at tollbootl1s, but they will expand into elaborate sensor 11ets
that follow crowds, epidemics, and pollution.

Other designers promote persuasive technologies that change users’ behav­
ior, multi-modal or gestural interfaces that facilitate use, and affective interfaces
that respond to the user’s emotional state.

We are living in an exciting time for designers of user interfaces. The inspira­
tional pronouncements from technology prophets can be thrilling, but rapid
progress is more likely to come from those who do the hard work of tuning
designs to ge11uine human needs. These designers will rigorously evaluate
actual use with eager early adopters, as well as reluctant late adopters, and seri­
ously study the resistant non-users. This book’s authors believe that the next
phase of human-computer interaction will be strongly influenced by those who
are devoted to broadening the community of users by promoting universal
usability and facilitating many forms of social media participation. User inter­
faces that deliver excellent user experiences will be a key component in improv ­
ing healthcare, creating sustainable economies, protecting natural resources,
and resolving conflicts (Froeh lich et al., 2010; Friedman et al., 2014).

This first chap ter gives a broad overview of human-computer interaction
from practitioners’ and researchers’ perspectives. It lays out usability goals,
measures, and motivations in Sections 1.2 and 1.3 and closes with a statement of
goals for our profession. Specific references cited in the chapter appear at the
end, followed by a set of general references. Lists of relevant books, guidelines
documents, journals, professional organizations, and video collections give
readers starting points for further study.

The second chapter takes on universal usability, reminding readers of the
opportunities to reach diverse users with tailored materials that serve the needs
of young and old, high and low literac y users, diverse international users, and
users with varying disabilities.

The third chapter reviews the guidelines, principles, and theories that \-vill be
drawn on and refined thr oughout the book. Chapters 4- 6 introduce design pro­
cesses and evaluation methods, with case study examples to demonstrate the
processes and methods. Chapters 7-9 cover interaction styles that range from
graphical direct manipulation to speech control and their implementation using
common interaction devices . Collaboration is included in this part to emphasize
the need for every designer to go beyond the personal comp uter and consider
the many forms of social computing. Chapters 10-1 6 address the critical design
decisions that often determine the success or failure of products and that may
lead to breakthroughs that open the way to new possibilities. The Afterword
reflects on the societal and individual impacts of technology.

1.2 Usability Goals and Measures 33

1.2 Usability Goals and Measures

Every designer wants to develop high-quality user experiences that are admired
by colleagues, celebrated by users, and imitated by competitors. But getting
such attention takes more than flamboyant promises and stylish advertising; it’s
earned by providing quality features such as usability, universality, and useful­
ness. These goals are achieved by thoughtful planning, sensitivity to user needs,
devotion to requirements analysis, and diligent testing, all while keeping within
budget and on schedu le.

Managers who pursue user-interface excellence first select experienced design ­
ers and then prepare realistic schedules that include time for requ iremerlts gather­
ing, guidelines preparation, and repeated testing. The designers begin by
determining user needs, generating multiple design alternatives, and conducting
extensive evaluations (Cllapters 4-6). Modem user-interface-building tools then
enable implementers to quickly build working systems for further testing.

Successful designers go beyond vague notions of “user friendliness,” “intui­
tive,” and “natura l,” doing more than simply making checklists of subjec tive
guidelines. They llave a thorough u11derstanding of the diverse community of
users and the tasks that must be accomplished. They study evidence-based
guidelines and pursue the research literature when necessary. Great designers
are deeply comm itted to enhancing the user exper ience, which strengthens their
resolve when they face difficult choices, time pressures, and tight budgets. Great
designers are also aware of the importance of eliciting emotional responses,
attracting attention with animations, and playfully surpr isin g users.

When managers and designers have done their jobs well, their int erfaces gen­
erate positive feelings of success, compe tence, and mastery among users. The
users have a clear mental model of the interface that enables them to confidently
predict what will happen in response to their actions. In the best cases, the inter­
face almost disappears, enabling users to concentrate on their work, explora­
tion, or pleasure. This kind of calming environmen t gives users the feeling that
they are “in the flow/’ operating at their peak, while attaining their goals.

Close interaction with the user community leads to a well -chosen set of
benchmark tasks that is the basis for usability goals and measures. For each user
type and each task, precise measurable objectives guide the designer through
the testing process. The ISO 9241 standard Ergonornics of Human-System Interac­
tion (ISO, 2013) focuses on admirab le goals-effectiveness, efficiene1;1 and
satisfaction-but the following usability measures, which focus on the latter two
goals, lead more directly to practical evaluation:

l. Ti1ne to learn. How long does it take for typical members of the user
community to learn how to use the actions relevant to a set of tasks?

34 Chapter 1 Usability of Interactive Systems

2. Speed of perforniance. How long does it take to carry out the benchmark
tasks?

3. Rate of errors by users. How many and what kinds of errors do people make
in carrying out the benchmark tasks? Although time to make and correct
errors might be incorporated into the speed of performance, error handling
is such a critica l component of in terface usage that it deserves extensive
study.

4. Retention over time. How well do users maintain their know ledge after an
hour, a day, or a week? Retention may be linked closely to time to learn, and
frequency of use plays an important role.

5. Subjective satisfaction. How much did users like using various aspects of the
interface? The answer can be ascertained by interviews or by written sur­
veys that include satisfaction scales and space for free-form comments.

Every designer would like to succeed in e,rery measure, but there are often
forced tradeoffs . If lengthy learning is permi tted, task-performance times may
be reduced by use of abbreviations, hidden shortcuts, and compact designs that
minimize scrolling. If the rate of errors is to be kept extremely low, speed of per ­
formance may ha, re to be sacrificed. In some applications, subjective satisfaction
may be the key determinan t of success; in others, short learning times or rapid
performance may be paramount. Project managers and designers who are aware
of the tradeoffs can be more effective if they make their choices explicit and pub ­
lic. Requirements documents and marketing brochures that make clear whjch
goals are pr imary are more likely to be va lued.

After multip le design alternatives have been raised, the leading possibi lities
should be reviewed by designe rs and users . Low -fidelity paper mockups are
useful, but high-fidelity interactive prototypes create a more realistic environ­
ment for expert reviews and usability testing. The user training and supporting
materials such as online help can be produced before the implemen tation to
provide another review and a new perspect ive on the design. Next, the imp le­
mentation can be carried out with proper software tools; this task should be a
modest one if the design is complete and precise. Then, acceptance testing certi­
fies that the delivered interface mee ts the goals of the designers and customers.
Final ly, continuous evaluation an d improvement have become common prac ­
tices. These design processes, evaluation procedures, and software tools are
described more fully in Chapters 4-6.

The busiI1ess case for usability is strong and l1as been made repeated ly (Bias
and Mayhew, 2005; Tullis and Albert, 2013). User-interface design success sto­
ries can also be managerial success stories for projects that are on budget and on
schedule. A thoroughly documented set of user needs clarifies the design pro­
cess, and a carefully tested prototype generates fewer chai1ges durit1g
implemen tation while avoiding costly updates after release. Thorough accep­
tance testing of the implementation produces robust interfaces that are aligned

1.3 Usabi lity Motivations 35

with user needs. Then continuous evaluation based on usage logs and user com­
ments guide evolutionary refinements.

1.3 Usability Motivations

The enormous interest in interface usability arises from the demonstration of the
benefits that come from well-designed user interfaces. This increased motiva­
tion emanates from designers and managers of consumer electronics who pro ­
duce mobile devices, e-commerce websites, and social media where excellent
user experiences are necessary to succeed in large, highly competit ive markets.
Usability has gone from desirable to necessary for survival. Similarly, the huge
interest in games and entertainment has raised the performance of devices, net­
works, and user interfaces. The goals are to ensure that game playing is fluid
and vivid; that photo, music, and video streaming is fast; and that sharing is
graceful and simp le. Strong motivations for usability quality come from high­
functioning professionals who demand excellence in environments such as life­
critical systems, industrial plants, legal offices, and police agencies. The spirit of
usability excellence is also expected by users of exploratory, creative, and col­
laborative interfaces as well as diverse sociotechnical systems.

1.3. l Consumer electronics, e-commerce, and social media

User experience designers have played a key role in the dramatic growth of con­
sumer electronics by providing effective and satisfying designs that have
become widely adopted for personal communications, education, healthcare,
and much more. The annual Consumer Electronics Show, now replicated in
many locations around the world, brings tens of thousands of exhib itors and
hundreds of thousands of at tendees who are eager to try the latest products
from leading vendors.

Produ ct announcements trigger worldwide media coverage, with Hollywood
or sports personalities celebrating the newest products. Similarly, famed musi­
cians, supermodels, and other luminaries contribute to the media hype while
making everyone aware of the latest designs, appealing features, and must-have
capabilities. Heroes such as Apple’s Chief Design Officer Jony Ive have become
celebrities who are knighted by the Queen of England and pestered by inter­
viewers to reveal the secrets of the next product release.

The transformative power of consumer electronics has been celebrated by
those who see improved family communication, better healthcare, thriving
businesses, and wider access to education. The social media applications, domi­
nated by Facebook, and user-generated content such as online restaurant, film,
or product reviews have become part of daily life for many users. For these

36 Chapter 1 Usability of Interactive Systems

interfaces, ease of learning, low error rates, and subjective satisfaction are para­
mount because use is discretionary and competition is fierce. If the users cannot
succeed quickly, they will give up or try a competing supplier. Critics raise con­
cerns about reduced privacy, dangers in distracted dri ving, and declinit1g
qua lity of interpersonal relationships.

1.3.2 Games and entertainment

The rapid expansion of home and entertainme11t applications is a further source
of interest in usability. Personal-computing applications include e-mail clients,
search engines, cellphones, digital cameras, and music players. Entertainment
applications have flourished, making computer games a larger industry than
Hollywood, while game input devices like the Nint endo ® Wii™ and the Microsoft
Kinect’s™ contro ller -free gameplay (Fig. 1.8) open up entirely new possibilities
in areas ranging from sports to education to rehabilitation.

Choosing the right functionality \-vhile keeping costs low is difficult. Novices
are best served by a cons train ed , simp le set of actions, but as users’ exper ience
increases, so does their desire for more extensive functionality and rapid
performance. A layered or leve l-structured design is one approach to facilitating
graceful evolution from novice to expert usage: Users can move up to higher
layers when they need additional features or have time to learn them. A simpl e

FIGURE 1.8
Dance Central, a highly successfu l dance-playing franchise of games in which users
dance to popular songs and earn points for how well they keep up. The Dance
Centra l website al lows users to purchase add iti onal songs and also hosts livestream
events and community forums.

1.3 Usabi lity Motivations 37

example is the design of search engines, which almost always ha ve basic and
advanced interfaces (Chapter 15). Another approach to winning novice users is
to carefully trim the features to make a simple device or application so users can
get star ted easily.

1.3.3 Professional environments

Most consum er electronics users a lso benefit from interfaces in professional
environments from sup ermarkets to space sta tions . Life-critical systems include
those that contro l air traffic, nuc lear reactors, power uti lities, police or fire dis ­
patch, mi litary operations, and clinical care (Fig. 1.9). In these applications, high
costs are expected, but they should yield high reliability and effectiveness.
Lengthy training periods are acceptable to obtain rapid, error-free performance,
even when the users are under stress. Subjective satisfaction is less of an issue
because the users are well-motivated professionals. Retention is obtained by fre­
quent use of common functions and practice sessions for emergency actions.

Typical industrial and commercial uses include interfaces for banking, insur-

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ance, produc tion management, air­
line and hotel reservations, tttility
billing, and point-of-sale terminals.
In these cases, costs shape many
judgments. Operator training time
is expensive, so ease of learning is
important. Since many businesses
are international, translation to
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The Wand t imeline view of a patient record
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Record iPad app lication .

jective satisfaction is of modest
importance; retention is obtained
by frequent use. Speed of perfor­
mance is central for most of these

· applications because of the high
volume of transactions, but opera ­
tor fatigue, stress, and burnout are
legitimat e concerns. Trimming
10% off the mean transaction time
could mean 10% fewer operators,
10% fewer workstations, and a 10%
reduction in hardware costs.

38 Chapter 1 Usability of Interactive Systems

1.3.4 Exploratory, creative, and collaborative interfaces

An increasing fraction of computer use is dedicated to supporting open-ended .
exploration that promotes human creativity while lowering barriers to collabo­
ration. Exploratory app lications include web browsers, search engines, data
visualization, and team collaboration support. Creative applications include
design environments (Fig. 1.10), music-composition tools, animation builders,
and video-ed iting systems. Collaborative interfaces enable two or more people
to work together (even if the users are separated by time and space) through use
of text, vo ice, and video; through systems that facilitate face-to-face meetings;
through large audience participation in webinars; or through sharing tools that
enable remote collaborators to work concurrently on a document, map, calen­
dar, or image.

In these exploratory, creative, and collaborative environments, the users may be
knowledgeable in the task domains but novices in the underlying computer con­
cepts. Their motivation is often high, but so are their expectations. Benchmark
tasks are more difficult to describe because of the exploratory nature of these appli­
cations, and usage can range from occasional to frequent. In short, it is difficult to
design and evaluate these systems. Designers can pursue the goal of having the

l .W:ode-st: SU-tch8ooli: Pfo sage ~.tlf O 37 1 ~

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FIGURE 1.10

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– charect•rs

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,. ···. ‘t’ftt •.•

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Ii

Sketchbook™, a design tool for digital artists, from Autodesk™. A large number
of tools and options are ava ilable through a rich set of menus and tool palettes
(http ://www.s ketchbook.co m).

1.3 Usability Motivations 39

computer “vanish” as users become completely absorbed in their task domains.
This goal seems to be met most effectively when the computer provides a direct­
manipulation repre sentation of the world of action (Chapter 7), supplemented by
keyboard shortcuts. Then tasks are carried out by rapid familiar selections or ges­
tures with immediate feedback and new sets of choices. Users can keep their focus
on the task with minimal distraction caused by operating the interface.

1.3.5 Sociotechnical systems
A growing domain for usability is in social systems that involve many people
over long time periods, such as healthcare, citizen science, disa ster response,
and community crime reporting. Int erfaces for these system s, often created by
governmental organizations, have to deal with trust, privacy, and responsibility
as well as limiting the harmful effects of malicious tampering, deception, and
incorrect information. Users will want to know whom to turn to when things go
wrong-and maybe whom to thank when things go right (Whitworth and de
Moor, 2009).

For example, in electronic voting systems (Jones and Simons, 2012), citizens
need to have reassuring feedback that their votes are correctly recorded, possi­
bly by having a printed receipt. In addition, government officials and profes­
sional observers from opposing parties need to have way s of verifying that the
votes from each district and regional aggregations are correctly reported
(Fig. 1.11). If complaints are registered, investigators need tools to review proce­
dures at every stage.

I Mid’l&el Hantto11

1 .. .. . ,,..,,

~ e..c.k , 1

F GURE 1. 11

Cancel ~ w votH

,.&~t llUI Patty

,..a t lectl-, No¥ 6, 20 12, St. Luc» COUI\OtV, Fl

ot:e Visualization for PRESIDENT AND VICE PRESIDENT:Barack Obama/Joe
Blden -·

ast Confident Votes for PRESIDENT AND VICE PRESIOENT:Ba(8(:k Obama/Joo Bl den

ef ‘.ib]r,J ~_0 c:p_ c”i~ @)@ •~ e w ~ ~ ~
1
s

~~rog~0~®~.~~~ c ~~d~~
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~ 0~ro@~©~ ~ 0e?0~ 00
¢ (ZS ct GZ> cii ~ ~~clil (0

On the left we see an examp le of a touchscreen voting kiosk interface (Summers et
al., 2014). We see contest number 2 out of 10 and the five candidates. The selected
candidate is clear ly marked. Some voting jurisdictions use paper ballots that are
then digitized. The interface on the right allows rapid review of al l the handwritten
marks. Courtesy of Clear Ballot (http://www.clearballot.com).

40 Chapter 1 Usability of Interactive Systems

Designers of sociotechnical systems have to take into consideration the diverse
levels of expertise of users with different roles. Successful designs for the large
number of novice and first-time users emphasize ease of learning and provide the
feedback that builds trust. Desigt1S for professional administrators and seasoned
investigators enable rapid performance of complex procedures, perhaps with
visualization tools to spot unusual patterns or detect fraud in usage logs.

1 .4 Goals for Our Profession

Clear goals are usefttl not only for interface design but also for educational and
professional enterprises. Three broad goals seem attainab le: (1) influencing aca­
demic and business researchers; (2) providing tools, techniques, and knowledge
for commercial d.esigners; and (3) raising the user-interface consciousness of the
general public.

1.4.1 Influencing academic and business researchers
Researchers in human-computer interaction are prolific as they produce more
than 10,000 papers per year. Their research include traditional controlled exper­
imentation in laboratory settings, but increasingly researchers conduct online
testing with real users, ethnographic observations in users’ homes or work ­
places, and long-term, in-depth case stud ies of users (Chapter 5).

Newer research methods include crowd-sourced user sh.tdies that invite thou ­
sands of users to participate or pay users through systems such as Amazon’s
Mechanical Turk. Another innovation is the use of user log data, observations,
and interviews to provide complemen tary strategies that reveal actua l perfor­
mance in live settings. The combination of methods often leads to a deeper under­
standing of the ftmdamental principles of human interaction with computers.

The classic scientific method for interface research, which is based on con­
trolled experimentation, has this basic outline:

• Understanding of a practical problem and related theory

• Lucid statement of a testable hypothesis

• Manipulation of a small number of independent variables

• Measurement of specific dependent variabl es

• Careful selection and assignment of subjects

• Control for bias in subjects, procedures, and materials

• Application of statistical tests

• Interpretation of results, refinement of theory, and guidance for experimenters

1.4 Goals for Our Profession 41

\Alhen experimental materials and methods are tested by pilot studies and
results validated by replication in various situations, then the recommendations
are more likely to be reliable.

Of course, the scientific method based on controlled experimentation has its
weaknesses. It may be difficult or expensive to find adequate subjects, and labo­
ratory conditions may distort the situation so much that the conclusions have
little value. Controlled experiments typically deal with short-term usage, so
understanding long-term co11sumer behavior or experienced user strategies is
difficult. Since controlled experiments emphasize statis tical aggregation,
extremely good or poor performance by individuals may be overlooked. Fur­
thermore, anecdotal evidence or researcher insights may be given too little
emphasis because of the authoritative influence of statistics.

