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Infants, Children, and
Adolescents
Chapter 5
Physical
Development in
Infancy and
Toddlerhood
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Body Growth
 Gain 50% in height from birth to age
1; 75% by age 2
 Grow in spurts
 Gain “baby fat” until about 9 months,
then get slimmer
 Girls slightly shorter and lighter than
boys, some ethnic differences
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Growth Trends
Cephalocaudal
Proximodistal
 “Head to tail”
 Lower part of body
grows later than the
head
 “Near to far”
 Extremities grow
later than head,
chest, and trunk
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Growth
During
First Two
Years
Figure 5.1
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Epiphyses of the Bone
Figure 5.2
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The Skull at Birth
Figure 5.3
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Brain Development
 Human brain has 100 to
200 billion neurons that
store/transmit information
 At birth, brain closest to
adult size than any other
physical structure
 Neurons send messages
by releasing chemicals
called neurotransmitters.
Figure 5.4
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Major Milestones of
Brain Development
Figure 5.5
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Methods for Measuring
Brain Functioning
Table 5.1
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Functional Magnetic Resonance
Imaging (fMRI) and
Near Infrared Spectroscopy (NIRS)
Figure 5.7
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Regions
of the
Cerebral
Cortex
Figure 5.8
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Lateralization and Plasticity of
the Cerebral Cortex
Specialization of the left and right hemispheres of
the brain is called lateralization.

Left hemisphere: best at processing information in a
sequential, analytic way

Right hemisphere: best at processing information in a
holistic, integrative manner
In a highly plastic cerebral cortex, many areas are
not yet committed to one function; consequently,
the cortex has a high capacity for learning.
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Brain Plasticity Insights
 With injuries to the cerebral cortex occurring before birth
or in the first 6 months, language delays persisted to
about 3½ years of age.
 By age 5, the children caught up in grammatical and
vocabulary skills; the undamaged area of the brain—
either hemisphere—had taken over the language
function.
 Spatial skills showed more impairment after a brain
injury, likely because spatial processing is more
lateralized at birth.
 Brain plasticityCopyright
can© 2012
occur
later in adulthood (e.g., in
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stroke victims).
Sensitive Periods in
Brain Development
 Early, extreme sensory deprivation results
in permanent brain damage and loss of
function.
 Babies born with cataracts in both eyes who
have corrective surgery within 4 to 6
months show rapid improvement in vision.
 The longer the surgery is postponed, the
less complete the recovery of visual skills.
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Brain Development in
Orphanage Children
 Children adopted from
Romanian orphanages before
age 6 months showed dramatic
cognitive and physical gains.
 Those adopted after 6 months
showed serious intellectual
deficits.
 The chronic stress of early,
deprived orphanage rearing
disrupts the brain’s ability to
manage stress, with long-term
consequences.
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Figure 5.9
Appropriate Stimulation
Experience-expectant growth

Ordinary experiences
“expected” by brain to grow
normally

Occurs early and naturally
Experience-dependent growth
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
Specific experience, varies
widely across cultures

Rushing early learning can
overwhelm young brains.
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Sleep Patterns
 Sleep moves to an adult-like
night–day schedule during the
first year.
 Sleep needs decline from 18
to 12 hours a day by age 2.
 Night wakings often increase
between the ages of 1½ and 2
years, and then decline.
 Affected by brain development
and social environment
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Cultural Variations in Infant
Sleeping Arrangements
 Cosleeping is the norm for 90% of the
world’s population.
 Cultural values of collectivism versus
individualism strongly influence infant
sleeping arrangements.
 Cosleeping is increasing in the United
States, perhaps because more mothers
are breastfeeding.
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Influences on Early Growth
Heredity
Nutrition
 Breast v. bottle feeding
 Malnutrition
Emotional well-being
 Problems can cause
failure to thrive.
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Benefits of Breastfeeding
 Correct fat–protein balance
 Nutritionally complete
 Promotes healthy growth patterns
 Disease protection
 Better jaw and tooth development
 Ensures digestibility
 Easier transition to solid food
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Are Chubby Babies at Risk
for Later Obesity?
Recent research shows a relationship between
rapid weight gain in infancy and later
obesity.
What to do?

Breastfeed for six months.

Avoid foods loaded with sugar, salt, and
saturated fats.

Promote physical exercise.

