Families Can Be Together ForeverClick on the temple to start the video.

The Developing PersonThrough Childhood and Adolescence

Chapter 5The First Two Years: Biosocial Development

➢Body Changes

➢Brain Development

➢Senses and Motor Skills

➢Public Health Measures

Body Changes

• In infancy:

– growth is fast

– consequences of

neglect can be

severe

– gains need to be

monitored

• Check-ups need to

include:– measurement of height

– weight

– head circumference

• At birth the average infant weights 7 ½ lbs.

–Weight typically doubles by 4th month and triples by the first birthday.

–physical growth slows in 2nd year

–By 24 months weight is about 28-30 lbs, height about 32”-36”

–By 2 years height is half the adult height

• percentiles: numbers

fall between 0 and

100, with 50 being

exactly average.

– Actual percentile isn’t

as important as a

change in the

percentile

Percentile

• head-sparing: biological

mechanism that

protects brain

when malnutrition

affects body

growth

Sleep• New babies spend about 17 hours daily

sleeping.

• Regular sleep correlates with:

– normal brain maturation

– learning

– emotional regulation

– psychological adjustment

• Over the first month, amount of time in each stage of sleep changes.

• Newborns dream a lot with a high proportion of REM sleep.

• rapid eye movement sleep (REM): stage of sleep characterized by:

– flickering eyes

– dreaming

– rapid brain waves

– SLOW WAVE SLEEP: The term for a deeper, dreamless sleep state.

Dreaming and transitional sleep decline in the first few weeks.

• co-sleep: custom in which parents and children (usually infants) sleep together in the same room.

• co-bedding or bed-sharing: sleeping in the same bed.

• Breastfeeding is more common, but so is infant death

• Sleeping in the same room is beneficial; being in the same bed is not.

• Parent hear contradictory advice about this practice.– Parents in Asia, Africa, and Latin America favor co-sleeping.

– Western parents put infants to sleep in a crib in a separate bedroom.

Although co-sleeping infants awaken twice as often as

solo-sleeping infants (six versus three times a night)…

…co-sleeping babies got as much sleep as solo sleepers because they went back to sleep more

quickly.

• Newborn’s skull is disproportionately large.– at birth the brain is 25% of

the adult brain weight • body only 5% of the adult

weight

• By age 2 the brain is almost 75% of the adult brain weight.– Increase in brain

weight is due to the proliferation of dendrites in the first year of life.

Brain Development

Baby’s head proportion is large

-Nerve cells, called neurons, are created before birth,

at a peak production

rate of 250,000 new cells

per minute in

mid-pregnancy.

-In infancy, the human brain

has billions of neurons.

• Cortex: outer layers of the brain:

– most thinking, feeling, and sensing involve cortex

– contains all the neurons that make

conscious thought possible (70% of neurons are in the cortex)

– areas devoted to the basic senses mature earlier

• dendrite: fiber

that extends from

the neuron

– receives

electrochemical

impulses

transmitted from

other neurons via

their axons

• axon: fiber that

extends from a

neuron

– transmits

electrochemical

impulses to dendrites of other

neurons

Dendrites Sprouting

• synapse: intersection between the axon of one neuron and the dendrites of other neurons.

• Axons and dendrites do not touch at synapses. – the release of

chemicals called neurotransmitters are sent by electrochemical impulses.

• At birth the brain contains more

than 100 billion neurons.

– more than any person will ever use

• A fivefold increase in dendrites in

the cortex occurs in the 24 months

after birth.

– about 100 trillion synapses at age 2

– growth called transient exuberance

– transient - temporary

• Pruning occurs when the unused

neurons and disconnected dendrites

atrophy and die.

Transient Exuberance and Pruning

• self-righting: inborn drive to remedy a

developmental deficit

– Ex: toys

• Human brain designed to grow and adapt.

– some plasticity retained throughout life

– brain protects itself from overstimulation

• overstimulated babies cry or sleep

• understimulated babies adjust by developing

new connections based on minimal experiences

Because the prefrontal cortex is not developed yet,

telling infants to stop crying is

POINTLESS because they CANNOT decide to stop crying.

Such decisions require brain maturity.

Some adults react by SHAKING A BABY.

This can cause SHAKEN BABY SYNDROME.

Shaken baby syndrome is a life threatening

condition that occurs when

a baby is shaken back and forth.

Although it is successful in making the infant stop

crying, it is also successful in DEATH to the infant

• experience-expectantbrain functions– require certain basic

common experiences, which an infant can be expected to have in order to develop normally

• experience-dependent brain functions– depend on particular,

specific experiences

that may or may not be available.

Necessary & Possible

Experiences

• Necessary to develop a person’s potential:

– caressing newborn

– talking to preverbal infant

– showing affection toward a small child

– experience expectant: this is the minimum

needed for normal development

Implications

for

Caregivers

Lack of

stimulation-stunts the brain

Overstimulation-waste of time

and money

• Isolation and sensory

deprivation harm the

developing brain,

including social and

emotional development

– Ex: rat studies

– Ex: Romanian orphans

• Experienced catch-up

physical growth but were

emotionally damaged

• Children adopted after 6

months had 15 point lower IQ

Severe Social Deprivation

Romanian orphanages taught us

the importance of contact comfortfor normal development.