Because of these concerns, researchers balance controlled experimentation
with ethnographic observation methods and long-term, in-depth case studies.
Anecdotal experierlces and subjective reactions are recorded, think-aloud
approaches are employed, and field or case studi es can be carried out. Other
research methods include crowd-sourced user studies, analysis of user logs, sur­
veys, focus groups, and interviews.

Within computer science and information studies, there is a growing aware­
ness of the need for greater atten tion to usability issues. Courses on human­
compu ter interaction are required for some undergraduate degrees, and
interface design issues are being added to many curricula. Researchers who pro­
pose new programming languages, privacy -protection schemes, or network ser ­
vices are more aware of the need to align with human cognitive skills and
preferences. Designers of advanced graphics systems, 3-D printing tools, or con­
sumer products increasingly recognize that their success depends on the con­
struction of effective user interfaces and creation of appealing user experiences.

There is a grand opportunity to apply the knowledge and techniques of tradi­
tional psychology (and of subfields such as cognitive and socia l psychology) to
the study of human-computer interaction. Psychologists are investigating
human problem solving and creativity with user interfaces to gain an under­
standing of cognitive processes and social dynamics. The benefit to psychology
is great, but psycho logists also have a golden opportunity to dramatically influ­
ence an important and widely used technology. Similarly, sociologists and com­
munications theorists are now actively participating in human-computer
interaction research.

Researchers in business, management, education, sociology, anthropology,
and other disciplines are benefiting from and contributing to the study of
human-computer interaction. There are many fruitful directions for research,
but here are a few:

• Reduced anxiety and fear of computer usage. Although compu ters are widely
used, some othen ,vise competent people resist using e-mail and engaging in
e-commerce because they are anxious about-or even fearful of-breaking

42 Chapter 1 Usability of Interactive Systems

the device, making an embarrassing mistake, or having their pri,,acy vio­
lated. Fear of scams and frustration with e-mail spam could also be reduced
by improved designs that promote security and privacy while increasing the
users’ control over their experiences.

• Graceful evolution. Although novices may begin their interactions with a computer
by using just a few features, they may later wish to move up to more powerful
facilities. Refined multi -layer interface designs, preference settings, and training
materials are needed to smooth the transition from novice to knowledgeable
user to expert. The differing requirements of novices and experts in terms of
prompting, error messages, online assistance, display complexity, pacing, and
informative feedback all need investigation . Users may be allowed to cus tomize
their interfaces far beyond changing backgrounds, font sizes, and ring tones, but
methods for guiding users through such processes are an open topic.

• Social niedia. The remarkable spread of social media is an indicator of larger
changes to come. Enabling sharing of user-genera ted content, especially from
mobile devices, is widespread; much work remains to be done in raising the
quality of what is produced, enabling effective annotations, making these
materials accessible, and facilitating reuse in ways that protect users’ desires
for privacy or profit.

• Input devices. The plethora of input devices presents opportuni ties and chal­
lenges to interface designers (Chapter 10). There are heated discussions abou t
the relative merits of multi -touch screens, voice, gestures, and haptic feed ­
back. Such conflicts could be resolved through experimentatio n with multi ­
p le tasks and users. Under lying issues include speed, accuracy, fatigue, error
correction, and subjective satisfaction.

• Information exploration. As navigation”, browsing, and searching in multimedia
digi tal libraries and the Wor ld Wide Web become more common, the pres­
sure for more effective strategies and tools has increased (Chapter 15). Users
will want to filter, select, and restructure their information rapidly with mini­
mum effor t and withou t fear of getting lost or finding misleading informa tion.
Large da tabases of text, images, graphics, sound, video, and scientific data,
commonly called big data, are becoming easier to explore with information
visualization and visual analytic tools.

1.4.2 Providing tools, techniques, and knowledge for
commercial designers

User -interface design and deve lopment are hot topics, and international compe ­
tition is lively. Employers who used to see usability as a secondary topic are
increas ingly hiring user exper ience designers, information architects, mob ile
app implemen ters, and usabili ty testers . These employers recognize the

1.4 Goals for Our Profession 43

competitive advantage from high-quality consumer interfaces and from improv­
ing the performance of their employees. There is a great thirst for knowledge
about software tools, design guidelines, and testing techniques. User-interface­
building tools provide suppor t for rapid prototyping and iI1terface development
while aiding design consistency, supporting universal usability, and simplify­
ing evolutionary refinement.

Guidelines documents have been written for general and specific audiences
(see the list at end of this chap ter). Most projects take the productive route of
writing their own guidelines, which are tied to the problems of their application
environments and users. These guidelines are constructed from experience with
existing interfaces, research results, and knowledgeable guesswork.

lterati, re usability testing and expert reviews are appropriate during interface
design. Once the initial iI1terface is available, contiI1uous refinements can be
made on the basis of observations, surveys, interviews, usage log analysis, or
more controlled empirical tests of novel strategies (Chapter 5). Agile processes
emphasize lively design studi o critiqu es of proposals and rapid trials of multi­
ple alternatives to guide designers.

Feedback from users during the design process and for continuous refine­
ment can provide useful insights and guidance. E-mail, web -based tools, and
text messaging allow users to send commen ts directly to the designers, while
logs of user behaviors provide designers w ith further evidence of what needs
fixing. While searchable databases of user questions can often resolve problems
and guide designers, online user consultants and fellow users can provide assis ­
tance and supportive encouragement.

1.4.3 Raising the user-interface consciousness
of the general public

The media are so filled with stories about user interfaces that raising public con­
sciousness of these tools may seem unnecessary . However, many people are still
uncomfortable witl1 the technologies they use. When they use a bank machine, a
cell phone, or e-mail, they may feel fearful of making mistakes, anxious about
damaging the equipment, worried about feeling incompetent, or threatened by
the computer “being smarter than I am.” These fears are generated, in part, by
poor designs tl1at have complex features, inconsistent terminology, confusing
error messages, and tortuous sequences of actions.

One of our goals is to encourage users to translate their internal fears into
outraged action. Instead of feeling guilty when they get a message such as
DATA ERROR, users should express their anger at the user-interface designer
who was so inconsiderate and thoughtless. Instead of feeling inadequate or fool­
ish because they cannot remember a complex sequence of actions, they shou ld
compla in to the designer who did not provid .e a more conven ient mechanism or
should seek another product that does.

44 Chapter 1 Usability of Int eractive Systems

Usabili ty ultimately becomes a question of national priorities. Advocates of
electronic voting and other services and promoters of e-healthcare and e-leaming
increasingly recognize the need to influence allocation of government resources
and commercial research agendas. Policymakers and industry lead ers become
heroes when they facilitate access and promote quality, but they become villains
when failures threaten children, disrupt travel, or menace consumers.

As examples of successful and satisfying interfaces become more visible, the
crude designs appear archaic and will become commercial failures. As design­
ers improve the user experience, some users’ fears wi ll recede, and the positive
experiences of their competence, mastery, and satisfaction will flow in.

Practitioner’s Summary

When designers of interactive systems cond uct thorough u ser and task analyses,
the y are more likely to gain insights that w ill lead them to a proper functional
design. They are more likely to have positive outcomes if they pay attention
to reliability, availability, security, integrity, standardi zation, portability,
integrat ion, and the administrative issues of schedules and budgets. As d.esign
alternatives are proposed, evaluations can lead to shorter learning times, more
rapid task performance, lower error rates, easier retention, and higher user
satisfaction. Designers who accommodate the needs of children, older adults,
and users with disabilities can improve the quality for all users. As designs are
refined and implemented, evaluation by pilot studies, expert reviews, usability
tests, user observations, user log analysis, and acceptance tests can accelerate
improvement. Success in product design is measured in terms of evidence that
universal usability is being attained (rather than testimonials from a few enthu­
siastic users). The proliferating literature and evidence-based guidelines will
be of assistance in designing projects while accommodating the increasingly
diverse and growing community of users.

Researcher’s Agenda

The criteria for success in research favor innovations that work for broad com­
munities of users performing useful tasks over longer time periods. At the same
time, researchers are struggling to understand what kinds of imaginative con­
sum er products will attract, engage, and satisfy diverse populations. The oppor­
tun ities for researchers are unlimited. There are so many interesting, important,
and doable projects that it may be hard to choose a direction. The goal of

Researcher’s Agenda 45

universal usability through plasticity of interface designs will keep researchers
busy for years. Getting past vague promises and measuring user performance
with alternate interfaces will be central to rapid progress. Each study has two
parents: the practical problems facing designers and the fundamental theories
based on principles of human behavior and interface design. Begin by propos­
ing a lucid, testable hypothesis. Then consider the appropriate research meth­
odology, conduct the study, collect the data, and analyze the results. Each study
also has three children: specific recommendations for the practical problem,
refinements of theories, and guidance for future researchers.

WORLD WIDE WEB RESOURCES

www. pearsonglobaleditions.com / shneiderman

This book is accompanied by a website (www.pearsonglobaleditions.com/
shneiderman) that includes pointers to additional resources tied to the contents

of each chapter. In addition, this website contains information for instructors, stu­
dents, practitioners, and researchers. The links for Chapter 1 include pointers to

general resources on human-computer interaction, such as professional societies,
government agencies, companies, bibliographies, and guidelines documents.

Readers seeking references to scientific journals and conferences can

consul t the online searchable bib liography for human-computer interaction
(http://www.hcibib.org/). Maintained since 1989, unde r the heroic leadership
of Gary Perlman, the HCI Bibliography makes available more than 120,000
journal, conference, and book abstracts plus link col lections on many top­

ics, including consulting companies, education, history, and international
deve lopment.

Some wonderful World Wide Web resources are:

• Resource on usability methods and guide lines from the U.S.
government: http://www.usability.gov/

• IBM’s extensive guide to user -centered design methods:
http://www. i bm .com/des ign/

• Interaction Design Foundation’s free online educational materials:
https://www.interaction-design.org/

• Diamond Bullet Design:
http://www.usabilityfirst.com/

E-mai l lists for announcements and discussion lists are maintained by

ACM SIGCHI (http://www.acm.org/sigchi/) and by the British HCI Group (http://
www.bcs-hci.org.uk/), which also sponsors the frequently updated Usability

News (http://usabil itynews .bcs.o rg/) .

46 Chapter 1 Usability of Int eractive Systems

Discussion Questions

1. Devise an outline, consistent with the scientific method, which interface
researchers should follow to validate their designs.

2. List some characteristics of successful user-interface designers with respect
to the ir approach to solving UI problems.

3. As noted in this chapter, some skeptics feel that accommodating diversity
requires dumbing-down or lowest-common-denominator strategies. However,
the au thors claim that in their experience, rethinking interface designs to
accommodate these di, rersity situations will result in a better product for all
users. Give an example of a product that meets the specific needs of a certain
group of people, yet gives all user s a better experience.

4. How can designers enco urage novice u sers to use a system?

5. Suggest three usability measures that can be direct ly used to produce a
practical eval uatio11 of a sys tem . Keep the goals of efficiency and satisfactio11
in mind with these measures.

References

Specialized reference s for this chapter appear here; general information resour ces are
listed in the following section.

Bias, Randolph and Mayh ew, Deborah (Editors), Cost-Justifi;ing Usability: An Update for
the Internet Age, 2nd Edition, Morgan Kaufmann, San Francisco, CA (2005).

Center for Information Technolo gy Accommodation, Section 508: The road to accessibi l­
ity, Genera l Services Admi11is tration, Wa shin gton, DC (2015). Availab le at http:/ /
www .section508.gov.

Friedman, C., Rubin, J., Brown, J., Buntin, M., Corn, M., Etheredge, L., Gunter , C.,
Musen, M., Platt, R., Stead, W., Sullivan, K., and Van Houweling, D., Toward a sci­
ence of learning sys tem s: A research agenda for the high -functioning learning health
sys tem, Journal of the American Medical Informatics Association (2014), 1-6.

Froehlich, Jon, Findlater, Leah , and Landay , James, The d esign of eco-feedback technol­
ogy, Proceedings CHI 2010 Conference: on Human Factors in Con1puting Systems, ACM
Press, New York (2010), 1999- 2008.

Jones, Doug las W., and Simons, Barbara, Broken Ballots: Will Your Vote Count? Center for
the Study of Language and Information (2012).

Norooz, L., Mauriello, M., McNally, B., Jorgenson, A., and Froehlich, J., BodyVis: A new
approach to body learning through wearable sensing and visualization , Proceed-
ings CHI 2015 Conference: Human Factors in Cornputing Systen1s, ACM Press, New York
(2015), 1025-1034.

References 47

Summers, K., Chisnell, D., Davies, D., Alton, N ., and McKeever, M., Making voting acces­
sib le: Designing digital ballot marking for peopl e with low literacy and mild cognitive
disabilities. USENIX Journal of Election Technology and Systen1s (JETS) 2, 2 (2014).

Tu l lis, Thoma s, and Albert, William, Measuring the User Experience: Collecting, Analyzing,
and Presenting Usability Metrics, 2nd Edition, Morgan Kaufmann (2013).

Whitworth, Brian and De Moor, Aldo (Editors), Handbook of Research on Socio-Technical
Design and Social Networking Systen1s, IGI Global, Hers h ey, P A(2009).

General information resources
Primary journals include the followin g:

ACM interactions: A Magazine for User interface Designers, ACM Press

ACM Transactions on Accessible Co111puting, ACM Press

ACM Transactions on Computer-Hu111an Interaction (TOCHI), ACM Press

AIS Transactions on Human-Co1nputer Interaction, AIS

Behaviour & Infonnation Technology (BIT), Taylor & Francis Ltd.

Con1puter Supported Cooperative Work, Springer

Hurnan-Con1puter Interaction, Taylor & Francis Ltd.

lnforn·1ation Visualization, Sage

Interacting with Co1nputers, Oxford Un iversity Press

International Journal of Hun1an-Computer Interaction, Taylor & Francis Ltd.

International Journal of Hun1an-Con1puter Studies, Elsevier

Journal of Usability Studies, User Experience Prof ess ional s Association

Universal Access in the Information Society, Spr in ge r

Other journal s that regularly carry articles of interest includ e:

ACM: Con·1munications of the ACM (CACM)

ACM Transactions on Graphics

ACM Transactions on Inforrnation Syste,ns

ACM Transactions on Interactive Intelligent Systen1s

ACM Transactions on the Web

Cognitive Science

Con1puters in Hun1an Behavior

Ergono1nics

Human Factors

IEEE Co,nputer

IEEE Con1puter Graphics and Applications

IEEE Transactions on Human-Machine Systems

IEEE Transactions on Visualization and Computer Graphics

Journal of Con1puter-Mediated Com111unication

Journal of Visual Languages and Cornputing

48 Chapter 1 Usability of Interactive Systems

Personal and Ubiquitous Cornputing

Presence

Psychnology

Technical Connnunication

User lvlodeling and User-Adapted Interaction

Virtual Reality

The Association for Computing Machinery (ACM) has a Special Interest Group on Com­
puter-Human Interaction (SIGCHI), which holds regularly scheduled conferences. ACM
also publishes the highl y regarded Transactions on Hu1nan-Con1puter Interaction and the
lively magazine interactions. Other ACM Special Interest Groups, such as Graphics and
Interactive Techniques (SIGGRAPH), Accessible Computing (SIGACCESS), Multimedia
(SIGMM), and Hypertext and the Web (SIGWEB), also produce conferences and nevvslet­
ters. Other relevant ACM groups are Computers and Society (SIGCAS), Design of Con,­
munication (SIGDOC), Groupware (SIGGROUP), Information Retrieval (SIGIR), and
Mobility of Systems, Users, Data, and Computing (SIGMOBILE).

The IEEE Computer Society, through its many conferences, transactions, and maga­
zines, covers user-interface issues. Similarly, the business-oriented Association for Infor­
mation Systems (AIS) ha s a SIGHCI that publishes a journal and runs sessions at severa l
conferences. The long-established Human Factors & Ergonomics Society also runs annual
conferences and has a Computer Systems Technical Group with a ne,,v-sletter. Addition ­
ally, the Society for Technical Communications (STC), the American Institute of Graphic
Arts (ATGA), the International Ergonom ics Association, and the Ergonomics Society
iricreasingly focus on user interfaces . The influential business-oriented User Experience
Professionals Association (UXP A) publishes the UX- User Experience magazine and the
online Journal of Usability Studies. The UXPA also spawned the annual World Usability
Day with hundreds of events around the world each Novembe r.

The International Federation for Information Processing has a Technical Commit­
tee (TC.13) and Working Groups on Human-Computer Interaction. The British Com­
puter Society Human -Computer Interaction Group has held an international conference
since 1985. The French Association Francophone pour !’Interaction Homme -Machine
(AFIHM), the Spanish Asociaci6n lnteracci6n Persona-Ordenador (AIPO), and othe r
associations promote HCI within their language communities. Other groups conduct
important events in South Africa, Australia/New Zealand, Scandinavia, Asia, Latin
America, and elsewhere.

Conferences – such as the ones held by the ACM (especially SIGCHI), IEEE, Human
Factors & Ergonomics Society, and IFIP-often have relevan t papers presented and pub­
lished in the proceedings . INTERACT, Human-Computer Interaction Internationa l, and
Work with Computing Systems are conference series that cover user -interface issues
broad ly. Many specia lized conferences may also be of interest: for examp le, User Inter ­
faces Software and Technology, Hypertext, Computer-Supported Cooperative Work,
Intelligent User Interfaces, Computers and Accessibility, Ubiquitous Computing, Co1n­
puters and Cognition, Designing Interactive Systems, and more.

Brad Myers ‘s brief history of HCI (ACM Interactions, March 1998) is one starting point
for those who want to study the emergence and evolution of this field. James Martin
provided a thoughtful and useful survey of interactive systems in his 1973 book Design
of Man-Camputer Dialogues. Ben Shneiderman’s 1980 book Soft,vare PsychologtJ: Hun·1an
Factors in Computer and Inforn1ation Systeins promoted the use of controlled experimenta l

References 49

teclmiques and scientific research methods. Rubinstein and Hersh’s The Hun1an Factor:
Designing Co,nputer Syste,ns for People (1984) offered an appealing introduction to com­
puter-system design and many useful guidelines. The first edition of this book, pub ­
lished in 1987, reviewed critical issues, offered guidelines for designers, and suggested
research directions .

