chapter 5 (psych 41)pdf

Kathleen Stassen Berger

Prepared by Madeleine Lacefield

Tattoon, M.A.

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Part II

The First Two Years: Infant and Toddlers

Chapter Five

Body Changes

Brain Development

Senses and Motor Skills

Public Health Measures

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―Adults don’t change much in a year or two.

Their hair might grow longer, grayer, or thinner; they might be a little fatter; or they might learn something new.

But if you saw friends you hadn’t seem for two years, you’d recognize them immediately.‖

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• ―By contrast, if you cared for

newborn 24 hours a day for a

month, went away for two years,

and then came back,you might

not recognized him or her,

because the baby would have

quadrupled in weight, grown

taller by more than a foot, and

sprouted a new head of hair.

• Behavior would have changed,

too. Not much crying, but some

laughter and fear—including of

you.‖

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―A year or two is not much compared

with the 75 or so years of the

average life span. However, in two

years newborns reach half their adult

height, talk in sentences, and

express almost every emotion—not

just joy and fear but also love,

jealousy, and shame.‖

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Biosocial Development

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Body Changes

– In infancy

• growth is fast

• neglect can be severe

• gain needs to be monitored

• health check-up need to include

– height, weight and head circumference

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Body Size

• rapid growth

• infants typically double their birth weight by

the 4th month and triple by the 1st birthday

• physical growth slows in the 2nd year

• by 24 months weight is about 30 lbs, height

about 32‖-36‖

– these numbers are ―norms‖

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Body Size

• ―norms‖– an average or standard for a particular population

• ―particular population‖– a representative sample of North American infants

• ―percentiles‖– a number that is midway between 0 and 100, with ½ the

children above it and ½ below it

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Body Size

• Weight increase in the early months is fat, providing insulation for warmth and nourishment

• Nourishment keeps the brain growing, if teething or illness interfere with eating

• When nutrition is temporarily inadequate, the body stops growing but not the brain

– this is known as a phenomenon called ―head-sparing‖

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Sleep• Infants sleep about 17 hours or more a day

• Regular and ample sleep correlates with normal brain

maturation, learning, emotional regulation, and

psychological adjustment in school and within the family

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Sleep

• Over the first month the amount of time spent in

each type or stage of sleep changes

• Newborns dream a lot, or at least they have a high

proportion of ―REM sleep‖

– REM sleep

• rapid eye movement sleep is a stage of sleep

characterized by flickering eyes behind closed lids,

dreaming, and rapid brain waves

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Sleep• Sleep Patterns can be…

– affected by birth order

• first born typically receive more attention

– diet

• parents might respond to predawn cries with food,

and/or play (babies learn to wake up night after

night)

– child-rearing practices

• ―Where should infants sleep?‖

– co-sleeping or bed-sharing

– brain maturation

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―Who Sleeps Where?‖

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Brain Development

– the newborn’s skull is disproportionately large

– large enough to hold the brain, which at birth is 25%

of the adult brain

– the neonate’s body is typically 5% of the adult weight

– by age 2 the brain is almost 75% of the adult brain

weight

– the child’s total body weight is only about 20% of its

adult weight

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Connection in the Brain

– Head circumference provides a rough idea

of how the brain is growing, and that is why

medical checkups include measurement of

the skull.

– Head typically increases about 35% within

the 1st year

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Basic Brain Structures

– The brain’s communication system begins with nerve

cells, called neurons.

• Neurons are one of the billions of nerve cells in the

central nervous system, especially the brain.

– Infants have billions of neutrons

• Located in the brain or in the brain stem

– the region that controls automatic responses,

I.e., heartbeat, breathing, temperature, and

arousal

• 70% of the neurons are in the cortex

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• The cortex is crucial for humans…

– 80% of the human brain materials in the cortex

– in other mammals the cortex is proportionally

smaller, and non-mammals have no cortex

– most thinking, feeling, and sensing take place

in the cortex, although other parts of the brain

join in.