Self-

righting:

toys don’t

have

to be

expensive!

Piaget called the first

period of intelligence

the sensorimotor stage.

– Emphasized that

cognition

develops from

senses and motor

skills

Sensation

and

Movement

• Sensation: response of a sensory system to a stimulus

– eyes, ears, skin, tongue, nose

• Perception: mental processing of sensory information

when brain interprets a sensation

• Cognition: the mental action or process of acquiring

knowledge and understanding through thought,

experience, and the senses.

The Five Senses

• develops during last trimester

- acute at birth

- certain sounds trigger reflexes

• Young infants are particularly attentive to the human voice

• before comprehension babies understand:

- Rhythm

- Which syllable to stress

- Inflection (Chinese).

Hearing

• Vision is the least

mature sense at birth.

• Newborns are “legally

blind”

– focusing only on

objects between 4 and

30 inches away

• binocular vision: ability

to focus the two eyes

in coordinated

manner, usually

develops at 2-4 mos.

Seeing

Infant vision still undeveloped

The senses of smell, taste, and touch function at birth

and rapidly adapt to the social world.

Smelling, Tasting, and Touching

• Touch is comforting to normally developing

babies. Many different kinds of touch:

“wrapping,” caressing, patting, massage

etc.

• It is unknown when infants first feel pain;

they appear to feel it differently (both less

and more) than adults.

Touch

and

Pain

Babies need

touch!

• motor skills: learned

ability to move some

part of the body

• reflex: unlearned,

involuntary action or

movement emitted in

response to a

particular stimulus

Motor Skills

• All healthy babies

develop motor skills

in the same

sequence.

• The age of

acquisition varies

according to

culture.

• Depends on brain

maturation, muscle

development, and practice.

• Unusual delays are

a cause for

concern.Cultural Variations

FINE MOTOR SKILLS:

physical abilities involving

small body movement,

especially of hands and

fingers.

-2 months: excitedly wave

arms

-3 months: can touch

precise objects

-4 months: can grab, but

their timing is off

-6 months: with

concentration, can reach

for, grab, and hold onto an

object

gross motor skills:

physical abilities involving large

body movements, such as walking

and jumping

Sensation and Movement

Sitting:•By three months, babies

have sufficient muscle

control to be lap-sitters if

support is provided.

•By six months they can

usually sit unsupported.

Crawling:•By five months, babies can

use their arms and legs to

inch forward.

•By eight to ten months

they can usually lift their

midsection and crawl.

Walking:Walking progresses from

reflexive, hesitant, adult-

supported stepping to a

smooth, coordinated walk.

• By nine months , can step

while holding on

• By ten months, can alone

momentarily

• By twelve months, can

walk well, unassisted

Three needed factors:

• Muscle strength

• Brain maturation

• Practice

Infants respond to motion:

Ex: Driving, swinging the carseat, rocking

By six months, infants have learned to

coordinate the senses.

Dynamic Sensory Systems

Rocking, cars, swinging – baby loves

motion!Just don’t turn on their favorite song!

Click the baby to start the video.

• Immunization

– Dramatic Successes:

smallpox, polio, measles,

rotavirus.

– Problems with

Immunization: parental

concerns, more

independent studies needed.

– Autism rate is 1/45.

– What causes autism?

Surviving

in Good

Health

• sudden death syndrome (SIDS)– a seemingly healthy infant suddenly stops breathing and dies unexpectedly while sleeping

• “Back to sleep”

Sudden Infant

Death

Syndrome

• For most newborns, good

nutrition starts with mother’s milk

– Less likely to get sick

• breast milk provides

antibodies against any

diseases to which the

mother is immune.

• colostrum: thick, high-calorie

fluid secreted by woman’s breast

for first three days after birth

Nutrition: Breast is Best

Although breast is

best, breast milk may

be deficient in

Vitamin D.

Malnutrition• Chronically

malnourished

infants and

children suffer in

three ways:

– brains may not

develop normally

– have no body

reserves to protect

against common

disease

– some diseases result

directly from

malnutrition

Stunting: The failure

of children to grow

to a normal height

for their age due to

severe and chronic

malnutrition.

Wasting: The

tendency for

children to be

severely

underweight for

their age as a result

of malnutrition.

• kwashiorkor: disease of chronic malnutrition during childhood. Causes a distended belly.– makes child more

vulnerable to other diseases • measles

• diarrhea

• influenza

• Breathing reflex

– Also hiccups, sneezes, and thrashing

• To Maintain Body Temperature

– Cry, shiver, tuck legs

• To facilitate feeding

– Sucking, rooting, swallowing, spitting up

Reflexes

Critical for

Survival