Posted: September 16th, 2022

human growth

  

Physical Growth:

The Rapid Advances of Infancy

Infants grow at a rapid pace over the first two years of their lives (see Figure 4-1)

5 months: average birthweight doubles to around 15 pounds

1 year: weight triples to about 22 pounds

End of 2nd year: average child weighs around four times as much as he or she did at birth

Physical Growth:

The Rapid Advances of Infancy

Not all parts of an infant’s body grow at the same rate

Birth: head accounts for one-quarter of the newborn’s entire body size

During 1st and 2nd year: rest of the body begins to catch up

Physical Growth:

The Rapid Advances of Infancy

Can you give an example of each principle?

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Define:

Cephalocaudal principle states that growth follows a direction and pattern that begins with the head and upper body parts and then proceeds to the rest of the body.

Proximodistal principle states that development proceeds from the center of the body outward. See Table 4.1.

Principle of hierarchical integration states that simple skills typically develop separately and independently. Later these simple skills are integrated into more complex ones.

Principle of the independence of systems, which suggests that different body systems grow at different rates.

Birth: around 7 pounds; 20 inches

5 months: doubled birth weight

12 months: tripled birth weight; 30 inches

2nd year: slows; 4x birth weight; 36 inches

Nervous System and Brain:

The Foundations of Development

Neurons are the basic cells of the nervous system

Nervous system comprises the brain and the nerves that extend throughout the body

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How great brains grow!
Birth

100-200 billion neurons

Relatively few neurons-neuron connections

During first two years

Billions of new connections established and become more complex

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Birth: Neurons multiply at an amazing rate prior to birth. At some points in prenatal development, cell division creates some 250,000 additional neurons every minute.

By year 2: The intricacy of neural connections continues to increase throughout life. In fact, in adulthood a single neuron is likely to have a minimum of 5,000 connections to other neurons or other body parts.

Use it or lose it!
Babies are actually born with many more neurons than they need

Although synapses are formed throughout life, based on our changing experiences, the billions of new synapses infants form during the first two years are more numerous than necessary

Synaptic pruning

Unused neurons are eliminated

Allows established neurons to build more elaborate communication networks with other neurons

Development of nervous system proceeds most effectively through loss of cells

Myelin

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Synaptic pruning: elimination of unused neurons that allows established neurons to build more elaborate communication networks with other neurons. Unlike most other aspects of growth, then, the development of the nervous system proceeds most effectively through the loss of cells.

Neurons that do not become interconnected with other neurons as the infant’s experience of the world increases become unnecessary.

They eventually die out, increasing the efficiency of the nervous system.

Myelin: Axons of neurons become coated with myelin, a fatty substance that, like the insulation on an electric wire, provides protection and speeds the transmission of nerve impulses.

Contributes to increased weight of brain

Even though many neurons are lost, the increasing size and complexity of the remaining ones contribute to impressive brain growth.

A baby’s brain triples its weight during his or her first 2 years of life, and it reaches more than three-quarters of its adult weight and size by the age of 2.

Coming to terms with your brain…

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Like all cells in the body, neurons have a cell body containing a nucleus.

But unlike other cells, neurons have a distinctive ability: They can communicate with other cells, using a cluster of fibers called dendrites at one end.

Dendrites receive messages from other cells.

At their opposite end, neurons have a long extension called an axon, the part of the neuron that carries messages destined for other neurons.

Neurons do not actually touch one another. Rather, they communicate with other neurons by means of chemical messengers, neurotransmitters, that travel across the small gaps, known as synapses, between neurons.

Form and Function: Brain Growth

Neurons reposition themselves with growth, becoming arranged by function

Cerebral cortex

Subcortical levels

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Some move into the cerebral cortex, the upper layer of the brain, while others move to subcortical levels, which are below the cerebral cortex.

As time passes, however, the cells in the cerebral cortex, which are responsible for higher-order processes such as thinking and reasoning, become more developed and interconnected.

The subcortical levels, which regulate such fundamental activities as breathing and heart rate, are the most fully developed at birth.

Don’t shake the baby!
Shaken Baby Syndrome

Brain sensitive to form forms of injury

Shaking can lead to brain rotation within skull

Blood vessels tear  severe medical problems, long-term disabilities, and sometimes death

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Brain Development: Influences and Definitions

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Define:

Plasticity: the degree to which a developing structure or behavior is modifiable due to experience

Sensitive period is a specific, but limited, time, usually early in an organism’s life, during which the organism is particularly susceptible to environmental influences relating to some particular facet of development.