A steady flov.1 of influential books has stimulated widespread media and public atten ­
tion about usability issues, including Nielsen’s Usability Engineering (1993), Landauer’s
The Trouble with Computers (1995), and Nielsen’s Designing Web Usability (1999). Don
Nor1nan’s 1988 book The Psychology of Everyday Things (reprinted and revised in 2013 as
The Design of Everyday Things) is a refreshing look at the psychological issues involved in
the design of the everyday technology that surrounds us.

As the field matured, subgroups and publications centered around specia lized top­
ics emerged; this happened with mobile computing, web design, online communities,
information visualization, virh1al environments, and so on. The following list of g1tide­
lines doc1tments and books is a startin g point to an exploration of the large and growing
literature.

Guidelines documents
Apple Computer, Inc., Hu,nan Interface Guidelines, Version for the Mac OS X, iPhone, iPad,

and Apple Watch, Apple, Cupertino, CA (April 2015). Available at http:// developer.
apple.co m /.

-Exp lains how to design consistent visual and behavioral properties for Apple
products.

International Organization for Standardization, ISO 9241 Ergonomics of Human-System
Interaction, Geneva, Sv.1itzerland (updated 2013). Availab le at http://www.iso.org/ .

-Thorough genera l introduction, covering dialog principles, guidance on usabil­
ity, presentation of information, user guidance, menu dialogs, command dialogs,
direct-manipulation dialogs, form -filling dialogs, and much more. This is an
important source for many countries and companies.

Microsoft, Inc., The Microsoft Windoivs User Experience Interaction Guidelines, Redmond,
WA (2015). Available at https:/ / msdn.microsoft.com/.

– Describes design principles, controls, text, interaction, windovvs, and aesthetics.

United Kingdom Health & Social Care Information Centre, User Interface Guidance Oune
2015). Available at http:/ /sys terns.hscic.gov .uk/ data/ cui/uig.

– Detailed guidelines oriented to medical systems.

United Kingdom Ministry of Defence, Hurnan Factors for Designers of Systen1s, De­
fence Standard 00-250 Oune 2013). Available at http:/ /vvww.dstan.mod.uk/
data /00/250 /00000100 .

– Describes human factors, integration processes, requirements, and acceptance
testing.

U.S. Dept. of Defense, Hun1an Engineering Design Criteria Standard, Military Standard
MIL-STD-1472G, U.S. Government Printing Office, Washington, DC (2012).

-Covers traditional ergonomic and anthropometric issues. Later editions pay in­
creasing attention to user-computer interfaces. Interesting and thought-provoking
reminder of many human-factors issues .

50 Chapter 1 Usab ility of Interactive Syste ms

U.S. Federal Aviation Administration, The Hun1an Factors Design Standard, Atlantic City,
NJ (updated May 2012). Available at http://hf.tc.faa.gov/hfds/.

– Extensive compilation of human -factors standards for contractors to follow, espe ­
cially relevan t to aircraft and air-traffic control.

U.S. National Cancer Institute, Research-based Web Design and Usability Guidelines, Dept.
of Health & Human Services, Nationa l Institutes of Health (2006, updated on the
web 2015). Available at http://guidelines.usabi lity.gov/.

– Author ita tive and packed with numerous full-color examples of informat ion­
oriented websites.

World Wide Web Consortium’s Web Accessibility Initiative, Web Content Accessibility
Guidelines 2.0 (2008). Availab le at http://wv,;w.w3.org/WAI/.

-Practical, implementab le three-level pr ioritization of \,veb design gu ide lines for
users with disabilities. The Web Accessibility Initiative (WAI) develops strategies,
guidelines, and resources to help make the web accessible to people with dis­
abilities. Four principles are offered: Perceivable, Operable, Understandable, and
Robust.

World Wide Web Consor tium, Web Accessibiliti; Evaluation Tools (2014). Available at
http:/ /,vww.w3.org/WAI/ER/tools/.

– An occasionally updated list of software tools re lated to accessibility; demonstrates
lively activity.

Books
Allen, J., and Chudley, J., Snzashing UX Design: Foundations for Designing Online User

Experiences, Wiley, Chichester (2012).

Anderson, S., Seductive Interaction Design: Creating Plat;ful, Fun, and Effective User
Experiences, New Riders (2011).

Barnum, Carol M., Usability Testing Essentials: Ready, Set … Test! Morgan
Kaufmann (2011).

Baxter, Kathy, and Courage, Cathe rine, Understanding Your Users: A Practical
Guide to User Requirements Methods, Tools, and Techniques, 2nd Edit ion, Morgan
Kaufmann (2015).

Bell, Genevieve, and Dourish, Pau l, Divining a Digital Future: Mess and MythologtJ in
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boyd, danah, It’s Con1plicated: The Social Lives of Netlvorked Teens, Yale University
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Buley, Leah, The User Experience Tean1 of One: A Research and Design Survival Guide,
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Refe rences 51

Calvo, Rafael A., and Peters, Dorian, Positive Conzputing: Technology for Wellbeing and
Hunian Potential, MIT Press (2014).

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Chapman, C., The Srnashing Idea Book: Frorn Inspiration to Application, Wiley (2011).

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Morgan Kaufmann (2012).

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Harris, D., Writing Hurnan Factors Research Papers: A Guidebook. Ashgate Publishing
(2012).

Hartson, R., and Pyla, P., The UX Book: Process and Guidelines for Ensuring a Quality User
Experience, Morgan Kaufmann (2012).

Hearst, Marti A., Search User Interfaces, Cambridge University Press, New York,
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52 Chapter 1 Usabi lity of Int eractive Systems

Katz, J., Designing Infor1nation: Hu1nan Factors and Corrnnon Sense in Inforn1ation Design.
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References 53

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54 Chapter 1 Usability of Interactive Systems

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Amsterdam (2014).

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Videos
Video is an effective medium for presenting the dynamic, graphical, and interactive
nature of modern user interfaces. A wonderhtl set of lech1res from Stanford University’s
CS547 Human-Computer Interaction Seminar can be found at http :/ /hci.s tanford.edu/
courses/ cs547 /.

Inspirational videos from the annual Technology, Entertainment & Design (TED) Con­
ference, which covers a wide range of topics including visionary user -interface themes,
are found at http://w,.vw.ted.com/index.php/talks/. Another exceptional resource is
YouTube (http:/ /www .youtube.com/), v,rhere a search on “user interfaces” produces a
list of hundred s of recent product demonstrations, research reports, and some clever and
funny technology demonstrations.

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CHAPTER

Usal1ilib>j

99 Social scientists have shown that teams and organizations whose
members are heterogeneous in meaningfu l ways, for examp le, in

skill set, education, work experiences, perspectives on a problem,
cultura l orientation, and so forth, have a higher potential for ”

innovation than teams whose members are homogeneous.

Beryl Nelson

Communications of the ACM, November 2014

99 I feel … an ardent desire to see knowledge so disseminated through

the mass of mankind that it may, at length, reach even the ”
extremes of society: beggars and kings.

Thomas Jefferson

Reply to Ame rican Philosophical Society, 1808

CHAPTER OUTLINE
2.1 Introduction

2.2 Variations in Physical Abilities
and Physical Workplaces

2.3 Diverse Cognitive and Perceptual
Abilities

2.4 Personality Differences

2.5
2.6
2.7
2.8
2.9

Cultural and International Diversity

Users with Disabilities

Older Adult Users

Children

Accommodating Hardware and
Software Diversity

57

58 Chapter 2 Universal Usability

2.1 Introduction

The remarkable div ers ity of hum an abil ities, background s, motivat ions , per­
sonalities, cultur es, and work styles challeng es int erface design ers. A youn g
female designer in India ,..,ith computer training and a desire for rapid interac ­
tion using densel y packed displa ys may have a hard time designing a success ­
ful interf ace for older male arti sts in France with a more leisurely and free-form
work style. Und ers tanding the phy sical, int ellectual , and personal ity differ­
ences among users is vital for expanding market share, supporting required
government services, and enabling crea tive participa tion by the broades t
possible set of users. As a profe ssion, we will be remembered for how well we
meet our users’ need s. That’ s the ultimate goal: addre ssing the needs of all
users (Fig. 2.1).

Raising the F1oor
OH£.QZE -FIT8.0 NE DfQITAL IHa.US ION

wtio ‘” .,. Wlltt – do RHOUrtel Get lnvotwd News. PrttS cont.Kt us

‘- -I

LATEST NEWS RtF people, Join us!

Tl’tl nslale to. .. 1:1 TEXT AND DISPLAY O RESET ALL

[B LAYOUT AND NAVl Tl N

l.’I LINKS AND BIITTONS

□ EMPHAS IZE LINKS
Makes links larger, bold, and
undertined

□ MAKE INPUTS LARGER
Makes buttons, drop-down menus,
texl-fiekls, and other inputs larger

Raising the Floor is an organization of diverse people from industry. academia, NGOs and other sectors who have c.ome together to
ensure that people who face barriers due to disability, literacy, digital-literacy, and aging are able to fully understand, access, and
use the digital world we are creating (the web, computers, tablets, phones, educational materials, ticket machines, thermostats, and
even home appliances). Our central focus is the development of the Global Public Inclusive Infrastructure (GPII).

Benefits of RtF for …………

users service providers employers

FIGURE 2. 1
The website of Raising the Floor includes universa l accessibi lity features suc h
as options fo r emphasizing the lin ks or making buttons large r, offering severa l
font sizes, contrast , tex t desc riptio ns of photos, t ranslatio n services , and so on
(http ://ww w . ra isi ngthef l oo r. net) .

2.2 Variations in Physical Abi lities and Physical Workplaces 59

The huge international consumer market in mobile de,,ices has raised the
pressure for designs that are universally usable. While skeptics suggest that
accommodating diversity requires dumbing-down or lowest-common­
denominator strategies, our experience is that rethinking interface designs for
differing situations often resul ts in a better product for all users. Measures to
accommodate the special needs of one group, such as curb cuts in sidewalks
for wheelchair users, often have payoffs for many groups, such as parents
with baby stroller s, skateboard riders, travelers with wheeled luggage, and
delivery people with handcarts. With this in mind, this chapter introduces the
challenges posed by physical, cognitive, perceptual, personality, and cultural
differences. It covers considerations for users with disabilities, older adults,
and young users, ending wi th a discussion of hardware and sof tware diver­
sity . The important issues of differerlt usage profiles (novice, intermittent, and
expert), wide-ranging task profiles, and multiple interaction styles are covered
in Chapter 3.

2.2 Variations in Physical Abilities and Physical
Workplaces

Accommodating diverse human perceptual, cognitive, and motor abilities is a
challenge to every designer. Fortunately, ergonomics researchers and practitio­
ners have gained substan tial experience from design projects with automobiles,
aircraft, cellphones, and so on. This experience earl be applied to the design of
user interfaces and mobile devices.

Basic data about human dimensions comes from research in anthropometry
(Preedy, 2012). Thousands of measures of hundreds of features of peopl e- male
and female, young and adult, European and Asian, underweight and over­
weight, tall and short – provide data to construct 5- to 95-percentile design
ranges. Head, mouth, nose, neck, shoulder, chest, arm, hand, finger, leg, and
foot sizes have been carefully catalog ed for a va riety of populations. The great
diversity in these static measures reminds us that there can be no image of an
“average” user and that compromises must be made or multiple versions of a
system must be constructed.

Cellphone keypad design parameters – placement, size, distance between
keys, and so forth (Section 10.2)-e vo lved to accommodate differences in users’
physical abilities. People with especially large or smal l hands may have diffi­
culty using standard cellphones or keyboards, but a substantial fraction of the
population is well served by one design. On the other hand, since screen­
brightness preferences vary substan tially , designers often enab le users to con­
trol this parameter. Similarly, controls for chair seat and back heights and for

60 Chapter 2 Universal Usability

disp lay angles allow individual adjustment. When a single design cannot
accommodate a large fraction of the population, multiple versions or adjust­
ment controls are helpful.

Physical measures of static human dimensions are not enough. Measures of
dynamic actions-such as reach distance while seated, speed of finger presses,
or strength of lifting-are also necessary.

Since so much of work is related to perception, designers need to be aware of
the ranges of human perceptual abilities, especially with regard to vision (Ware,
2012). For example, researchers consider human response time to varying visual
stimuli or time to adapt to low or bright light. They examine human capacity to
identify an object in context or to determine the velocity or direction of a moving
point. The visual system responds differently to various colors, and some peo­
ple have color deficiencies, either permanently or temporarily (due to illness or
medication). People’s spectral range and sensitivity vary, and peripheral vision
is quite different from the perception of images in the fovea (the central part of
the retina). Designers need to study flicker, contrast, motion sensitivity, and
depth perception as well as the impact of glare and visual fatigue. Finally,
designers must consider the needs of people who wear corrective lenses, have
visual impairments, or are blind.

Other senses are also important: for example, touch for keyboard or touch­
screen entry and hearing for audible cues, tones, and speech input or output
(Chapter 10). Pain, temperature sensitivity, taste, and sme ll are rare ly used for
input or output in interactive systems, but there is room for imaginative
applications.

These physical abilities influence elements of the interactive-system design.
They also play a prominent role in the design of the workplace or workstation
(or p laystation). The Hurnan Factors Engineering of Con1puter Workstations stan ­
dard (HFES, 2007) lists these concerns:

• Worktable and display-support height

• Clearance under work surface for legs

• Work-surface width and depth

• Adjustabi]jty of heights and angles for chairs and work surfaces

• Posture-seating depth and angle, backrest height, and lumbar support

• Availability of armrests, footrests, and palmrests

• Use of chair casters

Workplace design is important in ensuring high job satisfaction, good
performance, and low error rates. Incorrect table heights, uncomfortable
chairs, or inadequate space to place documents can substantially impede
work. The standards document also addresses such issues as illumination
levels (200 to 500 lux); glare reductio11 (antiglare coatings, baffles, mesl1,

2.3 Diverse Cognitive and Perceptual Abilities 61

positioning); luminance balance and flicker; equipment reflectivity; acoustic
noise and vibration; air temperature, movement, and humidity; and equipment
temperature.

The most elegant screen design can be compromised by a noisy environ­
ment, poor lighting, or a stuffy room, and that compromise will eventually
lower performance, raise error rates, and discourage even motivated users.
Thoughtful designs, such as workstations that provide wheelchair access and
good lighting, will be even more appreciated by users with disabilities and
older adults.

Another physical-environment consideration involves room layout and the
sociology of human interaction. With multiple workstations in a classroom or
office, differer1t layouts can er1courage or limit social interaction, cooperative
work, and assistar,ce with problems. Because users can often quickly help one
another with minor problems, there may be an advantage to layouts that
group several terminals close together or that enable supervisors or teachers to
view all screens at once from behind. On the other hand, programmers, reser­
vations clerks, or artists may appreciate the quiet and privacy of their own
workspaces.

Mobile devices are increasingly being used while walking or driving and
in public spaces, such as restaurants or trains where lighting, noise,
movement, and vibration are part of the user experience. Designing for these
more fluid environments presents opportunities for design researchers and
entrepreneurs.

2.3 Diverse Cognitive and Perceptual Abilities

A vital foundation for interactive-system designers is an understanding of the
cognitive and perceptual abilities of the users (Radvansky and Ashcraft, 2013).
The journal Ergonomics Abstracts offers this classification of human cognitive
processes:

• Short-term and working memory

• Long-term and semantic memory

• Problem solving and reasoning

• Decision making and risk assessment

• Language communication and comprehension

• Search, imagery, and sensory memory

• Learning, skill development, knowledge acquisition, and concept attainment

62 Chapter 2 Universal Usability

It also suggests this set of factors affecting percep tual and motor performance:

• Arousal and vigilance

• Fatigue and sleep deprivation

• Perceptual (mental) load

• Knowledge of results and feedback

• Monotony and boredom

• Sensory deprivation

• Nutrition and diet

• Fear, anxiety, mood, and emotion

• Drugs, smoking, and alcohol

• Physiological rhythms

These vital issues are not discussed in depth in this book, but they have a pro­
found influence on the design of user interfaces. The term intelligence is not
included in this list because its nature is controversial and measuring different
forms of intelligence is difficult.

In any application, background experience and knowledge in the task and
interface domains play key roles in learning and performance. Task- or computer­
skill inventories can be helpful in predicting performance.

2.4 Personality Differences

Some people are eager to use computers and mobile devices, while others find
them frustrating. Even people who enjoy using these techno logies may have very
different preferences for interaction styles, pace of interaction, graphics versus
tabular presentations, dense versus sparse data presentation, and so on. A clear
understanding of personality and cognitive styles can be helpful in designing
interfaces for diverse communities of users.

One evident djfference is between men and women, but no clear pattern of
gender -related preferences in interfaces has been documented. While the major­
ity of video -game players and designers are young males, some games (such as
The Si1nsTM, Candy Crush Saga, and Farmville) draw ample numbers of female
players. Designers can get into lively debates about why many women prefer
certain games, often speculating that women prefer less violent action and
quieter soundtracks. Other conjectures are that women prefer socia l games,
characters with appealing personalities, softer color patterns, and a sense of
closure and completeness. Can these informal conjectures be converted to
measurable criteria and then validated?

2.5 Cultural and Internationa l Diversity 63

Turning from games to productivity tools, there is also a range of reactions to
violent terms such as KILL a process or ABORT a program. These and other
potentially unfortunate mismatches between the user interface and the users
might be avoided by more thoughtful attention to individual differences among
users.

Unfortunately, there is no siJnple taxonomy of user personality types. A
popular, but controversial, technique is the Big Five Test, based on the OCEAN
model (Wiggins, 1996): Openness to Experie11ce/lntellect (closed/ ope11), Consci­
entiousness (disorganized/organized), Extra version (introverted/ extraverted),
Agreeableness (disagreeable/agreeable), and Neuroticism (calm/nervous).
There are hundreds of other psychological scales, including risk taking versus
risk avoidance; internal versus external locus of control; reflective versus
unpulsive behavior; convergent versus divergent thinking; high versus low
anxiety; tolerance for stress; tolerance for ambiguity, motivation, or compul ­
siveness; field dependence versus independence; assertive versus passive per­
sonality; and left- versus right-brain orientation. As designers explore comp ut er
applications for the home, education, art, music, and enter tainm ent, they may
benefit from paying greater attention to personality types. Consumer-oriented
researchers are especially aware of the personality distinctions across market
segments, so as to tune their advertising for niche products designed for tech­
savvy youngsters versus family-oriented parents.