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• Areas of the cortex specialize

in particular functions:

– visual

– auditory

– an area dedicated to the

sense of touch for each

body part

– regional specialization

within the cortex occurs

not only for motor skills

and senses but also for

aspects of cognition

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Basic Brain Structures• Between brain areas, neurons are

connected to other neurons by intricate networks of nerve fibers called axons and dendrites

– a neuron has a single axon and numerous dendrites, which spread out like the branches of a tree

– axons and neurons meet the dendrites of other neurons at intersections called synapses which are critical communication links within the brain

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Basic Brain Structures • Transient Exuberance and Pruning

– The fivefold increase in dendrites in the cortex

occurs in the 24 months after birth, with about

100 trillion synapses being present at age 2

– The expanded growth is followed by pruning in

which unused neurons and misconnected

dendrites atrophy and die

– Synapses, dendrites, and even neurons continue

to form and die throughout life, though more

rapidly in infancy than at any other time

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Basic Brain Structures • Experience Shapes the Brain

– brain structure and growth depends on genes and

experiences

– experiences produce ―postnatal rise and fall‖

– some dendrites wither away because they are

underused; no experiences have caused them to

send a message to the axons of other neurons.

– increasing cognitive complexity of childhood is related

to a loss of synapses

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• Stress and the Brain

– example of the role of experience in brain

development begins when the brain

produces cortisol and other hormones in

response to stress, which happen

throughout life

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• Necessary and Possible Experiences

– Scientist William Greenough identified two

experience-related aspects of brain development

• The development of experience-expectant

referring to brain functions that require certain

basic common experiences, which an infant can

be expected to have in order to develop normally

• The development of experience-dependent

referring to brain functions that depend on

particular, variable experience and that therefore

may or may not develop in a particular infant

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• Necessary and Possible Experiences– Basic, common experiences must happen for

normal brain maturation to occur, and they almost always do happen• The brain is designed to expect them and use them

for growth

– in contrast, dependent experiences might happen. Because of them, one brain differs from another

– experience varies; language babies hear or how their mothers reacts to frustration

– all people are similar, but each person is unique, because of early experiences

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• Necessary and Possible Experiences– The last part of the brain to mature is the

prefrontal cortex

• The area for anticipation, planning, and impulse control– Virtually inactive in early infancy

» telling an infant to stop crying is pointless

» shaking a baby to stop crying, ―shaken baby syndrome,‖ is useless

– Gradually becomes more efficient over the years of childhood and adolescence

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• Implications for Caregivers

– Early brain growth is rapid and reflects

experience…

• caressing a newborn,

• talking to a preverbal infant

• showing affection toward a small person

– …are essential to develop that person’s full

potential

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Basic Brain Structures• Implications for Caregivers

– Each part of the brain has sequence of…

• growing

• connecting

• pruning

– Stimulations are meaningless before the brain is

ready

• advisable to follow the baby’s lead

• infants respond most strongly and positively to their

brain’s need

– Self-righting is the inborn drive to remedy a

developmental deficit

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– the human brain is designed to grow and

adapt

• some plasticity is retained throughout life

• the brain protects itself from overstimulation

– ex., overstimulated babies cry or sleep

• babies adjust to understimulation

– by developing new connections lifelong

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– Neuroscientist once thought that brains were

influenced by

• Genes and prenatal influences

– By contrast, social scientist by

• Childhood environment was crucial…

– Cultures

– Societies

– Parents

• …credited or blamed for child’s emotions and/or

actions

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• THINK LIKE A SCIENTIST

– Plasticity and Orphans

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Senses and Motor Skills– Piaget called the first period of

intelligence the

• Sensorimotor stage

– cognition develops from the

senses and motor skills

– infant brain development depends

on sensory experiences and early

movement

• within hours of birth vital organs are

functioning, assessing basic senses

and motor responses (Brazelton

Neonatal Assessment Scale;

measures 26 items of newborn

behavior)

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Sensation and Perception

– All the senses function at birth

• open eyes, sensitive ears, and responsive

noses, tongues, and skin

– Very young babies attend to everything

• Infants don’t focus on anything in particular

• To about age one taste in the primary way

humans learn about objects

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– Sensation is the response of a sensory

system…

• eyes, ears, skin, tongue, nose

– …when it detects a stimulus

• when the inner ear reverberates with sound

• The retina and pupil of the eye intercept

light

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– Perception is the mental processing of