What do babies do all day?
Integrating the bodily systems: Life cycles of infancy

Rhythms: repetitive, cyclical patterns of behavior

Wake

Sleep

Eat

Eliminate

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These most basic activities are controlled by a variety of bodily systems.

Although each of these individual behavioral patterns probably is functioning quite effectively, it takes some time and effort for infants to integrate the separate behaviors. In fact, one of the neonate’s major missions is to make its individual behaviors work in harmony, helping it, for example, to sleep through the night.

Rhythms and States
State

One of major body rhythms

Degree of awareness infant displays to both internal and external stimulation

Change in state alters amount of stimulation required to get infant’s attention

Electrical brain waves can be measured by electrocephalogram (EEG)

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Some of the different states that infants experience produce changes in electrical activity in the brain.

These changes are reflected in different patterns of electrical brain waves, which can be measured by a device called an electroencephalogram, or EEG.

Starting at three months before birth, these brain wave patterns are relatively irregular.

By the time an infant reaches the age of 3 months, a more mature pattern emerges and the brain waves become more regular.

Primary Behavioral States

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Primary Behavioral States

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Sleep: Perchance to Dream
Major state

16-17 hours daily (average); wide variations

Different than adult sleep

2 hour spurts; periods of wakefulness

Cyclic pattern

By 16 weeks sleep about 6 continuous hours; by 1 year sleep through night

(See Table 4-2)

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By 1 year need about 15 hours sleep

Cyclic pattern: During periods of sleep, infants’ heart rates increase and become irregular, their blood pressure rises, and they begin to breathe more rapidly

A Quick Review of Behavioral States

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REM Sleep

Period of active sleep

Closed eyes begin to move in a back-and-forth pattern

Takes up around one-half of infant sleep

May provide means for brain to stimulate itself through autostimulation

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Sometimes, although not always, their closed eyes begin to move in a back-and-forth pattern, as if they were viewing an action-packed scene. This period of active sleep is similar, although not identical, to the rapid eye movement, or REM, sleep, that is found in older children and adults and is associated with dreaming.

At first, this active, REM-like sleep takes up around one-half of an infant’s sleep, compared with just 20 percent of an adult’s sleep (see Figure 4-6). However, the quantity of active sleep quickly declines, and by the age of 6 months, amounts to just one-third of total sleep time.

Some researchers think it provides a means for the brain to stimulate itself—a process called autostimulation.

Stimulation of the nervous system would be particularly important in infants, who spend so much time sleeping and relatively little in alert states.

SIDS: The Unanticipated Killer

Sudden infant death syndrome (SIDS) is a disorder in which seemingly healthy infants die in their sleep

SIDS strikes about 2,500 infants in the United States each year

Although it seems to occur when the normal patterns of breathing during sleep are interrupted, scientists have been unable to discover why that might happen

SIDS

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Sudden infant death syndrome (SIDS) is a disorder in which seemingly healthy infants die in their sleep

SIDS strikes about 1 in 1,000 infants in the United States each year.

Although it seems to occur when the normal patterns of breathing during sleep are interrupted, scientists have been unable to discover why that might happen.

American Academy of Pediatrics now suggests that babies sleep on their backs rather than on their sides or stomachs—called the back-to-sleep guideline. In addition, they suggest that parents consider giving their babies a pacifier during naps and bedtime.

SIDS is found in children of every race and socioeconomic group and in children who have had no apparent health problems

Back-to-sleep is important!

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Review and Apply

cephalocaudal; proximodistal; heirarchial integration; independence

nervous

neurons; connections

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Review and Apply

Brain plasticity

sensitive; susceptible

rhythms

internal; external

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Review and Apply

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Motor Development

Shape and proportions of newborn babies are simply not conducive to easy mobility

Young infants lack the strength to raise large heads

Movement is further impeded because limbs are short in relation to the rest of the body

Infant bodies are mainly fat, with a limited amount of muscle; the result is a lack strength

Motor Development
BUT

At birth newborns have an extensive repertoire of behavioral possibilities brought about by innate reflexes, and their range of motor skills grows rapidly during the first two years of life

Reflexes: Inborn Physical Skills
Reflexes

Learned, organized involuntary responses that occur automatically in presence of certain stimuli

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Some Basic Reflexes in Infants

Some Basic Reflexes in Infants

Ethnic and Cultural Differences and Similarities in Reflexes
Reflexes

Genetically determined

Universal

Cultural variations in ways displayed

Moro reflex

Serves

Diagnostic tool

Social function

Survival function

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Moro Reflex: Some differences reflect cultural and ethnic variations.