Another approach to personality assessment is by studying user behavior.
For example, some users file thousands of e-mails in a well -organized hierarchy
of folders, while others keep them all in the inbox, using search strategies to find
what they want later. These distinct approaches may well relate to personality
var iables, giving designers the clear message that multiple requirements must
be satisfied by their designs.

2.5 Cultural and International Diversity

Another perspective on individual differences has to do with cultural, ethnic,
racial, or linguistic background (Quesenbery and Szuc, 2011; Marcus and Gould,
2012; Salgado, 2012). Users who were raised learning to read Japanese or Chi­
nese will scan a screen differently from users who were raised learning to read
English or French. Users from reflective or traditional cultures may prefer inter­
faces with stable displays from which they select a single item, while users from
action-orien ted or novelty-based cultures may prefer animated screens and
multiple clicks. Preferred content of webpages also varies; for example, univer­
sity home pages in some cultures emphasize their impressive buildings and
respected professors lecturing to students, while others highlight student team

64 Chapter 2 Universal Usability

projects and a lively social life. Mobile device preferences also vary across cul­
tures that lead to rapidly changing styles in successful apps, which may include
playful designs, music, and game-like features.

More arld n1ore is being learned about computer users from different cultures,
but user experience designers are still struggling to establish guidelines that are
appropriate across multiple languages and cultu res (Sun, 2012; Pereira and
Baranauskas, 2015). The growth of a worldwide computer and mobile device
market means that designers must prepare for internationalization. Software
architectures that facilitate customization of local versions of user interfaces
offer a competitive advantage (Reinecke and Bernstein, 2013). For example, if all
text (instructions, help, error messages, labels, and so on) is stored iI1 files,
versions in other languages can be generated with little or no additional
programming. Hardware issues include character sets, keyboards, and special
input devices. User-interface design concerns for internationalization include
the following:

• Characters, numerals, special characters, and diacriticals

• Left-to-right versus right-to-left versus vertical input and reading

• Date and time formats

• Numeric and currency formats

• Weights and measures

• Telephone numbers and addresses

• Names and titles (Mr., Ms., Mme., M., Dr.)

• Social Security, national identification, and passport numbers

• Capitalization and punctuation

• Sorting sequences

• Icons, buttons, and colors

• Pluralization, grammar, and spelling

• Etiquette, policies, tone, formality, and metaphors

The list is long and yet incomplete. Recent studies of consumer use show perfor ­
mance and preference differences for information density, animation, cute char­
acters, eagerness for timely updates, incentives for social participation, and
game-like features. Whereas early designers were often excused from cultural
and linguistic slips, the current highly competitive atmosphere means that more
effective localization may produce a strong advantage. To develop effective
designs, companies run usability studies with users from different coU11tries,
cultures, and language communities.

The role of information technology in intematio11al development is steadily
growing, but much needs to be done to accommodate the diverse needs of users

2.5 Cultural and Inte rnationa l Diversity 65

wi th vas tly different language skills and technology access. To promote interna­
tional efforts to foster successful implementation of information technologies,
representatives from around the world meet regularly for the United Nations
World Summit ort the Information Society. They declared their

desire and commitm ent to build a people -centered, inclusive and deve lopmen t­
or iented Information Society, where everyone can create, access, utilize and
share information and knowledge, enabling individuals, communities and
peoples to achieve their full potential in promoting their sustainable develop­
ment and improving their quality of life, premised on the purposes and prin­
ciples of the Charter of the United Nations and respecting fully and upholding
the Unive rsal Declaration of Human Rights.

The plan calls for applications to be “accessible to all, affordable, adapted to
local needs in languages and culture, and [to] support sustainable develop­
ment.” The UN Sustainability Development Goals include erad icate extreme
poverty and hunger; reduce child mortality; combat HIV/AIDS, malaria, and
other diseases; and ensure environmental sustainab ility. Information and com­
mU11ications technologies can play important roles in developing the infrastruc ­
ture that is needed to achieve these goals (Fig. 2.2).

FIGURE 2.2
Designing for cellphones can open the door to a wider audien ce (Medh i et al., 2011 ),
for example, in developing countries where feature phones often are the only way to
access the internet, literacy may be an issue, and users have very low monthly limits
on the data volume they can use.

66 Chapter 2 Universal Usability

2.6 Users with Disabilities

When digital content and services can be flexibly presented in different formats,
all users benefit (Horton and Quesenbery, 2014). However, flexibility is most
appreciated by users witl, disabilities who now can access content and services
using diverse input and output devices. Blind users may utilize screen readers
(speech output such as JAWS or Apple’s VoiceOver) or refreshable braille dis­
plays, while low-vision users may use magnification. Users with hearing impair­
ments may need captioning on videos and trru,scripts of audio, and people witl,
limited dexterity or other motor impairments may utilize speech recognition,
eye-tracking, or alternative keyboards or pointing devices (Fig. 2.3). Increas­
ingly, especially on Apple products, iliese alternate forms of input or output are
integrated into technology out of the box (other laptops, tablets, ru,d smart­
phones have add-on screen reader and magnification capability, and a small
number of laptops have built -in eye tracking).

There is a long history of research on how users with perceptua l or motor
impairments (such as iliose described above) interact with technology, and
research on intellectual or cognitive impairments is now also increasing (Blanck,
2014; Chourasia et al., 2014). In some cases, people wiili intellectual impairments

FIGURE 2.3

A young man uses a wheelc hair-moun ted augmentative communication and contro l
device to control a standard television. New universal remo te console standards can
allow people to use communication aids and other personal electronics as alternate
interfaces for digital electronics in their environments (http://trace.wisc.edu ).

2.6 Users with Disabilities 67

need transformation of content, but in other cases, no modifications or assistive
technologies are needed. Designing for accessibility helps everyone. The same
captioning on video that is utilized by users with hearing impairments is also
used by users watching video in noisy locations, such as gyms, bars, and airpor ts.
Many accessibility features help with graceful presentation of content in multiple
formats, allowing for flexibility in presentation on small screens of mobile devices
or with audio output instead of visual output. As users are increasingly on the go
and experience “situational impairments,” these accessibility features help all
users, who may be in situations where they canno t see their screen (e.g., they are
driving a car) or cannot play audio out loud (e.g., on a plane).

For interfaces to be accessible for people with disabilities, they generally need
to follow a set of design guidelines for accessibility. The ir,ternational standard s
for accessibility come from the Web Accessibility Initiative, a project of the
World Wide Web Consortium. The best-known standards are the Web Content
Accessibility Guidelines (WCAG); the current version is WCAG 2.0 (since 2008,
http:/ /www .w3.org /TR/WCAG20/). There are also other guidelines such as
the Authoring Tool Accessibility Guidelines (ATAG) for developer tools and the
User Agent Accessibility Guidelines (UAAG) for browsers. Other guidelines,
such as EPUB3, exist for ebooks. Because WCAG 2.0 is the best -known, best­
understood, and most-documented set of accessibility guidelines in the wor ld,
there is a companion guide, known as Guidance on Applying WCAG 2.0 to
Non-Web Information and Communications Technologies (WCAG21CT), for
utilizing WCAG concepts in non -vveb technologies (Cunningham, 2012).

These concepts of digital accessibility are not new. The first version of WCAG
came out in 1999, and cap tioning of video has existed for more than 30 years.
The accessibi lity features are not technica lly hard to accomp lish. WCAG
requires, for instance, that all graphics have ALT text describing the image, that
a webpage not have flashing that could trigger seizures, that tables and forms be
marked up with appropriate labels (such as first name, last name, street address
instead of FIELDl, FIELD2, FIELD3) to allow for identification. Another WCAG
requirement is that all content on a page can be accessed even if you cannot use
a pointing device through keyboard access. Creating accessible digital content
is simply good coding, and it doesn’t change, in any way, how informatio n is
visual ly presented.

Similar concepts apply for creating accessible word-processing documents,
presentations, and PDF files-appropriate labeling and descriptions ensure that
a document or presentation will be accessible . Multiple approaches for accom­
plishing a task allow for successfu l task completion for a diverse population of
users. Even when properly utilizing guidelines such as WCAG 2.0, it is a good
idea to evaluate for success by usability testing with people with disabilities,
expert reviews, and automated accessibility testing.

The Web Content Accessibility Guidelines form the basis for many of the
laws and regulations around the world. Section 508 of the Rehabilitation Act in

68 Chapter 2 Universal Usability

the United States requires that when the federal government develops, pro­
cures, maintains, or uses electronic and information technology, that technology
must be accessible for employees and members of the general public who have
disabilities. This applies to procurement of both l-1ardware and software technol­
ogy as well as ensuring that websites are accessible (Lazar and Hochheiser, 2013;
Lazar et al., 2015).

The Americans with Disabilities Act, as interpreted by federal courts and the
U.S. Department of Justice, also reqt1ires accessibility of state and local govern­
ment websites as well as those of private companies and organizations that are
considered “public accommodations” (stores, museums, hotels, video rental,
etc.). The U.S. Department of Justice is also enforcing accessibility of websites
and instructional materials at universities. Lawsuits such as those against Tar­
get, Netflix, Harvard University, and MIT highlight the increasing importance
and expectations of digital accessibility.

The European Union Mandate 376 (http:/ /www.mandate376.eu/) will
reqt1ire procurement and de, relopment of accessible technologies by EU gov­
ernments and will coordinate with U .S. Section 508, utilizing WCAG 2.0 and
enabling developers to easily satisfy both U.S. and EU legal requirements.
Prior to EU Mandate 376, many European countries, such as the UK, Italy, and
Germany, and other countries around the world, including Australia and
Canada, also had information technology accessibility requirements. The cov­
erage (only government technology or also public accommodations), required
reporting requirements, and penalties for noncompliance differ from country
to country.

The United Nations Convention on the Rights of Persons with Disabilities
(CRPD, http:/ /wvvw .un.org / disabilities/ convention/ conventionfull.shtml), an
international human rights agreement, also addresses accessible technology.
Article 9 of the CRPD calls upon countries to “Promote access for persons with
disabilities to new information and communications technologies and systems,
including the Internet,” and article 21 encourages countries to “[provide] infor­
mation intended for the general public to persons with disabilities in accessible
formats and technologies appropriate to different kinds of disabilities.”

Accessibility is a core feature of contemporary information systems, baked
into development from the start. Programmers who follow coding standards
and guidance from WCAG 2.0 add minimal cost in development ye t provide
valuable services to all users. By contrast, implementers wl10 seek to retrofit for
accessibility find that their effort is much greater (Wentz et al., 2011).

Increasingly, a person’s economic success depends on equal access to digi­
tal content and services. University classes take place online, job postings are
made online, and job applications must be submitted online. Prices are often
lo\,ver when using a company website instead of calling the company on the
phone. When people wi th disabilities l,ave equal access to digital conten t and
services, they have access to the full ra11ge of economic opportunities. The

2 .7 Older Adu lt Users 69

good news is that computer scientists, software engineers, developers, design­
ers, and user experience professionals have the opportunity, through good
design, appropriate coding standards, and proper testing and evaluation, to
ensure equal access.

2.7 Older Adult Users

Seniority offers many pleasures and all the benefits of experience, but aging can
also have negative physical, cognitive, and social consequences. Understanding
the human factors of aging can help designers to create user interfaces that facil­
itate access by older adult users (Fig. 2.4). The benefits include improved chances
for productive employment and opportunities to use writing, e-mail, and other
computer tools plus the satisfactions of education, entertainment, social interac­
tion, and challenge (Newell, 2011; Czaja and Lee, 2012) . Older adults are partic­
ularly active participants in health support groups. The benefits to society
include increased access to older adults, which is valuable for their experience
and tl1e emotional support they can provide to others.

F GURE 2.
HomeAssist is an assisted liv ing platform for older adu lts installed in homes is
Bordeaux, France. The tablet is used to show alerts (e.g ., when t he front doo r was
left opened) and rem inders but also to run a slide show of photog raphs when not in
use ( http ://phoe nix.in ri a. fr/resea rch-pro jects/ homeassist) .

70 Chapter 2 Universal Usability

The National Research Council ‘s report Human Factors Research Needs for an
Aging Population describes aging as

a nonuniform set of progressive changes in physiological and psychological
functionin g …. Average visual and auditory acuity decline considerably with
age, as do average strength and speed of response … . [People experience]
loss of at least some kind s of memory function, declines in perceptual flex­
ibility, slo,,ving of “stimulus encoding,” and increased difficulty in the
acquis ition of comp lex mental skills, … visual functions such as static visua l
acuity, dark adaptation, accommodation, contras t sens itivity, and per iph eral
vision decline, on average, with age. (Czaja, 1990)

This list has its di scouraging side, especially since older adults ma y have
multiple impairments, but many older adults increasingly experience only
moderate effects, allowing them to be active participants, even throughout tl1eir
ninetie s .

The further good news is that interface designers can do much to accommo­
date older adult users (Chisnell et al., 2006). Improved user experiences give older
adults access to the beneficial aspects of computing and network communication,
thu s bringing man y societal advantages. How many young peop le’s lives might
be enriched by e-mail access to grandparents or great-grandparents? How many
businesses might benefit from electronic consultations with experienced older
adults? How many government agencies, universities, medical centers, or law
firms could advance their goals from easily available contact with knowl edge­
able, older adult citizens? As a socie ty, how might we all benefit from the contin ­
ued creative work of older adults in literature, art, music, science, or philosophy?

As the world’s population ages, designers in many fields are adapting their work
to serve older adults, which can benefit all users. Baby boom ers have already begun
to pu sh for larger street signs, brighter traffic lights, and better nighttim e lighting to
make driving safer for drivers and pedestrians. Similarly, desktop, web, and mobile
devices can be improved for all users by providin g users with control over font
sizes, display contrast, and audio levels. Interfaces can also be designed with easier­
to-use pointing devices, clearer navigation path s, and consistent layout s to impro ve
access for older adults and every user (Hart et al., 2008; Czaja and Lee, 2012).

Considering older and disabled users during the design process often pro ­
duces novel designs (Newell, 2011), such as ballpoint pens (for people with
impair ed dexterity), cassette tape recorders (for blind users to listen to audio­
books), and auto-completion software (to reduce keystrokes). Texting interfaces
that suggest words or web-address comp letion were originally designed to ease
data input for older and disabled us ers but have become expec ted conveniences
or all users of mobile devices and web brow sers. These conveniences, which
reduce cognitive load, percep tual difficu lty, and motor control demands,
become vital in difficult environments, such as while traveling, injured, stressed,
or under pressure for rapid correct completion. Similarly, subtitles (closed

2.8 Children 71

captioning) and user-controlled font sizes were designed for users with hearing
and visual difficulties, but they benefit many users.

Researchers and designers are actively working on improving interfaces for
older adults (Czaja and Lee, 2012). In the United States, the AARP’s Older Wiser
Wired initiatives provide education for older adults and guidance for designers.
The European Union also has multiple initiatives and research support for com­
puting for older adults.

Networking projects, such as the San Francisco-based SeniorNet, are provid­
ing adults over the age of 50 with access to and education about computing and
the Internet “to enhance their lives and enable them to share their knowledge
and wisdom” (http:/ /www.seniomet.org/). Computer games are attractive for
older adults, as shown by the surprising success of Nintendo’s Wii, because they
stimulate social interaction, provide practice in sensorimotor skills such as eye­
to-hand coordination, enhance dexterity, and improve reaction time. In addi­
tion, meeting a challenge and gaining a sense of accomplishment and mastery
are helpful in improving self-image for anyone.

In our experiences in bringing computing to two residences for older adults, we
also encountered residents’ fear of computers and belief that they were incapable
of using computers. These fears gave way quickly after a few positive experiences.
The older adu lts, who explored e-mail, photo sharing, and educational games, felt
quite satisfied with themselves and were eager to learn more. Their newfound
enthusiasm encouraged them to try automated bank machines and supermarket
touchscreen kiosks. Suggestions for redesigns to meet the needs of older adults
(and possibly other users) also emerged – for example, the appeal of high-precision
touchscreens compared with the mouse was highlighted (Chapter 10).

In summary, making computing more attractive and accessible to older
adults enables them to take advantage of technology, enables others to benefit
from their participation, and can make technology easier for everyone. For more
information on this topic, check out the Human Factors & Ergonomics Society
(http:/ /www.hfes.org), which has an Aging Technical Group that publishes a
newsletter and organizes sessions at conferences.

2.8 Children

Another lively community of users is children, whose uses emphasize entertain­
ment and education (Hourcade, 2015). Even pre-readers can use computer­
controlled toys, music generators, and art tools. As they mature, begin reading,
and gain limited keyboard skills, they can use a wider array of desktop
applications, web services, and mobile devices (Foss and Druin, 2014). When
they become teenagers, they may become highly proficient users who often help
their parents or other adults. This idealized growth path is followed by many

72 Chapter 2 Universal Usability

children who have easy access to technology and supportive parents and peers.
However, many children without financial resources or supportive learning
environments struggle to gain access to technology. They are often frustrated
with its use and are endangered by threats surroUI,ding privacy, alienation, por­
nography, unhelpful peers, and malevolent strangers.

The noble aspirations of designers of children’s software include educational
acceleration, facilitating socialization with peers, and fostering the self-confidence
that comes from skill mastery (Fig. 2.5). Advocates of educational games promote
intrinsic motivation and constructive activities as goals, but opponents often
complain about the harmful effects of antisocial and violent games.

For teenagers, the opportunities for empowerment are substantial. They often
take the lead in emp loying new modes of communication, such as text messag­
ing on cellphones, and in creating cultura l or fashion trends tl,at surprise eve11
the designers (for example, playing with simulations and fantasy games and
participating in web-based virtual worlds).

Appropriate design principles for childr en’s software recognize young peo­
ple’s intense desire for the kind of interactive engagement that gives them con­
trol with appropriat e feedback and supports their social engagement with peers
(Bruckman et al., 2012; Fails et al., 2014). Designers also have to find the balance
between children’s desire for challenge and parents’ requirements for safety.

Children can deal w ith some frustra tions and with threatening stories, but
they also want to know that they can clear the screen, start over, and try again
without severe penalties. They don’t easily tolerate patronizing comments or

FIGURE 2.5

._., ….
•••

•

—–.. –

–‘GI’

Using Digita l Mysteries on a tablet, two elementary school children work together
to read information slips, group them, and create a sequence to answer the
quest ion “Who killed King Ted?” The blue pop-up pie menu allows the selection
of tools. A larger tabletop version allows larger groups to collaborate
(http ://w ww. reflectiveth inking .com).

