Human Development - Lifespan (Infancy)

Topics: Developmental psychology, Jean Piaget, Infant Pages: 43 (5229 words) Published: October 3, 2013
Chapter 3: Infancy
Module 3.1: Physical Development in Infancy

Looking Ahead

Growth and Stability

An Interesting Head Count

Are there gender and ethnic differences in
infant weight and length?

Principles of Growth
Cephalocaudal principle
Proximodistal principle
Principle of hierarchical integration
Principle of independence of systems

Nervous System and Brain
Nervous system
comprises the brain
and the nerves that
extend throughout
the body
Neurons are the
basic cells of the
nervous system

Quick Check

Neurons

Dendrites
Axons
Neurotransmitters
Synapses

How great brains grow!
Birth:
100-200 billion
neurons
Relatively few
neuron-neuron
connections

During first two
years:
Billions of new
connections
established and
become more
complex

Use it or lose it!
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

Form and Function: Brain Growth
Neurons reposition themselves with growth,
becoming arranged by function
Cerebral cortex

Subcortical levels

Environmental Influences on Brain Development

Plasticity

Sensitive
period

What do babies do all day?
Life Cycles of Infancy
Wake

Defecate

Sleep

Eat

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

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 3-2)

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

Do babies dream?

Did you find examples in the text that
suggest that cultural practices affect infants’
sleep patterns?

SIDS
Sudden infant death syndrome
Leading cause of death in children under 1 year of age
Back-to-sleep guidelines (AAP)
Differential risk
Boys
African American infants
Low birthweight
Low APGAR scores
Mother’s smoking
Some brain defects
Child abuse

Declining Rates of SIDS

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!

Review and Apply
REVIEW
The major principles of growth are the
cephalocaudal principle, the proximodistal
principle, the principle of hierarchical integration,
and the principle of the independence of systems.
The development of the nervous system first
entails the development of billions of neurons and
interconnections among them. Later, the numbers
of both neurons and connections decrease as a
result of the infant’s experiences.

Review and Apply
REVIEW
Infants integrate their individual behaviors by
developing rhythms—repetitive, cyclical
patterns of behavior.
The sleep of infants often comes in fits and
starts initially coming in spurts of about two
hours, followed by periods of wakefulness.
Because of this, infants are “out of sync” with
the rest of the world, for whom sleep comes at
night and wakefulness during the day.

Review and Apply

APPLY
What evolutionary advantage could there be for
infants to be born with more nerve cells than
they actually need or use? How might our
understanding of synaptic “pruning” affect the
way we treat infants?

Motor Development

Reflexes: Inborn Physical Skills

Reflexes:

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

Why do reflexes come and go?

Ethnic and...
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