Physical and Cognitive Development
in Infancy
CHAPTER 3
Physical Growth and Development in
Infancy

Head
 large
relative to the rest of the body
 flops around uncontrollably

Infant becomes capable of
 Rolling
over
 Sitting
 Crawling
 standing
 stooping
 climbing
 usually
walking
The First Year
Average North American newborn -- 20 inches
long; 7½ pounds
 Most newborns lose 5 to 7 percent of their
body weight adjusting to feeding
 They double their birth weight by the age of 4
months; nearly triple it by their first birthday
 Infants grow about 1 inch per month during the
first year

From Age 1 to 2 Years

At 2 years of age, children weigh
approximately 26 to 32 pounds
 gaining
a quarter to half a pound per month
 attain about one-fifth of their adult weight

At 2 years, the average child is 32 to 35
inches tall
 nearly
half of their eventual adult height
The Brain
Cerebral cortex covers the forebrain like a
wrinkled cap
 Two halves, or hemispheres, based on ridges
and valleys in the cortex
 Lateralization -- specialization of function in
one hemisphere or the other

 Example:
Spatial ability
Neuron

Parts of the neuron
 Axon carries signals away from the cell body
 Dendrites carry signals toward it
 Myelin sheath -- a layer of fat cells -- provides
insulation and helps electrical signals travel faster
down the axon
 At the end of the axon are terminal buttons, which
release chemicals called neurotransmitters into
synapses
 Synapses -- tiny gaps between neurons' fibers
 Transient exuberance
Changes in Neurons


The infant’s brain is literally waiting for experiences to
determine how connections are made
Experience enhances brain development
 Experience-expectant

brain growth
Examples: Maturation, eating, sensory
 Experience-dependent

brain growth
Examples: Language, siblings, parent interaction
Changes in Regions of the Brain
Both heredity and environment influence
synaptic overproduction and subsequent
retraction
 Pruning -- unused connections are replaced by
other pathways or disappear
 Prefrontal cortex -- the area of the brain
where higher-level thinking and self-regulation
occur

Sleep

Considerable individual variation in how much
infants sleep
 typical
newborn sleeps 16 to 17 hours a day
 preferred times and patterns of sleep also vary

Infants spend a greater amount of time in REM
(rapid eye movement) sleep
 by
3 months of age, the percentage of time in REM
sleep decreases
SIDS
Sudden infant death syndrome (SIDS) -condition that occurs when infants stop
breathing, usually during the night, and die
suddenly without an apparent cause
 SIDS is the highest cause of infant death in the
United States

 Risk
of SIDS is highest at 2 to 4 months of age
Risk Factors for SIDS
SIDS decreases when infants sleep on their backs
 More common in low birth weight infants
 Infants who are passively exposed to cigarette
smoke are at higher risk
 More frequent in infants who sleep in
soft bedding or use a pacifier when they go to
sleep

Benefits of Breast Feeding






Appropriate weight gain and lowered risk of
childhood obesity
Fewer allergies
Prevention or reduction of diarrhea, respiratory
infections, bacterial and urinary tract infections, and
otitis media
Denser bones in childhood and adulthood
Reduced childhood cancer and reduced incidence of
breast cancer in mothers and their female offspring
Lower incidence of SIDS

When should a mother not breast feed ?
Nutritional Needs
Nutritionists recommend that infants consume
approximately 50 calories per day for each
pound they weigh
 This is more than twice an adult’s requirement
per pound
 Many U.S. parents are feeding their 4- to 24month-old babies too few fruits and
vegetables, and too much junk food

Reflexes


Reflexes -- built-in reactions to stimuli – automatic,
involuntary
Allow infants to respond adaptively to their
environment

Examples: Rooting and sucking, Moro or startle reflex,
coughing, sneezing, blinking, shivering, and yawning
Gross Motor Skills

Skills that involve large-muscle activities
 Sitting
with support -- 2 months
 Sitting upright without support -- 6 to 7 months of
age
 Pull themselves up and hold on to a chair -- 8
months
 Stand alone – 10 to 12 months
Gross Motor Development in the Second
Year
Toddlers become more mobile
 13–18 months

can pull a toy attached to a string
 use their hands and legs to climb up a number of steps


18–24 months
toddlers can walk quickly or run stiffly
 walk backwards without losing their balance
 stand and kick a ball without falling and stand and throw a
ball
 jump in place