2.8 Children 73

inappropriate humor, but they like familiar characters, exploratory environ­
ments, and the capacity for repetition. Younger children will sometimes replay a
game, reread a story, or replay a music sequence dozens of times, even after
adul ts have tired of it. While too mucl-1 “screen time ” can interfere wi th cl-1ild­
hood development, well-designed applications can help children with physical,
relationship, and emotional problems (Borjesson et al., 2015).

Some designers work by observing children and testing software with chil­
dre11, while the innovative approach of “children as our technology-des ign part­
ners” engages them in a long -term process of cooperative inquiry during which
children and adults jointly design novel products and services. A notable suc­
cessful product of working with children as design partners is the International
Children’s Digital Library, which offers 4500-plus of the world’s best children’s
books it1 SO-plus languages using an interface in 19 languages while supporting
low-and high -speed networks.

Designing for younger children requires attention to their limitations. Their
evo lving dexterity means that mo11se dragging, double-clicking, and sma ll tar­
gets cannot always be 11sed; their emerging literacy means that wri tten instruc­
tions and error messa ges are not effective; and their low capacity for abstractio n
means that complex sequences must be avoided unless an adult is involved.
Other concerns are short at tention spans and limited capaci ty to work with mul ­
tiple concep ts simul taneously . Designers of children’s software also have a
responsibi lity to attend to dangers, especially in web -based environments,
where parental control over access to violent, racist, or pornographic materials
is unfortunately necessary. Appropriate information for the education of chil­
dren about privacy issues and threats from strang ers is also a requirement.

The capacity for playful creativity in art, music, and writing and the value of
educational activities in science and math remain potent reasons to pursue chil­
dren’s software. Enabling them to make high-quality images, photos, songs, or
poems and then share them with friends and family can accelera te childr en’ s
personal and social development. Offering access to educa tional materials from
libraries, museums, government agencies, schools, and commerc ial sources
enriches their learning experiences and serves as a basis for children to construct
their own web resources, participate in collaborative efforts, and contribut e to
community-service projects.

Providing programming tools, such as the Scratch project (https:/ /sc ratch.
mit.edu/), and simulation-building tools enables older children to take on com­
plex cognitive challenges and construct ambitious artifacts for others to use.
These and other opportunities have motivated efforts (such as One Laptop Per
Child, http:/ /one .laptop.org/) to bring low-cost computers to children around
the world. Advocates point to enthusiastic adoption and tell stories of it1divid­
ual enablement. However, critics encourage a shift from the technology-centered
goals to greater attention to rich content, social engagemen t, parental guidance
materials, and effective teacher training.

74 Chapter 2 Universal Usability

2.9 Accommodating Hardware
and Software Diversity

In addition to accommodating different classes of users and skill levels, design­
ers need to support a wide range of hardware and software platforms. The rapid
progress of technology means that newer systems may have a hundred or a
thousand times greater storage capacity, faster processors, and higher­
bandwidth networks. However, designers need to accommoda te older devices
and deal with newer mobile devices that may have low-bandwidth connections
and small screens (Fig. 2.2).

The challenge of accommodating diverse hardware is coupled with the need
to ensure access through many generations of software. New operating systems,
web browsers, e-mail clients, and application programs should provide back­
ward compatibility in terms of their user -interface design and file structures.
Skeptics will say that this requirement can slow innovation, but designers who
plan ahead carefully to support flexible interfaces and self-defining files will be
rewarded with larger market shares .

For at least the next decade, three of the main technical challenges wi ll be:

• Producing satisfying and effective Internet interaction on high-speed (broad­
band) and slower (dial-up and som.e wireless) connections. Some techn ologi­
cal breakthroughs ha ve already been made in compression algorithms to
reduce file sizes for images, music, animations, and even video, but more
are needed. New technologies are needed to enable pre-fetching or sched­
uled downloads. User con trol of the amount of material downloaded for
each request could also prove benefici al (for example, allowing users to
specify that a lar ge image should be reduced to a smaller size, sent with
fewer colors, converted to a simplified line drawing, replaced with just a
text description, or downloaded at night when Internet charges are perhaps
lower).

• Responsive design enabling access to web services from large displays (3200 x 2400
pixels or larger) and smaller mobile devices (1024 x 768 pixels and s1rialler). Rev.rrit­
ing each webpage for different display sizes may produce the best quality,
but this approach is probably too costly and time-consuming for most web
providers. Software tools such as Cascading Style Sheets (CSS) allow design­
ers to specify their content in a way that enables automatic conversions for an
increasing range of display sizes.

• Supporting easy n1aintenance of or automatic conversion to 1r1ultiple languages.
Commercial operators recognize that they can expand their markets if
they can pr ovide access in multipl e langua ges and across multiple countri es.
This means isolating text to allow easy substitution, choosing appropriate

Researcher’s Agenda 75

metaphors and colors, and addressing the needs of diverse cultures
(Section 2.5).

Practitioner’s Summary

The good news is that when designers think carefully about the needs of diverse
users, they are like ly to come up wi th desktop, laptop, web, and mobile device
designs that are better for all users. A frequent path to success is through par­
ticipatory methods that bring designers in close and continuing contact with
their intended users. In some cases, improved tools and designs mean that one
design can be made so flexible that it can be presented automatical ly in text
(with a wide range of font sizes, colors, and contrast ratios ), in speech (with
male or female styles and at varying volumes and speeds), and in a wide range
of display sizes. Adjustments for different cuJtures, personalities, disabilities,
ages, input devices, and preferences may take more design effor t, bt1t the pay­
offs are in larger markets and more satisfied users. As for costs, with appro­
priate software tools, e-commerce providers are finding that a small additiona l
effort can expand markets by 20% or more. Although it can require additional
effort, designing for diverse users is cost effective and sometimes leads to major
breakthroughs.

Researcher’s Agenda

While market forces provide incentives for changes, additional legal and policy
interventions could speed progress in ensuring that desktop, laptop, web, and
mobile device user iI1terfaces continue to be accessib le to all . The expanding
worldwide research community, especially the ACM Special Interest Group on
Accessible Computing (SIGACCESS), hosts international conferences, publishes
journals, and encourages further research.

Research on diversity often brings innovations for all users; for example,
input devices for users wi th poor motor control can often help all passengers in
rough riding cars, buses, trains, or planes. Impro ved automated assistance for
conversions to diverse languages and cuJtures would improve designer produc­
tivity and facilitate changes to prices, dimensions, colors, and so on. Research on
cultural diversity is still needed about the acceptability by differing user groups
of novel features like emoticons, animation, personalization, gamification, and
musical accompaniments.

76 Chapter 2 Universal Usability

WORLD WIDE WEB RESOURCES

www. pearsonglobaleditions . com / shneiderman

Major suppliers offer diverse accessibi lity too ls:

• Apple: https://www.apple.com/accessibility/

• Microsoft: http://www .microsoft.com/enable/
• Google: https:/lwww.google.com/accessibility/

And many consumer-oriented and government groups provide assistance,
such as:

• AARP : http://www.aarp.org/home-family/personal-technology/
• Older Adults Technology Services: http://oats .org/
• U.S. Section 508: http://www.section508.gov/
• Resource list from Trace Center: http://trace.wisc.edu/resources/

Discussion Questions

1. Describe three populations of users with special needs. For each of these pop ­
ulations, suggest three ways current interfaces could be improved to better
serve them.

2. Suppose you need to design a system for users in two countries that are very
different from each other culturally. What are some of the design concerns
that you should be aware of to create a successful design?

3. In certain interfaces, it is necessary to inform users of an abnormal condition
or time-dependent information. It is important that the display of this infor­
mation catches the user’s attention. Suggest five ways a designer can success­
fully attract attention.

4. Name a piece of software you often use where it is easy to produce an error.
Explain ways you could improve the interface to better prevent errors.

5. What factors should designers co11sider to address the needs of individuals
with different physical abilities?

References

Blanck, P., eQuality: The Struggle for Web Accessibility by Persons with Cognitive Disabilities,
Cambridge University Press (2014).

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CHAPTER

Guideli@esi •

99 We want principles, not only developed-the work of the closet- ,,
but applied, which is the work of life.

Horace M ann
Thoughts , 1867

•• There never comes a point where a theory can be said to be true .
The most that anyone can claim for any theory is that it has shared

the successes of all its rivals and that it has passed at least one test ”
which they have failed .

CHAPTER OUTLINE
3. 1 Introduction

3.2 Guidelines

3.3 Principles

3.4 Theories

A. J. Ayer
Philosophy in the Twentieth Centur y, 1982

81

82 Chapter 3 Guidelines, Principles, and Theories

3.1 Introduction

User-in terface designers have accumulated a weal th of experience and research­
ers have produced a growing body of empirical evidence and theories, all of
which can be organized into:

1. Guidelines. Low- level focused advice about good practices and cautions
against dangers.

2. Principles. Middle -level strategies or rules to analyze and compare design
alternatives.

3. Theories. High-level widely applicable fra1neworks to draw on during
design and evaluation as well as to support comrnunicatio11 ai1d teaching.
Theories can also be predictive, such as those for pointing times by indi­
viduals or posting rates for community discussions.

In many con temporary sys tems, designers have a grand opportuni ty to
improve the user interface by applying es tablished guidelines to clean up clut­
tered displays, inconsistent layouts, and unnecessary text. These sources of debil ­
itating stress and frustration can lead to poorer performance, minor slips, and
ser ious errors, all contributing to job dissatisfaction and consumer resistance .

Guidelines, principles, and theories, which offer preventive medicine and
remedies for these problems, ha ve matured in recent yea rs (Grudin, 2012). Reli­
able methods for predicting pointing and input times (Chapter 10), better social
persuasion principles (Chapter 11), and helpful cognitive or perceptual theories
(Chapter 13) now shape research and guide design. International or national
standards, which could be described as commonly accepted and precisely
defined so as to be enforceable, are increasin gly influentia l (Carrol l, 2014).

This chapter begins with a sampling of guidelines for navigating, organizing
displays, getting user attention, and facilitating data entry (Section 3.2). Then
Section 3.3 covers some fundamental princip les of interface design, such as cop­
ing with user skill levels, task profiles, and interaction sty les. It presents the
Eigh t Golden Rules of Interface Design, explores ways of preventing user errors,
and closes with a section on ensuring human control while increasing automa­
tion. Section 3.4 reviews micro-HCI and macro-HCI theories of interface design.

3.2 Guidelines

From the earliest days of computing, interface designers have written down
guidelines to record their insights and to try to guide the efforts of future design­
ers. The ear ly App le and Microsoft guidelines, which were influen tial for

Interface Elements v

Labels

Images

Groups

Pickers

Tablt-s

Buttons

Switchts

Sliders

Maps

Movies

Date and Timer labE-ls

Menus

Watch Technologies

Resources

FIGURE 3.1

3.2 Guidelines 83

Pickers
Pickers display lists of items tl\at are navigable using the Digital Crown. They are meant to be a precise
and enga,ging way to mtinage selections. Pickers present their items in one of three styles:

List style displays text and image$ Stack style di.splays images in a card Sequence style displays one image

In a scrolling list Tius style displays stack sryle lnte,face. As che user from a sequence of Images. As the
the selected item and the previous scrolls, images are animated into user rurns the Oigitail CrO’lvn, the

and next Items If those Items are position with the se&ected Image on picker displays the previous or next

available. top. This style is best for photo image in the sequence without

browser interfaces. animations. This style Is good fot

custom picker interfaces built using

your own Images.

Example of Apple gu idelines for design ing menus for the iWatch.

desktop-interface designers, have been followed by dozens of guidelines documents
for the web ai1d mobile devices (Fig. 3.1) (see the list at the end of Chapter 1). A
guidelines document helps by developing a shared language and then promoting
consistency among 1nultiple designers in terminology usage, appearance, and
action sequences. It records best practices derived from practical experience or
empirical studies, with appropriate examples and counterexamples. The creation
of a guidelines document engages the design community in lively discussions
about input and output formats, action sequences, terminology, and hardware
devices (Lynch and Horton , 2008; Hartson and Pyla, 2012; Johnson, 2014).

Critics complain that guidelines can be too specific, incomplete, hard to
apply, and sometimes wrong. Propo11ents argt1e that building on experience
from design leaders contributes to steady improvements. Both groups recognize
the value of lively discussions in promoting awarerless.

The following four sections provid e exampl es of guidelines, and Section 4.3
discusses how they can be integrated into the design process. The examples
address some key topics, but they mere ly sample the thousands of guidelines
that have been written.

3.2. 1 Navigating the interface

Since navigation can be difficult for many users, providing c.lear ru.les is helpful.
The sample guidelines pr esented here come from the U.S. government’s efforts to

84 Chapter 3 Guidelines, Principles, and Theories

promote the design of informative webpages (National Cancer Institute, 2006), but
these guidelines have widespread application. Most are stated positively (“reduce
the user’s workload”), but some are negative (“do not display unsolicited win­
dows or graphics”). The 388 guidelines, which offer cogent examples and impre s­
sive research support, cover the design process, general principles, and specific
rules. This sample of the guidelines gives useful advice and a taste of their style:

Standardize task sequences. Allow users to perform tasks in the same sequence
and manner across similar conditions.

Ensure that links are descriptive. When using links, the link text should accu­
rately describe the link’s destination.

Use unique and descriptive headings. Use headings that are distinct from one
another and concep tuall y related to the conten t they describe.

Use radio buttons for rnutually exclusive choices. Provide a radio button control
when user s need to choose one response from a list of mutually exclusive
options .

Develop pages that will print properly. If users are likely to print one or more
pages, develop pages with widths that print properly.

Use thu111bnail i111ages to preview larger i111ages. When viewing full-size images
is not critica l, first pro vide a thumbnail of the image .

Guidelines to promote accessibility for t1sers with disabilities were included il,
the U.S. Rehabilitation Act. Its Section 508, with guidelines for web design, is pub ­
lished by the Access Board (http://www.access-board.gov/508.htm), an indepen­
dent U.S. government agency devoted to accessibility for people with disabilities.
The World Wide Web Co11sortium (W3C) adapted these guideline s (http:/ /www.
w3.org/TR/WCAG20/) and organized them into three priority levels, for which it
has provided automated checking tools. A few of the accessibility guidelines are:

Text alternatives. Provide text alternatives for any non-text content so that
it can be changed into other forms people need, such as large print, braille,
speech, syn,bol s, or simp ler languag e.

Tinie-based 111edia. Provide alternatives for time-based media (e.g., movies or
animations). Synchronize equivalent alternatives (such as captions or audi­
tory de scriptions of the visual track) \>vith the presentation.

Distinguishable. Make it easier for users to see and hear conten t, including
separating foreground from back groun d . Color is not used as the only visual
means of conveying information, indicating an action, prompting a response,
or distinguishing a visual element.

Predictable. Make Web pages appear and operate in predictable ways.

The goal of the se guidelines is to have webpage designers use features that per ­
mit users witl, disabilities to employ screen readers or other specia l technologies
to give them access to webpage content.

3.2 Guidelines 85

3.2.2 Organizing the display
Display design is a large topic with many special cases. An ear ly influential
guidelines document (Smith and Mosier, 1986) offers five high-level goals for
data display:

l. Consistency of data display. During the design process, the terminology,
abbreviations, formats, colors, capitalization, and so on should all be
standardized and controlled by use of a dictionary of these items.

2. Efficient information assimilation by the user. The format shou ld be familiar
to the opera tor and should be related to the tasks required to be performed
with the data. This objective is served by rules for neat columns of data,
left justification for alphanumeric data , right justification of integers,
lining up of decimal points, proper spacing, use of comprehensible labels,
and appropriate measurement units and numbers of decimal digits.

3. Mini1nal n1enwry load on the user. Users shou ld not be required to remember
information from one screen for use on another screen. Tasks sho uld
be arranged such that completion occurs with few actions, minimizing
the chance of forgetting to perform a step . Labels and common formats
shou ld be provided for novice or intermittent users.

4. Compatibility of data display ivith data entry. The format of displayed
information should be linked clearly to the format of the data entry.
Where possib le and appropriate, the output fields shou ld also act as
editable input fields.

5. Flexibility for user control of data display. Users should be able to get the
information from the display in the form most convenient for the task on
which they are working. For example, the order of columns and sorting
of rows sho uld be easily changeab le by the users.

This compact set of high-level objectives is a useful starting point, but each proj­
ect needs to expa nd these into application-spec ific and hardware-dependent
standards and practices.

3.2.3 Getting the user’s attention
Since substant ial information may be presented to users, exceptional conditions
or time-dependent information must be presented so as to attract attention
(Wickens et al., 2012). These guidelines detail several techniques for getting the
user’s attention:

• Intensity. Use two levels only, with limited use of high intensity to draw
atterltion.

• Marking. Underline the item, enclose it in a box, point to it with an arrow, or
use an indicator sttch as an asterisk, bullet , dash, plus sign, or X.

• Size. Use up to four sizes, with larger sizes attracting more attention.

• Choice of fonts. Use up to three fonts .

86 Chapter 3 Guidelines, Principles, and Theories

• Blinking. Use blinking displays (2-4 Hz) or blinking color changes w ith great
care and in limited areas, as it is distracting and can trigger seizures.

• Color. Use up to four standard colors, with additional colors reserved for
occasional use.

• Audio. Use soft tones for regular positive feedback and harsh sounds for rare
emergency condi tions.

A few words of caution are necessary. There is a danger of creating clut ­
tered displays by overusing these techniques. Some web designers use blink­
ing advertisements or animated icons to attract attention, but users almos t
uni versal ly disapprove. Animation is appreciated primarily when it provides
meaningfu l information, such as for a progress indicator or to show move ­
ment of files.

Novices need simple, logically organ ized, and well- labeled displays that
guide their actions. Expert users prefer limited labe ls on fields so data values are
easier to extract; subtle highlighting of changed values or positional presentation
is sufficient. Display formats must be tested with users for comprehensib ility.

Similarly highlighted items will be perceived as being related. Color-coding is
especially powerful in linking related items , but this use makes it more difficult to
cluster items across color codes (Section 12.5). User contro l over highlighting is
much appreciated, for example, allowing cellphone users to select the color for
contacts that are close family members or for meetings that are of high importance.