Limit TV viewing time.
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Malnutrition
Types






Consequences 


Marasmus
Kwashiorkor
Iron-deficiency anemia
Food insecurity
Physical symptoms
Growth and weight problems
Poor motor development
Learning, attention problems
Passivity, irritability, anxiety
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Emotional Well-Being
Affection is as vital as food for healthy physical
growth.
Growth faltering applies to infants whose weight,
height, and head circumference are substantially
below age-related growth norms.

Infants are withdrawn and apathetic.

Often a result of disturbed parent–child relationship
Unhappy marriage or parental psychological
disturbance may be at fault.
May cause lasting cognitive and emotional difficulties


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The Steps of
Classical Conditioning
Figure 5.10
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Operant Conditioning Terms
Reinforcer
Punishment
Increases probability Reduces probability
of behavior
of behavior
occurring again
occurring again
 Presenting
 Presenting desirable
unpleasant stimulus
stimulus
 Removing desirable
 Removing unpleasant
stimulus
stimulus
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Using Habituation
to Study Infants
Figure 5.11
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Imitation
 Imitation is a powerful method of learning.
 It is more difficult to induce in babies 2 to 3
months old than right after birth.
 Andrew Meltzoff: Newborns imitate as much as
older children and adults.
 Mirror neurons enable us to observe another
person’s behavior while simulating that
behavior in our own brain.
 Meltzoff’s theory of newborn imitation as a
voluntary capacity is controversial.
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Imitation by
Human and
Chimpanzee
Newborns
Figure 5.12
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The Sequence of
Motor Development
Gross-motor development

Crawling, standing,
walking
Fine-motor development

Reaching and grasping
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Gross- and
Fine-Motor
Development
in the
First Two
Years
Table 5.2
Sources: Bayley 1969, 1993, 2005
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Motor Skills as Dynamic Systems
Increasingly complex
systems of action with
each skill
Four factors in each new
skill:
1.
2.
3.
4.
CNS development
Body’s movement capacity
Child’s goals
Environmental supports
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Cultural Variations in
Motor Development
Home environments and infant rearing
practices affect motor development.

Some cultures discourage rapid motor
progress.

Kipsigis of Kenya and the West Indians of
Jamaica teach early motor skills.

Western parents consider crawling and
“tummy time” essential, but not all cultures do.
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Milestones of Reaching
Figure 5.14
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Bowel and Bladder Control
Toilet training is best delayed
until the months following
the second birthday.
Effective training techniques
include


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
establishing regular toileting
routines.
using gentle encouragement.
praising children for their
effort .
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Developments in Hearing
4–7 months Sense of musical phrasing
“Screen out” sounds from non-native
6–8 months languages
7–9 months
Divide the speech stream into wordlike units
10 months
Can detect words that start with
weak syllables
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Improvements in Vision
Brain development helps
infants reach adult
levels of vision skills.
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2–4 months:
focus and color vision
6 months:
acuity, scanning, and
tracking
6–7 months:
depth perception
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Steps in Depth Perception
Birth–
1 month
Sensitivity to motion cues
2–3
months
Sensitivity to binocular cues
6–7
months
Sensitivity to pictorial cues
Wariness of heights
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Steps in Pattern Perception
3 weeks
 Poor contrast sensitivity
 Prefer large simple patterns
 Can detect fine-grained detail
2 months
 Prefer complex patterns
 Can detect patterns even if
4 months
boundaries are not really present
12
months
 Can detect objects if two-thirds
of drawing is missing
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Appearance of Checkerboards to
Very Young Infants
Figure 5.17
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Subjective
Boundaries in
Visual Patterns
Figure 5.18
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Early Face
Perception
Figure 5.19
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Testing Infants’ Ability to
Perceive Object Unity
Figure 5.20
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Intermodal Perception
World provides intermodal stimulation:
simultaneous input from more than one
modality, or sensory system
Intermodal perception: making sense of
multisensory input as integrated wholes



Infants can detect amodal sensory properties
even as newborns.
Abilities develop rapidly in first year.
Facilitates perception of physical world and
understanding of social world
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Differentiation Theory
of Infant Perception
Infants actively search for invariant, unchanging
features of the environment.

Borders of stimuli, faces

They note stable relationships between features.

Complex visual patterns, intermodal relationships
Perception gets more and more sensitive:
differentiation
Acting on the environment helps this process:
affordances
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Acting on the Environment
Plays a Major Role in
Perceptual Differentiation
Figure 5.21
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