The Developing Person Through Childhood and Adolescence
by Kathleen Stassen Berger
Seventh Edition
Chapter 5
The First Two Years:
Biosocial Development
Slides prepared by Kate Byerwalter, Ph.D.,
Grand Rapids Community College
Body Changes

An average newborn is 7½ lbs, 20 inches.

Infants triple their birthweight by 1 year.

By age two, they are about ½ their adult
height (!) and ¼ their adult weight.
Berger: The Developing Person Through Childhood and Adolescence, 7th Edition, Chapter 5
Body Changes
ALL: INES YVETTE LARAYA ERESE
Berger: The Developing Person Through Childhood and Adolescence, 7th Edition, Chapter 5
Body Changes (cont.)

Percentile ranks: allow comparisons of
an individual infant to group norms
 A sudden
drop in percentile rank might
indicate a developmental problem.

Head Sparing: in cases of inadequate
nutrition, the brain keeps growing
Berger: The Developing Person Through Childhood and Adolescence, 7th Edition, Chapter 5
The Wonderful World of SLEEP

Newborns sleep 17+ hours a day.
DAVID YOUNG-WOLFF / PHOTOEDIT, INC.
Berger: The Developing Person Through Childhood and Adolescence, 7th Edition, Chapter 5
Infant Sleep (cont.)

Infants gradually adjust to the family’s
sleep schedule.
 80%
of 1 year olds sleep “through the night”
 Sleep
cycles are influenced by brain
maturation, diet, child-rearing practices, and
birth order
Berger: The Developing Person Through Childhood and Adolescence, 7th Edition, Chapter 5
Make It Real: Co-Sleeping

Some families practice “co-sleeping,” in
which the family shares a bed.

Why might a family do this? Do you think it
could benefit or harm an infant?
Berger: The Developing Person Through Childhood and Adolescence, 7th Edition, Chapter 5
Research on Co-Sleeping

CULTURE influences the decision (it is
more common in Eastern culture)

It is not harmful to an infant, under normal
circumstances (e.g., if adult is not drunk)

It may increase dependence on parents
Berger: The Developing Person Through Childhood and Adolescence, 7th Edition, Chapter 5
Brain Development

Brain development during infancy is
fascinating and rapid.
 By
the age of 2, the brain is 75% its adult
weight
 Neural
connections in the brain also develop
Berger: The Developing Person Through Childhood and Adolescence, 7th Edition, Chapter 5
Berger: The Developing Person Through Childhood and Adolescence, 7th Edition, Chapter 5
Brain Development (cont.)

Regional specialization: neurons in
certain areas of the brain correspond to
different tasks
 Examples:
language, vision, smell, emotional
processing, recognizing faces vs. objects, etc.
Berger: The Developing Person Through Childhood and Adolescence, 7th Edition, Chapter 5
The Developing Cortex
Berger: The Developing Person Through Childhood and Adolescence, 7th Edition, Chapter 5
Brain Development (cont.)

Transient exuberance: rapid proliferation
of new neural connections in infancy
 As
many as 15,000 new connections per
neuron and 100 trillion synapses by age 2!

Pruning makes the brain more efficient by
eliminating underused connections.
Berger: The Developing Person Through Childhood and Adolescence, 7th Edition, Chapter 5
Berger: The Developing Person Through Childhood and Adolescence, 7th Edition, Chapter 5
What influences early brain
development?

Brain development is influenced by
maturation and experiences.

Experience-expectant brain functions
require basic common experiences.
 Example:
No matter where an infant lives, he
or she hears sounds and language.
Berger: The Developing Person Through Childhood and Adolescence, 7th Edition, Chapter 5
What influences early brain
development? (cont.)

Experience-dependent brain functions
depend on exposure to particular events.
 Example:
The particular sounds and language
heard (and learned) varies across infants.
 Example:
The development of impulse control
depends on both maturation and practice.
Berger: The Developing Person Through Childhood and Adolescence, 7th Edition, Chapter 5
Why are neural connections so
important?

A certain level of neural connections
indicate healthy brain development.