sensory information…

• the brain notices and processes a

sensation…

– when the brain interprets a sensation…

– Infant’s brains are attuned to experiences

that are repeated, striving to make sense

of them

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– Hearing

• Hearing is acute at birth

• Certain sounds trigger reflexes

• Sudden noises startle newborns

• Rhythmic sounds soothe them and put them to

sleep

• The first days of life infants turn their heads

towards sound

• They soon connect sight and sound with accuracy

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– Seeing

• At birth vision is the least mature

• The infant eyes are sensitive to bright light

even though the eyes open in mid-

pregnancy

• Newborns are ―legally blind‖ they can only

see objects 4‖ – 30‖ away

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– Seeing

• At two months infants look more intensely

at faces and often smile

• At three months infants look more closely

at the eyes and mouth

– The ability to focus the two eyes in a

coordinated manner in order to see one

image is known as binocular vision

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– Tasting, Smelling and Touching

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– Tasting, Smelling and Touching

• At birth the senses of taste, smell and touch

function and rapidly adapt to the social

world

• As infants learn their caregiver’s smell and

touch (handling) they relax and cuddle

• Over time infants become responsive to

whose touch it is and what it communicates

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– Early sensation seems to have two goals:

• Social interaction

– To respond to familiar caregivers

• Comfort

– To be soothed amid the disturbances of infant

life

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– Motor Skill is the learned ability to move

some part of the body, from a large leap

to a flicker of the eyelid.

(motor refers to movement of muscles;

the abilities needed to move and control

the body)

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– Reflexes are a responsive movement

that seems automatic because it almost

always occurs in reaction to a particular

stimulus. Newborns have many reflexes,

some of which disappear with

maturation (a reflex is an involuntary

response to a particular stimulus

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– Reflexes

• Infants have dozen of reflexes

– three sets are critical for survival

» that maintain oxygen supply

» that maintain constant body temperature

» that manage feeding

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Senses and Motor Skills– Gross Motor Skills are physical abilities involving

large body movements (gross meaning ―big‖)

• walking

• jumping

– Walking progress

• from reflexive,

• to hesitant

• to adult-supported stepping

• to a smooth coordinated gait

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– Gross Motor Skills

• Three factors combine to allow toddlers to

walk

– muscle strength

– brain maturation within the motor cortex

– practices

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– Fine Motor Skills are physical abilities

involving small body movements,

especially of the hands and fingers (fine in

this text means ―small‖)

• drawing

• picking up a coin

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Senses and Motor Skills– Ethnic Variation

• healthy infants develop skills in the same sequence

• they vary in the age at which they acquire them (the

table on the next slide show some ―norms‖)

– Walking, when grouped by ethnicity:

• Generally African American are ahead of Hispanic

Americans

• Hispanic American are ahead of European American

• Internationally the earliest walkers are in Uganda

• The latest walkers are in France

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– Genes are only a small part of most ethnic

differences

– Cultural patterns of child rearing can affect

sensation, perception, and motor skills

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– 8 billion children were born between 1950

– 2005

– 2 billion died before age 5

• Deaths could be twice this if not for:

– Child care

– Preventive care – immunization

– Clean water

– Adequate nutrition

– Medial treatment, etc.

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Public Health Measures– Immunization is a process that stimulates the body’s immune

system to defend against attack by a particular contagious

disease (immunization acquired either naturally, by having the

disease or though vaccination)

• immunization successes

– Smallpox

– Polio

– Measles

• problem with immunization

– parents don’t notice if their children does not get seriously

ill

– minor disease can kill

– parents are concern about side effects of vaccinations

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– Sudden Infant Death Syndrome (SIDS)

• die unexpectedly in their sleep

• No apparent cause of death

• 1990 in the U.S., 5000 babies died of SIDS,

1 in 800

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ISSUES AND APPLICATONS

Back to Sleep

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Nutrition

• has been discuss indirectly throughout

the chapter

• Breast is Best

– Good nutrition starts with mother’s milk

» Colostrum, a thick, high-calorie fluid secreted by the

woman’s breast at the birth of a child.

» About 3 days later the breast begins to produce milk

» Breast fed babies are less likely to get sick

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Nutrition

– Malnutrition

• protein-calorie malnutrition is a condition in which a person does not consume sufficient food of any kind

• the deprivation can result in several illnesses, severe weight loss, and sometimes death

• to measure a child’s nutritional status, compare weight and height with the "norms"

chapter 5 (psych 41)pdf

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