Fine Motor Skills

Finely tuned movements
 anything
that requires finger dexterity
At birth, infants have very little control over
fine motor skills
 During the first two years of life, infants refine
how they reach and grasp

 Perceptual-motor
coupling is necessary for the
infant to coordinate grasping
 Experience plays a role in reaching and grasping
Sensory and Perceptual Development

Sensation occurs when information interacts
with sensory receptors -- the eyes, ears, tongue,
nostrils, and skin
 Example:

Everything…
Perception is the interpretation of what is
sensed
 Example:
Mommy, foods, HOT!
Studying the Infant’s Perception



Visual Preference Method -- Infants look at different
things for different lengths of time
Orienting response -- to determine if an infant can
see or hear a stimulus
Habituation -- decreased responsiveness to a stimulus
after repeated presentations of the stimulus


Examples: Pacifier, holding hands, football game?
Dishabituation -- is the recovery of a habituated
response after a change in stimulation

Example: sleeping in the car…
Visual Acuity and Color
Newborn’s vision is estimated to be 20/600 on
the well-known Snellan eye examination chart
 By 6 months of age -- vision is 20/40 or better
 By about the first birthday, the infant’s vision
approximates that of an adult
 By 8 weeks, possibly even by 4 weeks, infants
can discriminate among some colors


(Banks & Salapatek, 1983; Aslin & Lathrop, 2008)
Perception of Pattern and Depth

Infants prefer to look at a normal human face
rather than one with scrambled features
 Can
babies detect attractiveness?
They prefer to look at a bull’s-eye target or
black-and-white stripes rather than a plain
circle
 Depth perception -- visual cliff

 Infants
develop the ability to use binocular (twoeyed) cues to depth by about 3 to 4 months of age
(Gibson & Walk, 1960)
Hearing, Touch, and Pain
Prenatally at 7 months, infants can hear sounds
such as mother’s voice and music
 Immediately after birth, infants cannot hear soft
sounds or pitch as well as adults do
 Newborns respond to touch and feel pain
 Infants also display amazing resiliency

 Within
several minutes after the circumcision surgery
(which is performed without anesthesia), they can
nurse and interact in a normal manner with their
mothers
Smell and Taste

Newborns can differentiate among odors
 Example:
Mom vs. Dad
Sensitivity to taste might be present even
before birth
 At only 2 hours of age, babies made different
facial expressions when they tasted sweet, sour,
and bitter solutions
 At about 4 months of age, infants begin to
prefer salty tastes, which as newborns they had
found to be aversive

(Windle, 1940; Rosenstein & Oster, 1988; Harris, Thomas, & Booth, 1990)
Piaget’s Theory of Cognitive
Development


Piaget thought we build mental structures that help us
to adapt to the world
Adaptation involves adjusting to new environmental
demands
Processes of Development



Developing brain creates schemes, which are actions or mental
representations that organize knowledge
Assimilation -- children use their existing schemes to deal with
new information or experiences
 Examples: Banging, chewing, dropping, hot dirt, parties
Accommodation -- children adjust their schemes to take new
information and experiences into account
 Examples: no cats!, get splashed

Examples: Juice, in the hoop, “Bye, Bye”
(Lamb, Bornstein, & Teti, 2002)
Equilibrium and Disequilibrium

Cognitive conflict -- disequilibrium


the child is constantly faced with inconsistencies and
counterexamples to existing schemes
An internal search for equilibrium creates motivation
for change

the child assimilates and accommodates, develops new
schemes, and organizes and reorganizes old and new
schemes
Sensorimotor Stage

Sensorimotor intelligence: From birth to 2 years:
infants construct an understanding of the world by
coordinating sensory experiences (such as seeing and
hearing) with physical actions
Cognitive Development

Sensorimotor stage
 Primary
circular reactions
 Stage
1: Stage of reflexes

 Stage
Examples: Sucking, arms up!
2: First acquired adaptation

Examples: Bottle vs. pacifier, crying
Sensorimotor Stage

Secondary circular reactions
 Stage
3: Make interesting events last

Examples: Rattle on table, bouncing, Peek-a-boo, ripping
paper
 Stage
4: New adaptation and anticipation or “The
means to the end”

 Object

Examples: The “drop game,” books, Exersaucer, feeding
Mommy, size
permanence
Examples: Mommy, keys, which hand?
Object Permanence