Lack of connections may result from
child abuse or neglect early in life, and can
have lasting consequences.
 Example:
Infants in orphanages
Berger: The Developing Person Through Childhood and Adolescence, 7th Edition, Chapter 5
Make it Real: Activities

Make a list of
toys and
activities that
can stimulate
healthy brain
development
in the first two
years of life.
PHOTODISC
Berger: The Developing Person Through Childhood and Adolescence, 7th Edition, Chapter 5
Implications for Caregivers

Is it possible to overstimulate an infant? YES!

The key is to follow the infant’s lead

Self-righting: an infant’s inborn drive to use
whatever experiences available to develop
the brain (wow!)
Berger: The Developing Person Through Childhood and Adolescence, 7th Edition, Chapter 5
Infant Senses

All five senses function at birth
 Vision,

hearing, taste, touch, smell
Perception (the brain’s processing of the
sensation) develops over time.
Berger: The Developing Person Through Childhood and Adolescence, 7th Edition, Chapter 5
Infant Senses (cont.)

Hearing: is well developed at birth
 Infants
respond to sudden noises, human
voice, phonemes of language

Vision: is the least mature sense at birth
 Bionocular
vision develops around 14 weeks
 “Adult” vision (20/20) by one year
Berger: The Developing Person Through Childhood and Adolescence, 7th Edition, Chapter 5
Infant Senses (cont.)

Taste, touch, smell function well at birth
All: CINDY CHARLES / PHOTOEDIT, INC.
Berger: The Developing Person Through Childhood and Adolescence, 7th Edition, Chapter 5
Motor Skills

Motor skills develop according to two
principles:
 Cephalocaudal:
growth proceeds from headto-toe (e.g., head lift before sit, stand, walk)
 Proximal-distal:
growth proceeds from torso
outward (e.g., sucking before kicking)
Berger: The Developing Person Through Childhood and Adolescence, 7th Edition, Chapter 5
Motor Skills (cont.)

Reflexes account for the first motor skills.

Survival reflexes include sucking,
breathing, body temperature.

Other reflexes include the Babinski, Moro,
and stepping reflexes.
Berger: The Developing Person Through Childhood and Adolescence, 7th Edition, Chapter 5
Infant Reflexes
ASTIER / BSIP / SCIENCE SOURCE / PHOTO
RESEARCHERS, INC.
JENNY WOODCOCK; REFLECTIONS
PHOTOLIBRARY / CORBIS
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Berger: The Developing Person Through Childhood and Adolescence, 7th Edition, Chapter 5
Make it Real: Motor Skills

At what age do
you think most
infants learn to
walk?

What about you?
PHOTODISC
Berger: The Developing Person Through Childhood and Adolescence, 7th Edition, Chapter 5
Berger: The Developing Person Through Childhood and Adolescence, 7th Edition, Chapter 5
Motor Skills (cont.)

Gross motor skills involve large muscle
movements.
 Examples:
crawling, sitting, walking
 Walking
typically occurs around 12 months,
with great variability across infants.
 Walking
requires muscle strength, brain
maturation, and practice.
Berger: The Developing Person Through Childhood and Adolescence, 7th Edition, Chapter 5
Motor Skills (cont.)

Fine motor skills involve small muscle
movements.
 Examples:
learning to grasp, shake, pull an
object, hold a spoon, write, draw, etc.

Motor skills are influenced by genes,
culture, and patterns of infant care.
Berger: The Developing Person Through Childhood and Adolescence, 7th Edition, Chapter 5
Public Health Measures

Infant survival rates have increased
significantly in the past century, due to
better nutrition, cleaner water, and
immunization.

Although not without controversy,
immunization has been hailed as a major
achievement (e.g., significantly reducing
polio, small pox, measles).
Berger: The Developing Person Through Childhood and Adolescence, 7th Edition, Chapter 5
Berger: The Developing Person Through Childhood and Adolescence, 7th Edition, Chapter 5
Sudden Infant Death Syndrome

SIDS is infant death of an unknown cause.

Protective factors (although not a
guarantee) include: NO cigarette smoke in
house, noise and touch during sleep,
breast feeding, sleeping on back
Berger: The Developing Person Through Childhood and Adolescence, 7th Edition, Chapter 5