Audio tones, like the clicks in keyboards or cellphone ring tones, can provide
informative feedback about progress. Alarms for emergency conditions do alert
users rapidly, but a mechanism to suppress alarms must be provided. If several
types of alarms are used, testing is necessary to ensure that users can distinguish
between the alarm levels. Prerecorded or synthesized voice messages are a use­
ful alternative, but since they may interfere with communications between oper­
ators, they should be used cautiously (Section 9.3).

3.2.4 Facilitating data entry
Data-entry tasks can occupy a substantial fraction of users’ time and can be the
source of frustrating and potentially dangerous errors . Smith and Mosier (1986)
offer five high-leve l objectives as part of their guidelines for data entry
(Courtesy of MITRE Corporate Archives: Bedford, MA):

1. Consistency of data-entry transactions. Similar sequences of actions speed
learning.

2. Minin·,al input actions by user. Fewer input actions mean greater operator
productivity and -u sually-f ewer chances for error. Making a choice
by a sing le mouse selection or finger press, is preferred over typing in
a lengthy string of characters. Selecting from a list of choices eliininates

3.2 Guidelines 87

the need for memorization, structures the decision-making task, and
eliminates the possibility of typographic errors.
A second aspect of this guideline is that redundant data entry should be
avoided . It is annoying for users to enter the same information in two
locations, such as entering the billing and shipping addresses when they
are the same . Duplicate entry is perceived as a waste of effort and an
oppor tunit y for error.

3. Mini,nal n1e1nory load on users. When doing data entry, users should not be
required to remember lengthy lists of codes.

4. Con1patibility of data entry with data display. The format of data -entry
information should be linked closely to the format of displayed
infor1nation, such as dashes in telephone numbers.

5. Flexibility for user control of data entry. Experienced users prefer to enter in­
formation in a sequence that they can control, such as selecting the color
first or size firs t, when clothes shopping .

Guidelines documents are a wonderful star ting point to give designers the ben­
efit of experience (Fig. 3.2), but they will always need processes to facilitate edu­
cation, enforcement, exemption, and enhancement (Section 4.3).

PowerChart SNtcl’I Sl)ifliGuldu

Glyph

FIGURE 3.2

Small Glyph Medium Glyph

,. “‘I
Mut.ple l tcms Sde<:ted

film:
<dor•~soso I
wt : 12 P'.lt 25 Pit

Moltople Items Sdected
E()f{I;

•1r N ~ ~ a'lfomwtion CMW"IOt bt
kilded is leu thin 120 POI:.._ .- text only to —-,._,.,..,._

<dor•SOSOSO
sue: 12 Slit

lS"' I
Multiple Items Selected
film: -•S05050
sia: 16PMONTH/08: DAY/21

a. Command line

JAN
FEB
MAR
APR
MAY
JUN
JUL

Month AUG
SEP
OCT
NOV
DEC

MM/DD I 08/21

b. Form fill-in to
reduce typing

Day I 21 l~I

d. Pull-down menus offer meaningful
names and eliminate invalid values

MM~ DDl}I]

c. Improved form fill-in
to clarify and reduce
errors

◄ August ►
s M T w T F s

1 2 3 4 5 6

7 8 9 10 11 12 13

14 15 16 17 18 19 20

(ID 22 23 24 25 26 27

28 29 30 31

e. 2-D menus to provide
context, show valid dates, and
enable rapid single selection

Form fill-in When data en try is required, menu selection alone usually be­
comes cumbersome, and form fill-in (also called fill in the blanks) is appropriate.
Users see a display of related fields, move a cursor among the fields, and enter
data where desired. With the form fill-in interaction style, users must under­
stand the field labels, know the permissible value s and the data-entry method,
and be capable of responding to error messages. Since knowledge of the key­
board, labels, and permissible fields is required, some training may be neces­
sary. This interaction sty le is most appropriate for knowledgeable intermittent
users or frequent users. Chapter 8 provides a thorough treatment of form fill-in.

Command language For frequent users, command languages (discussed in
Section 9.4) provide a strong feeling of being in control. Users learn the syr,­
tax and can often express complex possibilities rapidly without having to read
distracting prompts. However, error rates are typically high, training is neces­
sary, and retention may be poor. Error messages and online assistance are hard
to provide because of the diversity of possibilities. Command languages and
query or programming languages are the domain of expert frequent users, who
often derive great satisfaction from mastering a complex language. Powerful
advantages include easy scripting and history keeping.

3.3 Principles 95

Natural language Increasingly, user interfaces respond properly to arbitrary
spoken (for example, Siri on the Apple iPhone) or typed natural-language state­
ments (for example, web search phrases). Speech recognition can be helpful
with familiar phrases such as “Tell Catl1erine that I’ll be there i11 ten minutes,”
but with novel situations users may be frustrated with the results (discussed in
Chapter 9).

Blending several interaction styles may be appropriate when the required
tasks and users are diverse. For example, a form fill-in interface for shopping
checkout can include menus for items such as accepted credi t cards, and a
direct-manipulation environment can allow a right-click that produces a pop-up
menu with color choices. Also, keyboard commands can provide shortcuts for
experts who seek more rapid performance than mouse selection.

Increasingly, these five interaction styles are complemented by using context,
sensors, gestures, spoken commands, and going beyond the screen to include
enriched environments that enable users to activate doors, change sound volume,
or turn on faucets. These enriched environmen ts, such as those found in au tomo­
biles, game arcades, projected displays, wearable interfaces, musical instrumen ts,
and sound spaces, go beyond the desktop and mobile devices to produce playful
and useful effects. The expansion of user interfaces into clothing, furniture, build­
ings, implanted medical devices, mobi le platforms such as drones, and the Inter­
net of Things enriches traditional strategies and expands the design possibilities.

Chapters 7-9 expand on the constructive guidance for using the different
interaction styles outlined here , and Chapter 10 describes how input and output
devices influence these interaction styles. Chapter 11 deals with interaction
when using collaborative interfaces and participating in soc ial media.

3.3.4 The Eight Golden Rules of Interface Design
This section focuses attention on eight principles, called “golden rules,” that are
applicable in most interactive systems and enriched environments. These prin­
ciples, derived from experience and refined over three decades, require valida­
tion and tuning for specific design domains. No list such as this can be complete,
but it has been well received as a useful guide to students and designers. The
Eight Golden Rules are:

1. Strive for consistency. Consistent sequences of actions should be required
in simi lar situations; identical terminology should be used in prompts,
menus, and help screens; and consistent color, layout, capitalization, fonts,
and so on, should be emp loyed throughout. Exceptions, such as required
confirmation of the delete command or no echoing of passwords, should be
comprehensible and limited in number.

2. Seek universal usability. Recognize the needs of diverse users and design
for plasticity, facilitating transformation of content. Novice to expert differences,

96 Chapter 3 Guidelines, Principles, and Theories

age ranges, disabilities, international ,,ariations, and technological diversity
each enrich the spectrum of requirements that guides design. Adding
features for novices, such as explanations, and features for experts, such
as shortcuts and faster pacing, enriches the interface design and improves
perceived quality.

3. Offer informative feedback. For every user action, there sho uld be an interface
feedback. For frequent and minor actions, the response can be modest,
whereas for infrequent and major actions, the response should be more
substantial. Visual presentation of the objects of interest provides a
convenient environment for showing changes explicitly (see the discussion
of direct manipulation in Chapter 7) .

4. Design dialogs to yield closure. Sequences of actions should be organized
into groups with a beginning, middle, and end. Informative feedback
at the completion of a group of actions gives users the satisfactio n of
accomplishment, a sense of relief, a signal to drop conting ency plans from
their minds, and an indicator to prepare for the next group of actions. For
examp le, e-commerce websites move users from selecting products to
the checkout, ending with a clear confirmation page that completes the
transaction.

5. Prevent errors. As much as possible, design the interface so that users
canno t make serious errors; for example, gray out menu items that are
not appropriate and do not allow alphabetic characters in numeric entry
fields (Section 3.3.5). If users make an error, the interface should offer
simple, constr uctive, and specific instructions for recovery. For example,
users should not have to retype an entire name-address form if they enter
an invalid zip code but rather should be guided to repair only the faulty
part. Erroneous actions should leave the interface state unchanged, or the
interface should give instructions about restori ng the sta te.

6. Permit easy reversal of actions. As much as possible, actions should be
reversible. This feature relieves anxiety, since users know that errors can
be undone, and erlcourages exploration of unfamiliar options. The units of
reversibility may be a single action, a data-entry task, or a complete group of
actions, such as entry of a name-address block.

7. Keep users in control. Experienced users strongly desire the sense that they
are in charge of the interface and that the interface responds to their actions.
They don’t wan t surprises or changes in familiar behavior, and they are
annoyed by tedious data-entry sequences, difficulty in obtaining necessary
information, and inability to produce their desired result.

8. Reduce short-te·mt memory load. Humans’ limited capacity for information
processing in short-term memory (the rule of thumb is that people can
remember “seven p lus or minus two chunks” of information) requires that
designers avoid interfaces in which users must remember information from

3.3 Principles 97

one display and then use that information on another display. It means that
cellphones should not require reentry of phone numbers, website loca­
tions should remain visible, and lengthy forms should be compacted to fit a
single display.

These underlying principles must be interpreted, refined, and extended for
each environment. They have their limitations, but they provide a good start ­
ing point for mobile, desktop, and web designers. The principles presented in
the ensuing sections focus on increasing users’ productivity by providing sim ­
plified data -entry procedures, comprehensible displays, and rapid informa­
tive feedback to increase feelings of compe tence, mastery, and control over the
system.

3.3.5 Prevent errors

•• There is no medicine against death, and agains t error no ru le has been found. ,,

Sigmund Freud
(inscription he wrote on his portrait)

The importance of error prevention (the fifth golden rule) is so strong that it
deserves its own section. Users of cellphones, e-mail, digital cameras, e-commerce
websites, and other interactive systems make mistakes far more frequently than
might be expected.

One way to reduce the loss in productivity due to errors is to improve the
error messages provided by the interface. Better error messages can raise suc­
cess rates in repairing the errors, lower future error rates, and increase subjec­
tive satisfaction. Superior error messages are more specific, positive in tone,
and constructive (telling users vvhat to do rather than merely reporting the
problem). Rather than using vague (? or WHAT?) or hostile ( ILLEGAL OPERATION or
SYNTAX ERROR) messages, designers are encouraged to use informative messages,
such as PRI NTER IS OFF, PLEASE TURN IT ON or MONTHS RANGE FROM 1 TO 12.

Improved error messages, however, are only helpful medicine. A more effec­
tive approach is to pre, 1ent the errors from occurring. This goal is more attain­
able than it may seem in many interfaces.

The first step is to understand the nature of errors. One perspective is that
people make mistakes or slips (Norman, 1983) that designers can help them to
avoid by organizing scree11s and me11us functionall y, designing commands and
menu choices to be distinctive, and making it difficult for users to take irrevers­
ible actions. Norman also offers other guidelines, such as providing feedback
about the state of the interface (e.g., changing the cursor to show whether a map
interface is in zoom-in or select mode) and designing for consistency of actions
(e.g., ensuring that yes/no buttons are always displayed in the same order).

98 Chapter 3 Guidelines, Principles, and Theories

Norman’s analysis provides practical examples and a useful theor y. Additional
design techniques to reduce errors include the following:

Correct actions. Industrial designers recognize that successfu l products must be
safe and must prevent users from dangerously incorrect usage of the products.
Airplane engines cannot be put into reverse until the landing gear has touched
down, and cars canno t be put into reverse while traveling for,,.,ard at faster than
five miles per hour. Similar principles can be applied to interactive sys tems- for
example, inappropriate menu items can be grayed out so they can’t be inad ­
vertently selected, and web users can be allowed to simply click on the date on
a calendar instead of having to type in a month and day for a desired air)jne
flight departure. Likewise, instead of having to enter a 10-digit phone number,
cellphone users can scroll through a list of frequent ly or recently dialed num ­
bers and select one with a single button press. A variant idea is to provide users
with auto-completion for typing words, selecting from menus, or entering web
addresses.

Complete sequences. Sometimes an action reqt1ires several steps to reach comp le­
tion. Since users may forget to complete every step of an action, designers may
attempt to offer a sequence of steps as a single action. In automobiles, drivers
do not have to set two switches to signa l a left turn; a single switch causes both
(front and rear) tum-signal ligh ts on the left side of the car to flash. Likewise,
when a pilot throw s a swi tch to lower the landing gear, hundreds of mechanical
steps and checks are invoked automatically.

As another example, users of a text ed itor can indicate that all section titles are
to be centered, set in uppercase letters, and underHned without having to make a
series of selections each time they enter a section title. Then if users want to change
the title style-for example, to eliminate underlining – a single change will guar­
antee that all section titles are revised consistently. As a final example, an air-traf­
fic controller may formulate plans to change the altitude of a plane from 14,000
feet to 18,000 feet in two increments; after raising the p lane to 16,000 feet,
however, the controller may get distracted and fail to complete the action. The
controller should be able to record the plan and then have the computer prompt
for completion. The notion of complete sequences of actions may be difficult to
implement because users may need to issue atomic actions as well as complete
sequences . In this case, users should be allowed to define sequences of their
own. Designers can gather information about potential complete sequences by
studying sequences of actions that people actually take and tlle patterns of
errors that peop le actually make.

Thinking about universal usability also contributes to reducing errors-for
example, a design with too many small buttons may cause unacceptably high
error rates among older users or otllers with limited motor control, but enlarg­
ing the buttons will benefit all users. Section 4.6 addresses the idea of logging
user errors so designers can continuously improve designs.

3.3 Principles 99

3.3.6 Ensuring human control while increasing automation

The guidelines and principles described in the previous sections are often
devoted to simplifying the users’ tasks . Users can then avoid routine, ted iou s,
and error-prone actions and can concentrate on making critical decisions, select­
ing alternatives if the original approach fails, and acting in unanticipated situa­
tions. Users can also make subjective value-based judgm ents, request help from
other human s, and develop new so lution s (Sanders and McCormick, 1993).
(Box 3.3 provides a detailed comparison of human and machine capabilities.)

Computer system designers have generally been increasing the degree of auto­
mation over time as procedures become more standardized and the pressure for
productivity grows. With routine tasks, automation is desirable, since it red uces
the potential for errors and the users’ workload (Cummings, 2014). However,
even with increased automation, informed designers can still offer the predictable
and controllable interfaces that users usually prefer. The human supervisory role
needs to be maintained because the real world is an open system (that is, a nonde­
numerable number of unpredictable events and system failures are possible). By
contrast, computers constitute a closed system ( only a denumerable number of nor-

mal and failure situations can be accommodated in hardware and software).

BOX 3.3
Relative capabilities of humans and machines.

Hum ans Generally Bett er

• Sense-making from hearing,
sight, touch, etc.

• Detect familiar signals in noisy
background

• Draw on experience and adapt
to situations

• Select alternatives if original
approach fails

• Act in unanticipated situations

• Apply principles to solve varied
problems

• Make subjective value-based
judgments

• Develop new solutions

• Use information from external
environment

• Request help from other humans

Machine s Generally Bett er

• Sense stimu li outside human’s
range

• Rapid consistent response for
expected events

• Retrieve detailed information
accurately

• Process data with anticipated
patterns

• Perform repetitive actions
reliably

• Perform several act ivities
simultaneously

• Maintain performance over
time

100 Chapter 3 Guidelines, Principles, and Theories

For example, in air-traffic control, common actions include changes to a
plane’s altitude, heading, or speed. These actions are well understood and
potentially can be automated by scheduling and route-allocation algorithms,
but the human controllers must be present to deal with the highly variable and
unpredictable emergency situations. An automated system might deal success­
fully with high volumes of traffic, but what would happen if the airport man­
ager closed a runway because of turbulent weather? The controllers would
have to reroute planes quickly. Now suppose that one pilot requests clearance
for an emergency landing because of a failed engine, while another pilot reports
a passenger with chest pains who needs prompt medical attention. Value-based
judgment, possibly with participation from other controllers, is necessary to
decide which plane should land first and how much costly and risky diversion
of normal traffic is appropriate. Air-traffic cor1trollers cannot just jump into ar1
emergency; they must be intensely involved in the situation as it develops if
they are to make informed and rapid decisions. In short, many real-world situ ­
ations are so complex tha t it is imp ossible to an ticipat e and program for every
contingency; human judgment and values are necessary in the decision­
making process.

Another example of the complexity of life-critical situations in air -traffic con­
trol was illustrated by an incident on a plane that had a fire on board. The con­
troller cleared other traffic from the flight path and began to guide the plane in
for a landing, but the smoke was so thick that the pi lot had troub le reading his
instruments. Then the onboard transponder burned out, so the air-traffic con­
troller could no longer read the plane’s altitude from the situation display. In
sp ite of these multiple failures, the controller and the pilot managed to bring
down the plane quickly enough to save the lives of many-but not all-of the
passengers. A computer could not have been programmed to deal with this par ­
ticul ar unexpected series of events.

A tragic outcome of excess of aut omation occurred during a flight to Ca li,
Colombia. The pilots re lied on the automatic pilot and failed to realize that the
plane was making a wide turn to return to a location that it had already passed.
When the ground-collision alarm sounded, the pilots were too disoriented to
pull up in time; they crashed 200 feet below a mountain peak, killing all but four
peop le on board.

The goal of design in many applications is to give users sufficient information
about current status and activities to ensure that, when intervention is neces­
sary, they have the knowledge and the capacity to perform correctly, even under
partial failures (Endsley and Jones, 2004). The U.S. Federal Aviation Agency
stresses that designs should place the users in contro l and automate only to
“improve system performance, without reducing human involvement” (U.S.
FAA, 2012). These standards also encourage managers to “train users when to
question automation .”

3.3 Principles 101

The entire user interface must be designed and tested not only for normal situ­
atio11s but also for as wide a range of anomalous situations as can be anticipated.
An extensive set of test conditions might be included as part of the requirements
document. Users need to have enough information that they can take responsi­
bility for their actions. Beyond decision making and handling of failures, the
users’ role is to improve the interface design.

Advocates of increased autonomy, such as in driverless cars or unmanned
aircraft, believe that rapid autonomous responses improve performance and
produce fewer errors. However, autonomy has risks for unanticipated situa­
tions, such as changing weather or unusual trading activity. In 2015, Toyota
shifted its driverless car research from autonomous designs to ones that leave
drivers in control. The dangers of unanticipated situations for Unmanned Aerial
Vehicles (UAVs) resulted in shifting to Remotely Piloted Vehicles (RPVs) with
human control to improve reliability. While autonomy has its benefits, designs
that allow human supervisory control, activity logging, and the capacity to
review logs after failures appear to improve performance.

