Kathleen Stassen Berger
Part II
Chapter Five
The First Two Years: Infant and Toddlers
Body Changes
Brain Development
Senses and Motor Skills
Public Health Measures
Prepared by Madeleine Lacefield
Tattoon, M.A.
1
“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.”
2
• “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.”
3
“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.”
4
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
6
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
8
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”
9
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
10
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?”
13
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
15
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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Basic Brain Structures
• 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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Basic Brain Structures
• 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
20
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
22
Basic Brain Structures
• 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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Basic Brain Structures
• 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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Basic Brain Structures
• 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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Basic Brain Structures
• 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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Basic Brain Structures
• 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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Basic Brain Structures
• Implications for Caregivers
– 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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Basic Brain Structures
• Implications for Caregivers
– 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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Basic Brain Structures
• 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)
32
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
33
Sensation and Perception
– 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
34
Sensation and Perception
– 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
35
Senses and Motor Skills
– 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
36
Senses and Motor Skills
– Seeing
• At birth vision is the least mature
• The infant eyes are sensitive to bright light
even though the eyes open in midpregnancy
• Newborns are “legally blind” they can only
see objects 4” – 30” away
37
Senses and Motor Skills
– 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
38
Senses and Motor Skills
– Tasting, Smelling and Touching
39
Senses and Motor Skills
– 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
40
Senses and Motor Skills
– Early sensation seems to have two goals:
• Social interaction
– To respond to familiar caregivers
• Comfort
– To be soothed amid the disturbances of infant
life
41
Senses and Motor Skills
– 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)
42
Senses and Motor Skills
– 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
43
Senses and Motor Skills
– Reflexes
• Infants have dozen of reflexes
– three sets are critical for survival
» that maintain oxygen supply
» that maintain constant body temperature
» that manage feeding
44
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
45
Senses and Motor Skills
– Gross Motor Skills
• Three factors combine to allow toddlers to
walk
– muscle strength
– brain maturation within the motor cortex
– practices
46
Senses and Motor Skills
– 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
47
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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Senses and Motor Skills
49
Senses and Motor Skills
– Genes are only a small part of most ethnic
differences
– Cultural patterns of child rearing can affect
sensation, perception, and motor skills
50
Public Health Measures
– 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
52
Public Health Measures
– 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
55
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"
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