Caucasian infants show a pronounced response to situations that produce the Moro reflex. Not only do they fling out their arms, but they also cry and respond in a generally agitated manner.

Navajo babies react to the same situation much more calmly. Their arms do not flail out as much, and they cry only rarely.

Diagnostic tools for pediatricians. Because reflexes emerge and disappear on a regular timetable, their absence—or presence—at a given point of infancy can provide a clue that something may be amiss in an infant’s development.

Milestones of Motor Development

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Fifty percent of children are able to perform each skill at the month indicated in the figure.

However, the specific timing at which each skill appears varies widely.

For example, one-quarter of children are able to walk well at 11.1 months; by 14.9 months, 90 percent of children are walking well. Is knowledge of such average benchmarks helpful or harmful to parents? (Source: Adapted from Frankenburg et al., 1992.)

Young infants still are able to accomplish some kinds of movement.

When placed on their stomachs they wiggle their arms and legs and may try to lift their heavy heads.

As their strength increases, they are able to push hard enough against the surface on which they are resting to propel their bodies in different directions.

They often end up moving backwards rather than forwards, but by the age of 6 months they become rather accomplished at moving themselves in particular directions.

These initial efforts are the forerunners of crawling, in which babies coordinate the motions of their arms and legs and propel themselves forward.

Crawling appears typically between 8 and 10 months.

Walking comes around the age of 9 months; most infants are able to walk by supporting themselves on furniture, and half of all infants can walk well by the end of their first year of life.

Most are able to sit without support by the age of 6 months.

Dynamic Systems
Dynamic systems theory

Describes how motor behaviors are assembled

Motor skills do not develop in vacuum

Each skill advances in context of other motor abilities

As motor skills develop, so do non-motoric skills

Theory places emphasis on child’s own motivation (a cognitive state) in advancing important aspects of motor development

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Motor development in a particular sphere, such as beginning to crawl, is not just dependent on the brain initiating a “crawling program” that permits the muscles to propel the baby forward.

Instead, crawling requires the coordination of muscles, perception, cognition, and motivation.

Theory emphasizes how children’s exploratory activities, which produce new challenges as they interact with their environment, lead them to advancements in motor skills.

Developmental Norms
Comparing Individual to Group Norms:

Represent the average performance of a large sample of children of a given age

Permit comparisons between a particular child’s performance on a particular behavior and the average performance of the children in the norm sample

Must be interpreted with caution

Brazelton Neonatal Behavior Assessment Scale (NBAS)

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Brazelton Neonatal Behavior Assessment Scale (NBAS): one of the most widely used techniques to determine infants’ normative standing; measure designed to determine infants’ neurological and behavioral responses to their environment; provides a supplement to the traditional Apgar test.

Developmental Diversity

Cultural Dimensions of Motor Development

Using information from your text, answer the following:

Does earlier emergence of a basic motor behavior in a given culture has lasting consequences for specific motor skills and for achievements in other domains?

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Guide students to appropriate section in the text.

Divide into small groups. Assign students by Ache, Kipsigis, and Western babies. Ask students to reply to the question based on their specific group.

Concluding comment: cultural factors help determine the time at which specific motor skills appear. Activities that are an intrinsic part of a culture are more apt to be purposely taught to infants in that culture, leading to the potential of their earlier emergence.

Nutrition in Infancy
Fueling Motor Development

Without proper nutrition, infants cannot reach physical potential and may suffer cognitive and social consequences

Infants differ in growth rates, body composition, metabolism, and activity levels

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Rapid physical growth that occurs during infancy is fueled by the nutrients that infants receive. Without proper nutrition, infants cannot reach their physical potential, and they may suffer cognitive and social consequences.

So what is a healthy caloric allotment for infants?

About 50 calories per day for each pound of weight

Most infants regulate their caloric intake quite effectively on their own

If are allowed consume as much they seem to want, and not pressured to eat more, they will be healthy

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Malnutrition
Malnutrition

Condition of having improper amount and balance of nutrients, produces several results, none good

More common in children living in many developing countries

Slower growth rate

Chronically malnourished during infancy = later lower IQ score

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Malnutrition, the condition of having an improper amount and balance of nutrients, produces several results, none good.