In costly business situations, such as high-speed stock market trading, clarify­
ing responsibility for failures could lead to improved designs. Ensuring account­
ability and liability in advance can encourage designers to think more carefully
abou t potential failures. Advocates of “algorithmic accountab ility” want devel­
opers who implement systems such as Google’s search rankings or employee
hiring systems to enable open access so as to limit bias and expose errors.

Questions about integrating automation with human control also emerge in
consumer product user interfaces. Many designers are eager to create an auton­
omo us agent that knows people’s likes and dislikes, makes proper inferences,
responds to novel situations, and performs competent ly with litt le guidance.
They believe that human-human interaction is a good model for human­
computer interaction, and they seek to create computer-based partners, assis­
tants, or agents.

By contrast, many designers believe that tool-like interfaces are often more
attractive than autonomous, adaptive, or anth ropomorphic agents that carry out
the users’ intentions and anticipate needs. The agent scenarios may show a bow­
tied butler-like human, like the helpful young man in App le Computer’s famous
1987 video on the Knowledge Navigator. Microsoft’s ill-fated 1995 BOB program
used cartoon characters, while its much-criticized Clippit, nicknamed Clippy,
character was also withdrawn. Human -like bank machines or postal-service sta­
tions have largely disappeared, but avatars representing users, not computers,
in game-playing and 3-D socia l environments have remained popular; users
appear to enjoy the theatrical experience of creating a new identity, sometimes
with colorful hair and clothes (Section 7.6).

The success of Apple’s Siri’s speech recognition and personality-rich voice
response system shows that with careful development, useful tools ca11 be

102 Chapter 3 Guidelines, Principles, and Theories

deve loped, but there is little evidence of the benefit of a talking face (Moreno
and Mayer, 2007). Robot designers have perennially used human and animal
forms as an inspiration, encouraging some researchers to pursue human-like
robots for care of older adults or as team members in work situations. These
designs attract journalists and have entertainmen t value but have yet to gain
widespread acceptance.

A variant of the agent scenario, which does not include an ai1thropomorphic
realization, is that the compu ter program has a built-in user model to guide at,
adaptive interface. The program keeps track of user performance and adapts the
interface to suit the users’ needs. For example, when users begin to make menu
selections rapidly, indicating proficiency, advanced menu items may appear.
Au tomatic adaptations have been proposed for interface features such as the
content of menus, order of me11u items, and type of feedback (graphic or tabu ­
lar) . Advocates point to video games that increase the speed or number of dan ­
gers as users progress through game levels. Ho\.vever, games are notably
different from most work situation s, where users bring their goals and motiva­
tion s to accomplish tasks.

There are opportunities for adaptive user models to tailor designs (such as for
e-mail spam filters or search results ranking), but unexpected interface behavior
can have nega tive effects that discourage use. If adaptive sys tems make surpri s­
ing cha11ges, such as altering the search results ranking, users may be puzzled
about what has happened. Users may become anxious because they cannot pre ­
dict the next change, interpret what has happened, or return to the previous
state . Users may also be annoyed if a one-time purchase of a children’s book as
a gift leads to repeated promotions of more children’s books.

An application of user mode ling is reco1nmender systems in web applications.
In this case, there is no agent or adaptation in the interface, but the program
aggregates information from multiple sources in some (often proprietary) way.
Su.ch approaches have great practical val ue such as suggesting movies, books,
or music; users are often intrigued to see what suggestions emerge from their
purchasing patterns. Amazon.com and other e-commerce companies success ­
fully suggest that “customers who bought X also bought Y.”

The philosophical alternative to agen ts and user mod eling is to design com­
prehensible sys tems that provide consistent interfaces, user control, and predict­
able behavior. Designers who emphasize a direct -manipulation style believe that
users have a strong desire to be in control and to gain mastery over the system,
which allows them to accept responsibility for their actions and derive feelings of
accomplishment (Shneiderman, 2007). Historical evidence suggests that users
seek comprehensible and predictable sys tems and shy away from those that are
complex or unpredictable; for example, pilots may disengage automatic piloting
devices if they perceive that these systems are not performing as they expect.

Agent advocates promote au tonomy, but this means they must take on the
issue of responsibility for failures. Who is responsible when an agent viola tes

Settings

@ PERSONALIZATION

Background

Colors

Lock screen

Themes

Start

FIGURE 3.4

3.3 Principles 103

I Find a setti ng

Start

Show most used apps

tll) On

Show recently added apps

tll) On

Use Start full screen

<• ) Off

□

Show recently opened items in Jump Lists on Start
or the taskbar

tll) On

Choose which folders appear on Start

X

Windows 10 system preferences include control pane ls for personalization. Here
we see the Start options, which allow users to control what items will display in the
Start menu and taskbar .

copyright, invades privacy, or destroys data? Agent designs might be better
received if they supported performance monitoring while allowing users to
examine and revise the current user model.

An alternative to agents with user models may be to expand the control-panel
model. Computer control panels (sometimes called settings, options, or prefer­
ences), like automobile cruise-control mechanisms and television remote con­
trol s, are designed to convey the se11se of control that users seem to expect. Users
employ contr ol panels to set physical parameters, such as the cursor blinking
speed or speaker volume, and to establish personal preferences such as time/
date formats, color schemes, or the content of start menus (Fig. 3.4). Some soft­
ware pa ckages allow users to se t param eters such as the speed of play in games.
Use rs start at layer 1 and can then choose when to progre ss to higher levels;
often they are content to remain experts at layer 1 of a complex interface rather
than dealing with the uncert ainties of higher layers. More elaborate control pan­
els exist in style shee ts of word processors, specifica tion boxes of query facilities,
and sliders of information-visualization tool s.

104 Chapter 3 Guidelines, Principles, and Theories

3.4 Theories

One goal for the discipline of human-computer interaction is to go beyond the
specifics of guidelines and build on the breadth of principles to develop tested,
reliable, and broadly usefu l theories. Of course, for a topic as large as user­
interface design, many theorie s are needed (Carroll, 2003; Rogers, 2012;
B0dker, 2015).

Some theories are descriptive; these are helpful in developing consistent termi­
nology and useful taxonomies, for objects and actions, thereby supporting col­
laboration and training. Other theories are explanatory, describing sequences of
events and, where possible, cause and effect, making interventions possible.
Still other theories are prescriptive, giving designers clear guidance for their
choices. Finally, the most precise theories are predictive, enabling designers to
compare proposed designs for execution time, error rates, conversion rates, or
trust levels.

Another way to group theories is according to the types of skills involved,
such as n1otor (pointing with a mouse), perceptual (finding an item on a display),
or cognitive (planning the sequence of steps needed to pay a bill) (Norman, 2015).
Motor skill performance predictions are well established and accurate for pre­
dicting keystroking or pointing times (see Fitts's Law, Section 10.3). Perceptual
theories have been successful in predicting reading tunes for free text, lists, for­
matted displays, and other visual or auditory tasks. Cognitive theori es, involv­
ing sho rt-term , working, and long -term memory, are central to problem solvit1g
and play a key role in understanding productivity as a function of system
response time (Chapter 12). However, predicting performance on complex cog­
nitive tasks (combinations of sub tasks) is especially difficult because of the
many stra tegies that might be employed and the mai1y opportunities for goit1g
astray. The ratio of tunes needed to perform complex tasks between novices and
experts or between first -tune and frequent users can be as high as 100 to 1. Actu­
ally, the contras t is even more dramatic because novices and first-time users
often make errors and are unable to complete the tasks.

Web designers have emphasized information-architecture theories with navi ­
gation as the keys to user success. Web users can be considered as foraging for
informati on, and therefore the effective ness of the infor1nation scent of links is the
issue (Pirolli, 2007). A high-quality link, relative to a specific task, gives users a
good scent (or indication) of what is at the destination. For example, if users are
trying to find a demonstration of a sofu ,vare package, a link with the text
"download demo" has a good scent. The challenge to designers is to under­
stand user tasks well enough to design a large website such that users will be
able to find their way successfu lly from a home page to the right destination,
even if it is three or four clicks away. Information-foraging theory attempts to

3.4 Theories 105

BOX 3.4
Multiple theory types that researchers and designers consider when evaluating user
interfaces.

By Theory Type

• Descriptive Describes user interfaces and their uses with consistent
termino logy and taxonomies

• Explanatory Describes sequences of events with causal relationships

• Prescriptive Offers guide l ines for designers to make decisions

• Predictive Enables comparison of design alternatives based on
numeric predictions of speed or errors.

By Human Capacity

• Motor

• Perceptual

• Cognitive

Ski ll in pointing, clicking, dragging, or other movements

Visual, auditory, tacti le, and other human sensory inputs

Problem solving with short- and long-term memory

predict user success rates given a set of tasks and a website so as to guide
refinements.

Taxononii es can be an important part of descriptive and explanatory theo­
ries. A taxonomy imp oses order by class ifying a complex se t of phenomena
into understandable categories. For example, a taxonomy might be created
for different kinds of input devices: direct versus indirect, linear versus
rotary, 1-, 2-, 3- or higher-dimensional, and so on (Card et al., 1990). Other
taxonomies might cover tasks (structured versus unstructured, novel versus
regular) or user-interface styles (direct manipulation, menus, form fill-in).
An important class of taxonomies has to do with the individual differences
among users, such as personality styles (convergent versus divergent, field­
dependent versus independent), technical aptitudes (spatial visuali zation,
reasoning), and user experience levels (novice, knowledgeable, expert).
Taxonomies facilitate useful comparisons, organize topics for newcomers,
guide designers, and often indicate opportunities for novel products-for
example, a task by type taxonomy organi zes the information visuali zation s
in Cl1apter 16.

Any theory that might help designers to predict performance for even a lim­
ited range of users, tasks, or designs is a contribution. At the moment, the field
is filled with hundreds of theories competing for attention while being refined
by their promoters, extended by critics, and applied by eager and l1opeful- but
skeptical-designers (Carroll, 2003, 2014; Rogers, 2012). This development is
healthy for the growing discipline of human-computer interaction, but it means

106 Chapter 3 Guidelines, Principles, and Theories

that practitioners must keep up with the rapid developments not only in soft­
ware tools and design guidelines but also in theories. Critics raise two chal­
lenges:

1. Theories should be 1nore central to research and practice. A good theory should
guide researchers in understanding relationships between concepts and
generalizing results. It should also guide practitioners when making
design tradeoffs for products. The power of theories to shape design is
most apparent in focused theories such as Fitts's Law; it is more difficult
to demonstrate for explanatory theories, whose main impact may be in
educating the next generation of designers .

2. Theories should lead rather than lag behind practice. Critics remark that too often
a theor y is used to explain what has been produced by commercial product
designers. A robust theory should predict or at least guide practitioners in
designing new products. Effective theories sl1ould suggest novel products
and services while helping to refine existing ones.

Another direction for theoreticians is to predict the subjective satisfaction or
emotional reactions of users. Researchers in media and advertising have recog­
nized tl1e difficulty of predicting emotional reactions, so they complement theo­
retical predictions with their intuitive judgments and extensive market testing
(Nahl and Bilal, 2007).

Broader theories of small-group behavior, organizational dynamics, and soci­
ology are proving to be useful in understai1ding social media and collaborative
interfaces (Chapter 11). Similarly, the methods of antluopology or social psy­
chology may be helpful in understanding technology adoption and overcoming
barriers to new technology that cause resistance to change.

There may be "nothing so practical as a good theory," but coming up wi th an
effective theory is often difficult. By definition, a tl1eory, taxonomy, or model is
an abstraction of reality and therefore must be incomplete. However, a good
theory should be understandable, produce similar conclusions for all who use it,
and help to solve design problems. This section reviews a range of descriptive
and explanatory theories.

3.4.1 Design-by-levels theories
One approach to developing descriptive theories is to separa te concepts accord­
ing to levels . Such theories have been helpful in software engineering and net ­
work design. An appealing and easily comprehensible design-by-levels theory
for interfaces is the four-level concep tual, seman tic, syn tactic, and lexical theory
(Foley et al., 1995):

1. The conceptual level is the user's "menta l model" of the interactive system.
Two menta l models for image crea tion are paint programs that manipulate
pixels and drawing programs that operate on objects. Users of paint
programs think in terms of sequences of actions on pixels and groups of

3.4 Theories 107

pixels, while users of drawing programs think in terms of sequences of
actions on objects and groups of objects. Decisions about mental models
affect each of the lower levels.

2. The seniantic level describes the meanings conveyed by the user's input
and by the comp ut er's output display. For example, deleting an object in a
drawing program could be accomplished by undoing a recent action or by
invoking a delete -object action. Either action should eliminate only a single
object and leave the rest untouched.

3. The syntactic level defines how the user actions that convey semantics are
assembled into comp lete sen tences to perform cer tain tasks . For example,
the delete-files action could be invoked by dragging an object to a trash can
followed by a click in a confirmation dialog box.

4. The lexical level deals with device dependencies and with the precise mecha­
nisms by which users specify the syntax (for example, a function key or a
mouse double-click within 200 milliseconds).

This four-level theory is convenient for designers because its top -down
nature is easy to explain, matches the software architecture, and allows for use­
ful modularity during design. Over the years, the success of graphica l direct­
manipulation interfaces has shifted attention up to the conceptual level, which
is closest to the task domain (Parusl1, 2015). For example, designers of personal
financial interfaces often use direct-manipulation it1terfaces. These interfaces
build on the users' mental model of writing checks by showing the image of a
check for users to fill in. The same image of a check serves as the query template
so users can specify dates, payees, or amounts.

Increasingly, actions are shown by novel visual representations (for example,
a trash can for deletion or a play button to start playing a video). Users have to
learn the semantics (e.g., that they can recover a file by opening up the trash can
or stop a video by clicking on the pause button), but if the designers choose
familiar objects to associa te with the actions, users can quickly acquire the cor­
rect mental model for operating the user interface. Of course, users also have to
learn the syntax of dragging objects or clicking to initiate the actions, but these
mechanisms are common ly used and have become we!J known.

The idea of design-by-levels is successf ul even in more comp lex systems with
many objects and actions. For example, the human body can be discussed in
terms of neural, muscular, skeletal, reproductive, digestive, circulatory, and
other su.bsystems, which in tum mjght be described in terms of organs, tissues,
and cells. Most real-world objects have similar decompositions: buildings into
floors, floors into rooms , rooms into doors/walls/windows, and so on. Similarly,
movies can be decomposed into scenes, scenes into shots, and shots into dia­
logue, images, and sounds. Since most objects can be decomposed in many ways,
the designer's job is to create compre hensible and memorable leve ls of objects.

In parallel with the decomposition of objects, designers need to decompose
complex actions into several smaller actions. For example, a baseball game has

108 Chapter 3 Guidelines, Principles, and Theories

innings, pitches, runs, and outs, and a building-construction plan can be
reduced to a series of steps such as surveying the property, laying the founda­
tion, building the frame, raising the roof, and completing the interior. Most
actions can also be decomposed in many ways, so again the designer's job here
is to create comprehensible and memorable levels of actions. The goal of sim­
plifying interface concepts while presenting visua l representations of the
objects and actions involved is at the heart of the direct-manipulation approach
to design (Chapter 7).

When a complete user-interface design has been made, the user ta sks can
be described by a series of actions. These precise descriptions can serve as a
basis for predicting the time required to perform tasks by simply counting up
the number of milliseconds needed to complete all the steps. For examp le,
resizing a pl1oto may require several mouse drags, selections of menu items,
clicks on dialog box buttons, and typing of dimensions, but each of these
actions takes a predictable amount of time. Several researchers have success­
fully predicted the tim e required for complex tasks by adding up the tim es
required for each componen t action. This predictive approach, based on goals,
operators, methods, and selection rules (GOMS), decomposes goa ls into many
operators (actions) and then into methods. Users apply selection rules to
choose among alterna te methods for achieving goals (Card et al., 1983;
Baumeister et al., 2000).

The GOMS approach works best when the users are expert and frequent
users who are working on their own, ful ly focused on the task, and make no
mistakes. Advocates of GOMS have developed software tools to simplify and
speed up the modeling process in the hope of increasing usage (John, 2011).
Critics complain that broader theories are needed to predict novice user beha v­
ior, the transition to proficiency, the rate of errors, and retention over time.

Designers have discovered that using design-by-levels theories forces clear
definitions of the high -Je,rel objects and actions, which are gathered from listen­
ing to the language used in the task domain. Music can be thought of as songs,
organized by artists, albums, and gen res. Users can find a song and then play it
or add it to a play list. The clarity of this conceptual structure earned it a patent
and has stimulat ed multiple comme rcial successes.

3.4.2 Stages-of-action theories
Another approach to forming explanatory theories is to portray the stages of
action that u sers go through in using interactive products su ch as informati on
appliances, web interfaces, or mobile devices (e.g., music players). Normai1
(2013) offers seven stages of action, arranged in a cyclic pattern, as an explana ­
tory theory of human-computer interaction:

1. Forming the goal

2. Forming the intention

3.4 Theories 109

3. Specifying the action

4. Executing the action

5. Perceiving the system state

6. Interpreting the system state

7. Evaluating the outcome

Some of Norman's stages correspond roughly to Foley et al.'s (1995) separa­
tion of concerns; that is, users form a conceptual intention, reformulate it into
the semantics of several commands, construct the required syntax, and eventu­
ally produce the lexical token by the action of moving the mouse to select a point
on the screen. Norman makes a contribution by placing his stages in the context
of et;cles of action and evaluation, which take place over seconds and minutes.
This dynamic process of action distinguishes Norman's approach from the other
theories, which deal mainly with knowledge that must be in the user's mind.
Furthermore, the seven stages of action lead naturally to identification of the
gulf of execution (the mismatch between the user's intentions and. the all.owable
actions) and the gulf of evaluation (the mismatch between the system's represen­
tation and the user's expectations).

This theory leads Norman to suggest four principles of good design:

1. The state and the action alternatives should be visible.

2. There should be a good conceptual model with a consistent system image.

3. The interface should include good mappings that reveal the relationships
between stages.

4. Users should receive continuous feedback.

Norman places a hea, ,y emphasis on studying errors, describing how errors
often occur in moving from goals to intentions to actions and to exect1tions.