One of the infant’s most important accomplishments
Watch an infant’s reaction when an interesting object
disappears. If the infant searches for the object, it is inferred
that the baby knows it continues to exist
A-not-B error is the term used to describe the tendency of
infants to reach where an object was located earlier rather
than where the object was last hidden
Sensorimotor Stage

Tertiary circular reactions

Stage 5: New means through active experimentation

 Little
scientist


Example: Cabinet, water
Examples: Beans, vacuum
Stage 6: Mental representations

Example: Little cowboy…, bandaid
 Deferred

imitation
Examples: DVD, spanking
 Make-believe

play
Examples: Dolls, trucks, “Sip…” “Bite…”
Learning, Remembering, and
Conceptualizing

Infants can learn through operant conditioning



Examples: Reading a book, building a castle, using signs
Attention is the focusing of mental resources on select
information and improves cognitive processing on
many tasks
Joint attention involves individuals focusing on the
same object or event and involves:
 The ability to track another’s behavior
 One person directing another’s attention
 Reciprocal interaction
Learning, Remembering, and
Conceptualizing



Meltzoff (2007) concludes that infants don’t blindly
imitate everything they see and often make creative
errors
He argues that beginning at birth there is an interplay
between learning by observing and learning by doing
Critics say the newborns simply engage in automatic
responses to a stimulus
Learning, Remembering, and
Conceptualizing





Memory involves the retention of information over time
Some infants as young as 2 to 6 months can remember
some experiences through 1½ to 2 years of age
Implicit memory refers to memory without conscious
recollection
Explicit memory refers to conscious memory of facts
and experiences
Infantile or childhood amnesia -- few memories before
age 3
Language Development
Language -- a form of communication—
whether spoken, written, or signed—that is
based on a system of symbols
 All human languages have some common
characteristics

 Rules
describe the way the language works
 Infinite generativity -- the ability to produce an
endless number of meaningful sentences using a
finite set of words and rules
(Berko Gleason, 2009)
Key Milestones in Language Development

Babies' sounds and gestures go through this sequence
during the first year
 Crying: can signal distress, but there are different types of
cries that signal different things
 Cooing: about 1 to 2 months, gurgling sounds that are
made in the back of the throat and usually express pleasure
during interaction with the caregiver
 Babbling: In the middle of the first year, babies babble -strings of consonant-vowel combinations, such as “ba, ba,
ba, ba”
 Gestures: Infants start using gestures, such as showing and
pointing, at about 8 to 12 months of age

Example: simple signs (operant conditioning)
Recognizing Language Sounds
First words occur between 10 to 15 months
(average is 13 months)
 Overextension -- the tendency to apply a word
to objects that are inappropriate for the word’s
meaning
 Underextension -- the tendency to apply a
word too narrowly


Examples: Duck, Shoes, Train
Two-Word Utterances

Occurs by the time children are 18 to 24
months of age
 “Big
ball”
 “Where cat?”

Telegraphic speech is the use of short, precise
words without grammatical markers such as
articles, auxiliary verbs, and other connectives
 “Mommy
hold you”
 “No mo’ monkey jump bed…”
Biological Influences



The ability to use language requires vocal apparatus
as well as nervous system capabilities
Brain regions predisposed for language
 Broca’s area -- an area in the left frontal lobe of
the brain involved in producing words
 Wernicke’s area -- a region of the brain’s left
hemisphere involved in language comprehension
Aphasia -- a loss or impairment of language
processing as a result of damage to brain
Biological Influences

Language Acquisition Device (LAD) -- Humans
are biologically prewired to learn language at
a certain time and in a certain way and to
detect the various features and rules of
language
Environmental Influences

Behaviorists opposed Chomsky's LAD hypothesis


The behavioral view is no longer considered a viable
explanation of how children acquire language


Stated that language was nothing more than chains of
responses acquired through reinforcement
Example: Not all imitation: “I runded…”
Language is not learned in a social vacuum

Most children learn at a very early age
Environmental Influences


Vocabulary development is linked to the family’s socioeconomic
status and the type of talk that parents direct to the child
Compared to professional parents, parents on welfare:





Talked much less to young children
Talked less about past events
Provided less elaboration
Child-directed speech is language spoken in a higher pitch
than normal, using simple words and sentences
Other strategies include recasting, expanding, labeling