More common among children living in many developing countries

Slower growth rate apparent by the age 6 months

By 2 years, height and weight are only 95 percent the height and weight of children in more industrialized countries.

Chronically malnourished during infancy later score lower on IQ tests and tend to do less well in school. These effects may linger even after diet has improved substantially.

Undernutrition: Dietary Deficiencies

Undernutrition also has long-term costs, including mild to moderate cognitive delays

Up to 25% of 1- to 5-year-old US children have diets that fall below minimum caloric intake recommended by nutritional experts

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When Malnutrition Is Severe
Maramus

Malnutrition during first year

Infants stop growing.

Attributable to severe deficiency in proteins and calories

Causes the body to waste away and ultimately results in death

Kwashiorkor

Found in older children

Child’s stomach, limbs, and face swell

Body struggles to make use of few available nutrients

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Malnutrition during the first year can produce marasmus, a disease in which infants stop growing. Marasmus, attributable to a severe deficiency in proteins and calories, causes the body to waste away and ultimately results in death. Older children are susceptible to kwashiorkor, a disease in which a child’s stomach, limbs, and face swell with water.

Nonorganic Failure to Thrive

Sufficient nutrition

Symptoms

Reversal

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Infants receive sufficient nutrition but are deprived of attention and stimulation.

Symptoms include underdevelopment, listlessness, and apathy and usually occurs by age 18 months.

Reversal possible through intensive parent training or removal to emotionally supportive environment.

So What Is the Answer?
Breast milk

Offers all nutrients infant needs for first 12 months of life

Is more easily digested than alternative

Provides some immunity to variety of childhood diseases

May enhance cognitive growth

Offers significant emotional advances for mother and child

Not cure-all for infant nutrition and health

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Introducing Solid Foods: When and What?

Solids can be started at 6 months but are not needed until 9 to 12 months (AAFP)

Introduced gradually, one at a time

Cerealstrained fruits

Time of weaning varies greatly in developed and developing countries

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Review and Apply

universal; genetically

physical; consistent; cultural

timing; motor

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Review and Apply

physical

Malnutrition; growth; intellectual

nutritional; immunological; emotional; physical; mother

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Review and Apply

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The Development of the Senses
If all the lights in this room went out RIGHT NOW, what would your senses tell you (sensation)?

What do you think about being in the dark with your class (perception) or about an instructor who was crazy enough to go to blackout to teach a concept (fill in this part yourself)?

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Visual Perception: Seeing the World

Newborn’s distance vision ranges from 20/200 to 20/600

By 6 months, average infant’s vision is already 20/20

Other visual abilities grow rapidly

Binocular vision

Depth perception

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Infant can only see with accuracy visual material up to 20 feet that an adult with normal vision is able to see with similar accuracy from a distance of between 200 and 600 feet.; distance vision is 1/10th to 1/3rd that of average adult’s.

Infant Visual Preference
Preferences that are present from birth

Genetically preprogrammed to prefer particular kinds of stimuli

Prefer to look at patterned over simpler stimuli

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Figure 4-12 Preferring Complexity
In a classic experiment, researcher Robert Fantz found that two- and three-month-old infants preferred to look at more complex
stimuli than simple ones. (Source: Adapted from Fantz, 1961.)

They prefer curved over straight lines, three-dimensional figures to two-dimensional ones, and human faces to non-faces. Such capabilities may be a reflection of the existence of highly specialized cells in the brain that react to stimuli of a particular pattern, orientation, shape, and direction of movement.

Prefer their own mother’s face to other faces; distinguish between male and female faces

Direct students to Figure 4.14.

Ask: How would you use this information to explain how heredity and environmental experiences are integrated to determine infant capabilities?

Facing the World
Genetics is not the sole determinant of infant visual preferences

A few hours after birth, infants have already learned to prefer their own mother’s face to other faces

Similarly, between the ages of six and nine months, infants become more adept at distinguishing

between the faces of humans, while they become less able to distinguish faces of members of other species

They also distinguish between male and female faces

Auditory Perception: The World of Sound
Infants

Hear before birth and have good auditory perception after they are born

Are more sensitive to certain frequencies

Reach adult accuracy in sound localization by age 1

Can discriminate groups of different sounds

React to changes in musical key and rhythm

Can discriminate many language related sounds

Are born with preferences for particular sound combinations which may be shaped by prenatal exposure to mothers’ voices

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Smell and Taste in a Small World
Smell

Well developed at birth

Helps in recognition of mother early in life

Used to distinguish mother’s scent (only in breast fed babies); cannot distinguish father on basis of odor