The stages-of-action theory helps designers to describe user exploration of an
interface (Polson and Lewis, 1990). As users try to accomplisl1 their goals, there
are four critical points where user failures can occur: (1) users may form inade­
quate goals, (2) users might not find the correct interface object because of an
incomprehensible label or icon, (3) users may not know how to specify or execute
a desired action, and (4) users may receive inappropriate or misleading feedback.

Refinements of the stages-of-action theory have been developed for other
domains. For example, information seeking has been characterized by these
stages: (1) recognize, (2) accept the information problem, (3) formulate and
(4) express the query, then (5) examine the results, (6) reformulate the problem,
and (7) use the results (Marchionini and White, 2007). Of course, there are varia­
tions with users skipping stages or going back to earlier stages, but the model
helps guide designers and users.

Commercial website designers know the benefit of a clear stages-of-action
theory in guiding anxious users through a complex process. For example, the
Amazon.com website converts the potentially confusing checkout process into a

110 Chapter 3 Guidelines, Principles, and Theories

comprehensible four -stage process: (1) Sign-in, (2) Shipping & Payment,
(3) Gift-Wrap, and (4) Place Order. Users can simply move through these four
stages or back up to previous stages to make changes. Amazon.com also recog­
nizes the 11eed for a frequent user shortcut, the I-click purchase, for products
such as a Kindle book.

Designers can apply the stages-of-action theory by thinking deeply about the
beginning, middle, and end stages to ensure that they cover a wide enough
scope of usage. Many new products emerge as a result of adding novel features
to what was considered a well-defined process; for examp le, expanding the
music-playing process to include the earlier stages of music purchase or compo­
sition and the later stages of music sharing or reviewing/rating.

3.4.3 Consistency theories
An important goal for designers is a consistent user interface. The argument for
cons istency is that if terminology for objects and actions is orderly and describ­
able by a few rules, users will be ab le to learn and retain them easily. This exam­
ple illustrates consistency and two kinds of inconsistency (A illustrates lack of
consistency, and B shows consistency except for a single violation):

Consistent Inconsistent A Inconsistent B

delete/ insert table delete I insert table de lete/ insert table

delete/ insert column remove/ add column remove/insert column

delete/ insert row destro y/ create row delete/insert row

delete/ insert border erase/ draw border delete/insert border

Each of the actions in the consistent version is the same, whereas the actions
vary for inconsisten t versio n A. The inconsistent action verbs are all accep table,
but their var iety suggests that they will take longer to learn , will cause more
errors, wi ll slow down users , and will be harder for users to remember.
Inconsistent version B is somehow more startling, because there is a single
unpredictable inconsistency; it stands out so dramatically that this language is
likely to be remembered for its peculiar inconsistency.

Consistency for objects and actions (nouns and verbs) is a good starting point,
but there are many other forms of consistency that require careful thought by
designers. Consistent use of color, layout, icons, fonts, font sizes, button sizes,
and much more is v ital in giving users a clear understanding of tl1e interface.
Inconsistency in elements such as the positioning of buttons or colors will slow
users down by 5-10 %, while changes to terminology slow users by 20-25 %.

Consistency is an important goal, but there may be conflicting forms of consis­
tency, and sometimes inconsistency is a virtue (for example, to draw attention to
a dangerous action). Competing forms of consistency require designers to make
difficult choices or invent new strategies. For example, while automobi le

3.4 Theories 111

interface designers have agreed to always place the accelera tor pedal to the right
of the brake pedal, there's no agreement about whether turn signal controls
should be to the right or left of the steering wheel.

Consistency issues are critical in the design of mobile devices. In successful
products, users get accustomed to consistent patterns, such as initiating actions
with a left-side button while terminating actions with a right-side button. Simi­
larly, up and down scrolling actions should be done consistently using buttons
tha t are vertically aligned. A frequent problem is the inconsistent placement of
the Q and Z characters on phone buttons.

Designers can enforce consistency by developing detailed guidelines docu ­
ments for their designs (Section 4.3) that spell out all of the consistency require­
ments. Exper t reviewers of user it1terfaces can then verify the consistency of the
design. This requires a careful eye and thoughtful attention to how each screen
is laid out, each action sequence is carried out, and each sound is played.

3.4.4 Contextual theories

The design -by-levels, stages-of -action, and consistency theories address the spe­
cifics of how objects and actions appear on displays and what actions users take
to carry out their tasks. These theories and design aspects might be called
micro-HCI, since they cover measurable performance in terms of speed and
errors. Micro -HCI is best studied with the scientific methods of experimental
and cognitive psychology using 30- to 120-mmute controlled experiments and
statistical tests for significant differences between groups workmg on well­
defined tasks

Micro-HC I has been and continues to be a great success story, but there is a
growmg awareness that tightly controlled laboratory studies of isolated phe­
nomena are only one part of the story. The rise of nuzcro-HCI, which emphasi zes
the user experience, the usage context, and social engagement, has opened up
new possibilities for researchers and practitioners. While micro-HC I research is
more about laboratory studies to collect clear performance measures for identi­
fiable tasks (e.g., how many seconds to fmd the last flight on July 4 from
Washington, DC, to London), macro -HCI research is more about ethnographic
observation of users doing work or play in their familiar context over days or
even months. The outcomes of micro-HCI research are statistically significant
differences that support or refute a hypothesis, while the outcomes of macro­
HCI research are insights about what leads to increased user satisfaction, how
the context of use ma tters, and how new applications could improve education,
health, safety, or the environment.

Macro-HCI thinking leads to different kmds of theories that might best be
called contextual, since they co11sider the emotional, physical, and social con­
texts of use. Happy users will persevere in the face of frustrations, cope with
mterruptions from neighbors, and ask for help when they need it. In short, tl1e

112 Chapter 3 Guidelines, Principles, and Theories

BOX 3.5
Theory types that organize evaluation of user interfaces and guide design .

Micro -HCI Theories Focus on measurable performance (such as speed
and errors) on multiple standard tasks taking seconds
or minutes in laboratory environments

• Design-by-levels Start with high-level design and move to smaller
objects and actions

• Stages-of-action Consider user behavior as they form intentions and
seek to realize their goals.

• Consistency Strive for consistency in objects and actions, shown
by words, icons, co lors, shapes, gestures, menu
choices

Macro -HCI Theories Focus on case studies of user experience over weeks
and months in realistic usage contexts with rich social
engagement

• Contextual Support users who are embedded in emotional,
physica l, and social environments

• Dynamic Design for evo luti on of user behavior as users move
through leve ls of mastery, performance, and leadership

physical and social env ironments are inextricably intertwined with use of
information and communications technologies. Design cannot be separated
from patterns of use.

Suchman's (1987) analysis in her book Plans and Situated Action is often cred ­
ited with launching this reconsideration of human-computer interaction. She
argued that the cognitive model of orderly human plans that were executed
when needed was insufficient to describe the richer and livelier wor ld of work or
personal usage. She proposed that users' actions were situated in time and place,
making user behavior highly responsive to other people and to environmental
contingencies. If users got stuck in using an interface, they might ask for help,
depending on who was around, or consu lt a manual, if one were avai lable. If
they were pressed for time, they might risk some shortcuts, but if the work was
life-critical, they wou ld be extra cautious. Rather than having fixed plans, users
cons tantl y changed their plans in respo11se to tl1e circumstances. The argument
of distributed cognition is that knowledge is not only in the users' minds but
distributed in their environments-knowledge is stored on paper documents,
accessible from electronic files, or available from colleagues.

Co11textual theories also address the shif t from use of a computer to interac­
tion wi th a device-rich environment filled with sensors, responsive appliances,
display walls, and audio generators. Rather than picking up a device, users

3.4 Theories 113

activate automatic doors, hand dryers, or ligh t switches. Sometimes users are
inside a device such as an automobile, forcing designers to consider the sur­
rounding space and the other people in the car as well as the sounds, vibrations,
and forces of acceleration. Contextual theories often emphasize the social envi­
ronment in which users are engaged with other people who can provide assis­
tance or can be distractions.

Advocates of contextual theories believe that the turbulence of actual usage
(as opposed to idealized task specifications) means that users have to be more
than test subjects – they have to be participants in design processes. Proponents
of contextual theories encourage more ethnographic observation, longitudinal
case studies, and action research by participant observers (Boellstorff et al., 2012;
Crabtree et al., 2012; Horst and Miller, 2013).

Breakdowns are often seen as sources of insight about design, and users are
encouraged to become reflective practitioners who are continuously engaged in
the process of design refinement. Understanding the transition from novice to
expert and the differences in skill levels has become a focus of attention, further
calling into question the utility of hour-101,g laboratory or half-day usability-test­
ing studies as a guide to the behavior of users after a month or more of experience.

Contextual theories are especially relevant to mobile devices and ubiquitous
computing innovations. Such devices are portab le or installed in a phys ical space,
and they are often designed specifically to provide place-specific information
(for example, a city gu ide on a portable computer or a museum guide that gives
information on a nearby painting). Location information by way of GPS systems
enables new services but raises concerns about misuse of tracking information.

Designers can apply contextual theories by observing t1sers in their own
environments as they carry out their work, engage socia lly, or participate in
sports or play. A detailed record of how tasks are chosen and carried out,
including collaborations with others, internal or external interruptions, and
errors that occur, would lay the basis for interface design. Contextua l theories
are about how people form inten tions, how aspirations crystalize, how empa­
thy is encouraged, and how trust shapes behavior; they are also about
emotional states of excitement or frustration, the joy of attaining goals, and the
disappointment of failure. These strong reactions are hard to capture in predic­
tive mathematical equations, but it is important to study and understand them.
To that end, many researchers are shifting their me thods from controlled
experiments to ethnographic observation, focus group discussions, and long­
term case studies. Surveys and interviews can provide quantitative data for
much-needed theories of how design variab les affect users' levels of satisfac­
tion, fear, trust, and cooperativeness.

While contextual theories emphasize the changes to observation and research,
contextual theories can also guide design. If interruptions are an impediment,
then users might be given the option of blocking them. If usage outdoors is a
requirement, then contrast setting or font sizes should be easily adjus tab le. If

114 Chapter 3 Guidelines, Principles, and Theories

collaboration with others is a high priority, then easy sharing of screens or tex­
ting should be possib le.

A taxonomy of mobile device applications could guide innovators:

• Monitor blood pressure, stock prices, or air quality and give alerts when
normal ranges are exceeded.

• Gather information from meeting attendees or rescue team members and
spread the action list or current status to all.

• Participate in a large group activity by voting and relate to specific individuals
by sending private messages.

• Locate the nearest restaurant or wa terfall and identify the details of the current
location.

• Capture information or photos left by others and shn.re yours with future visitors.

These five pairs of actions could be tied to a variety of objects (such as photos,
annotations, or documents), suggesting new mobile devices and services . They
also suggest that one way of thinking about user interfac es is by way of the
objects that users encounter and the actions that they take (Robinson et al., 2015).
A more ambitious use of mobile devices is to aggregate information from thou­
sands of cellphones to determine where there is highway congestion or which
rides at an amusement park have the longest waiting lines.

3.4.4 Dynamic theories
A key aspect of macro-HCI is how users evolve over weeks and months, espe­
cially as they move from novices to experts, from new customers to frequent
buyers, or from readers of Wikipedia to active collaborators or administrators.
These theories address design for evolutionary development of skills mastery,
behavior change, reputation growth, and leadership capacities.

Dynamic theories owe much to the theories of adoption or innovation diffu­
sion (Rogers, 2003), which include five attributes:

1. relative advantage: faster, safer, more error free usage, or cheaper

2. compatibility: fitting for users' need, consistent with existing values

3. trial-ability: availability to experimen t with innovation

4. observabili ty: visibili ty of innovation to others

5. less complexity: ease of learning and use

These attributes lead to macro-HCI design guidelines, such as suggesting
specific user-interface features, combining features to make some more visible
than others, and providing informative feedback to users about their usage his­
tory. Other macro-HCI design guidelines will suggest ways of training users
about features (informing tllem about new features), rewarding them for suc­
cesses (showing their progress in reading a book or their score in a game), and

3.4 Theories 115

sharing their progress with others (notifying friends about an exercise achieve­
ment or business associates about a price change).

Dynamic theories deal with long-term (weeks or months) changes in behav­
ior for health (smoking cessation, diet, exercise, or performance in memory
games) or education (completing an online course or demonstrating increased
familiarity with a body of knowledge). A large category of dynamic theories
cover customer loyalty plans that encourage increased commitment, such as
awards from restaurants, airlines, or hotels. These carefully designed programs
have multiple award levels, such as bronze, silver, gold, and platinum, with
carefully chosen benefits to encourage increased activity.

Behavior change by badge awards and loyalty programs will become increas­
ingly important because of the growing data sources about what works and
wI-1at doesn't. The remarkably focused and personalized ways of persuading
users and raising motivation will dramatically increase the possibilities for
designers who understand whe11 personal recognition, social rewards, commu­
nity awareness, and financial compensation are most effective.

Dynamic theories are strong among designers of onliI1e communities and
user-generated content sites. They know that users often move through stages
as they gain confidence and a greater sense of responsibility for quality. There
are many paths, but a study of Wikipedia contributors (Bryant et al., 2005) sug­
gests at least these stages: (1) reader of articles related to personal interests,
(2) fixer of mistakes and omissions in familiar topics, (3) registered user and
caretaker for a collection of articles, (4) author for new articles, (5) participant in
community of authors, and (6) administrator who is active in governance and
fuh1re directions.

Following these results, the Reader-to-Leader Model described how to design
user-interface and social engagement features to promote movement through
these stages over a period of weeks or months (Preece and Shneiderman, 2009).
At early stages, there are user-mterface design guidelines, such as highlighting
key features and valuable content, and social engagement design guidelines,
such as encouragement from friends, family, and respected authorities. At later
stages, there are user-mterface design guidelines, such as visible recognition for
contributions, and social engagement design guidelines, such as promoting
empathy, supporting mentoring, raising trust, and facilitating conflict resolution.

Macro-HCI theories also promote the idea that user interfaces have profound
societal effects with positive outcomes such as increased social communication,
safety, or health awareness and negative outcomes such as undermining concen­
tration, invading privacy, or exposing users to hackers. Visionaries see user inter­
faces as shaping personal processes of mindfulness, reflection, or empathy and
community processes of civic participation, democratic sharing, or conflict reso­
lution (Bell and Dourish, 2011; Nelson and Stolterman, 2012; Calvo and Peters,
2014). At a grander scale, macro-HCI dreamers believe that better user interfaces
and user experiences can support international development, improved health­
care, environmental preservation, and peaceful dispute reconciliation.

116 Chapter 3 Guidelines, Principles, and Theories

Practitioner's Summary

Design principles and guidel ines are emerging from practical experi­
ence and empirical studies. Managers can benefit by reviewing available
guidelines documents and then constructing local versions. These docu­
ments record organizational policies, support cons istency, and record the
results of practical and experimental testing. Guidelines documents also
stimu late discussion of user-interface issues and help train new design­
ers. More established principles-such as recognizing user diversity, striv­
ing for consistency, and preventing errors – have become widely accepted,
but the y require fresh interpretation as technolog y and applications evolve.
Automation is increasing for many tasks, but preserving human control is
still a beneficial goal.

Micro-HCI and macro-HCI theories are being validated and refined to clarify
the desigi1 implications. For expert users with established sequences of actions,
predictive models that guide designers to reduce the time required for each step
are valuable. For novel applications and novice users, clarifying task objects and
actions (for example, songs and albums that can be played or added to play lists)
and promoting consis ten cy can lead to easily learned designs that promote user
confidence. For every design, extensive testing and iterative refinement are nec­
essary parts of the development process.

Researcher's Agenda

The central problem for human-computer-interaction researchers is develop­
ing adequate micro-HCI and macro-HCI theories. Traditional psychological
the ories must be extended and refined to accommodate the complex human
learnin g, memory, and problem solving required in user interfaces and user
experiences. Useful goals include descriptive taxonomies, explanatory theories,
and predictive models. When predictions can be made for learning times, per­
formance speeds, error rates, subjective satisfaction, or human retention over
time, designers can more easily choose among competing designs.

Theories in human-computer interaction can be grouped into five families:
those that focus on design by levels, stages of action, consistency, con textual
awareness, and evolutionary dynamics. Theories can be useful even if they are
narrowly focused on a specific task, such as choosing a video from a database of
millions of videos . Even more powerful are theories that apply to diverse tasks
such as web searching, on line reviewing, or encour aging comm unjt y participa­
tion. Applied research problems are suggested by each of the hundreds of design

Discussion Questions 117

principles or guidelines that have been proposed. Each validation of these prin­
ciples and clarification of the breadth of applicability is a small but useful contri­
bution to the emerging mosaic of human performance with interactive systems.

WORLD WIDE WEB RESOURCES

www. pearsonglobaleditions.com / shneiderman

Many websites include guidelines documents for desktop, web, and mobile
device interfaces and recommendations for universal usability strategies to
accommodate users with disabilities or other special needs. Theories are pro­

liferating, and the web is a good place to keep up with the latest ones from
major developers and sources promoting universal usability:

• Apple Human Interface Guidelines: http://developer.app le.com
• Microsoft Windows User Experience Interaction Guidelines:

https://msdn.microsoft.com

• World Wide Web Consort ium (W3C) guide lines:
http://www.w3.org/TR/WCAG20/

• Interaction Design Foundation Encyclopedia covers theories:
https://www. i nteractio n-desig n.org/

Debates over hot topics can be found in relevant biogs and newsgroups,

which are searchable from many standard services such as Goog le or Bing.

Discussion Questions

1. Give a brief explanation of the Eight Golden Rules of Interface Design. State
an example you have seen on a device, computer interface, or web site that
,riolates tho se rules.

2. Don Norman sugges ts organizing screens and menus functionally, design­
i11g commands and menu choices to be distinctive, and making it difficult
for users to take irreversible actions. Norman also says to provide feedback
about the state of the interface (e.g., changing the cursor to show whether a
map inter face is in zoom- in or select mod e) and designing for cons istency of
actions (e.g., ensuring that Yes/No buttons are always displayed in the same
order). State one example you have seen where you know these rules have
been vio lated . Although this is crucial to a user interface's success, suggest
why there may be challenges to implement some of Norman's guidelines.

3. Clarify the difference among guidelines, principles, and theories.

118 Chapter 3 Guidelines, Principles, and Theories

4. What are some of the techniques that can be used to get the user's attention?
Why is it important to exercise caution when using these techniques?

5. What are the stages of forming explanatory theories as suggested by Don
Norman?

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