Taste

Have innate sweet tooth

Show facial disgust at bitter taste

Develop preferences based on what mother ate during pregnancy

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Ouch!
Contemporary Views on Infant Pain

Today, it is widely acknowledged that infants are born with the capacity to experience pain

Developmental progression in reaction to pain

Infants born with capacity to experience pain; produces distress

Exposure to pain in infancy may lead to permanent rewiring of nervous system resulting in greater sensitivity to pain during adulthood

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The Power of Touch

Touch is one of most highly developed sensory systems in a newborn

Even youngest infants respond to gentle touches

Several of the basic reflexes present at birth require touch sensitivity to operate

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Several theorists have suggested that one of the ways children gain information about the world is through touching.

Multimodal Perception: Combining Individual Sensory Inputs
New area of study in infant research

Some researchers argue that sensations are initially integrated with one another in the infant

Others maintain that infant’s sensory systems are initially separate and that brain development leads to increasing integration

It does appear that by an early age infants are able to relate what they have learned about an object through one sensory channel to what they have learned about it through another

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Multimodal approach to perception considers how information that is collected by various individual sensory systems is integrated and coordinated.

Infants’ multimodal perception abilities showcase the sophisticated perceptual abilities of infants, which continue to grow throughout the period of infancy. Such perceptual growth is aided by infants’ discovery of affordances , the options that a given situation or stimulus provides.

What are affordances?
Perceptible affordances

Exist where information on actions that are afforded are perceptible

These are dependent on language, culture, context, and experience and vary for different individuals

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Bring a small collection of found object to lecture. Have student work in groups to brainstorm about the affordances of the objects. Encourage rapid, spontaneous responses.

Ask students to equate this experience with that of an infant’s. What is different? What is the same?

Becoming an Informed Consumer of Development

Exercising Your Infant’s Body and Senses

Attempts to accelerate physical and sensory-perceptual development yield little success
but
infants need sufficient physical and sensory stimulation.

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How can this be accomplished?

Carry a baby in different ways

Let infants explore their environment

Engage in “rough-and-tumble” play

Let babies touch their food and even play with it

Provide toys that stimulate the senses, particularly toys that can stimulate more than one sense at a time

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Carry a baby in different positions—in a backpack, in a frontpack, or in a football hold with the infant’s head in the palm of your hand and its feet lying on your arm. This lets the infant view the world from several perspectives.

Let infants explore their environment. Don’t contain them too long in a barren environment. Let them crawl or wander around—after first making the environment “childproof” by removing dangerous objects.

Engage in “rough-and-tumble” play. Wrestling, dancing, and rolling around on the floor—if not violent—are activities that are fun and that stimulate older infants’ motor and sensory systems.

Let babies touch their food and even play with it. Infancy is too early to start teaching table manners.

Provide toys that stimulate the senses, particularly toys that can stimulate more than one sense at a time. For example, brightly colored, textured toys with movable parts are enjoyable and help sharpen infants’ senses.

Review and Apply

Sensation

Perception

well developed

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Review and Apply

Very early

pain

multiple senses

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Review and Apply

well prepared; perceptions

depth; motion; colors; sounds; smell

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Review and Apply

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EPILOGUE
Turn back for a moment to the prologue of this chapter, about a baby’s first steps, and answer these questions:

Which principles of growth (i.e., cephalocaudal, proximodistal, heirarchical integration, independence of systems) account(s) for the progression of physical activities that precedes Josh’s first steps?

What conclusions about Josh’s future physical development can be drawn based on the fact that his first steps occurred approximately two months early?

Can conclusions be drawn about his future cognitive development? Why?

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EPILOGUE

In walking at 10 months of age, Josh outpaced his little brother Jon by four months. Does this fact have any implications for the comparative physical or cognitive abilities of the two brothers? Why?

Do you think anything changed in the environment between the time Jon and Josh were born that might account for their different “first step” schedules? If you were researching this question, what environmental factors would you look for?

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EPILOGUE

Why were Josh’s parents so pleased and proud about his accomplishment, which is, after all, a routine and universal occurrence? What cultural factors exist in the U.S. culture that make the “first steps” milestones so significant?

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Physical development involves many stages: human body and nervous system, environmental impact, nutrition, and many others. After reading Chapter 4, provide your summary on the chapter accompanied with an opinion on development during infancy (what’s interesting to you?). make an essay with 5 paragraphs in APA format

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