Transcript physical development in infancy

CHAPTER 4
PHYSICAL DEVELOPMENT IN
INFANCY
Learning Objectives
GROWTH AND STABILITY
Physical Growth:
The Rapid Advances of Infancy
Infants grow at a rapid pace over the first two years of their
lives (see Figure 4-1)
• 5 months: average birthweight doubles to around 15
pounds
• 1 year: weight triples to about 22 pounds
• End of 2nd year: average child weighs around four times
as much as he or she did at birth
See how they grow…
Physical Growth:
The Rapid Advances of Infancy
Not all parts of an infant's body grow at the same rate
• Birth: head accounts for one-quarter of the newborn's
entire body size
• During 1st and 2nd year: rest of the body begins to catch
up
An Interesting Head Count
Are there gender and ethnic differences in
infant weight and length?
Physical Growth:
The Rapid Advances of Infancy
Can you give an example of each principle?
Nervous System and Brain:
The Foundations of Development
• Neurons are the
basic cells of the
nervous system
• Nervous system
comprises the brain
and the nerves that
extend throughout the
body
How great brains grow!
Birth
• 100-200 billion neurons
• Relatively few neurons-neuron connections
During first two years
• Billions of new connections established and become
more complex
Use it or lose it!
Babies are actually born with many more neurons than they
need
• Although synapses are formed throughout life, based on our
changing experiences, the billions of new synapses infants
form during the first two years are more numerous than
necessary
• 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
Neuron Networks
Coming to terms with your brain…
Form and Function: Brain Growth
• Neurons reposition themselves with growth, becoming
arranged by function
– Cerebral cortex
– Subcortical levels
Don't shake the baby!
Shaken Baby Syndrome
• Brain sensitive to form
forms of injury
• Shaking can lead to brain
rotation within skull
– Blood vessels tear 
severe medical
problems, long-term
disabilities, and
sometimes death
Brain Development: Influences and Definitions
Brain
Development
• Environmental
Influences
Brain
Development
• Sensitive
Period
Brain
Development
• Plasticity
What do babies do all day?
Integrating the bodily systems: Life cycles of infancy
• Rhythms: repetitive, cyclical patterns of behavior
– Wake
– Sleep
– Eat
– Eliminate
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
• Electrical brain waves can be measured by
electrocephalogram (EEG)
Primary Behavioral States
Primary Behavioral States
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 4-2)
A Quick Review of Behavioral States
•
•
•
•
Awake
Non-alert
Fussing
Crying
Awake
Transition between
Sleeping and
Waking
• Drowse
• Daze
• Sleep-Wake
Transition
Transitional Sleep
States
• Active
• Quiet
• Active-Quiet
Transition
Sleep
Sleep
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
REM Sleep Through the Lifespan
Did you find examples in the text that suggest
that cultural practices affect infants’ sleep
patterns?
SIDS: The Unanticipated Killer
• Sudden infant death syndrome (SIDS) is a disorder in
which seemingly healthy infants die in their sleep
• SIDS strikes about 2,500 infants in the United States
each year
• Although it seems to occur when the normal patterns of
breathing during sleep are interrupted, scientists have
been unable to discover why that might happen
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 ____ principle,
the ____ principle, the principle of ____ ____, and the
principle of the ____ of systems.
• The development of the ____ system first entails the
development of billions of neurons and
interconnections among them.
• Later, the numbers of both ____ and ____ decrease as
a result of the infant's experiences.
Review and Apply
REVIEW
• ____ ____, the susceptibility of a developing organism to
environmental influences, is relatively high.
• Researchers have identified ____ periods during the development
of body systems and behaviors—limited periods when the
organism is particularly ____ to environmental influences.
• Babies integrate their individual behaviors by developing ____—
repetitive, cyclical patterns of behavior.
• A major rhythm relates to the infant's state—the awareness it
displays to ____ and ____ stimulation.
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
Motor Development
• Shape and proportions of newborn babies are simply not
conducive to easy mobility
• Young infants lack the strength to raise large heads
• Movement is further impeded because limbs are short in
relation to the rest of the body
• Infant bodies are mainly fat, with a limited amount of
muscle; the result is a lack strength
Motor Development
BUT
• At birth newborns have an extensive repertoire of
behavioral possibilities brought about by innate reflexes,
and their range of motor skills grows rapidly during the
first two years of life
Reflexes: Inborn Physical Skills
Reflexes
• Learned, organized involuntary responses that occur
automatically in presence of certain stimuli
Some Basic Reflexes in Infants
Some Basic Reflexes in Infants
Why do reflexes come and go?
Ethnic and Cultural Differences and Similarities
in Reflexes
Reflexes
• Genetically determined
• Universal
Cultural variations in ways displayed
• Moro reflex
Serves
• Diagnostic tool
• Social function
• Survival function
Milestones of Motor Development
Dynamic Systems
Dynamic systems theory
• Describes how motor behaviors are assembled
– Motor skills do not develop in vacuum
– Each skill advances in context of other motor abilities
– As motor skills develop, so do non-motoric skills
• Theory places emphasis on child's own motivation (a
cognitive state) in advancing important aspects of motor
development
Developmental Norms
Comparing Individual to Group Norms:
• Represent the average performance of a large sample of
children of a given age
• Permit comparisons between a particular child's
performance on a particular behavior and the average
performance of the children in the norm sample
• Must be interpreted with caution
• Brazelton Neonatal Behavior Assessment Scale
(NBAS)
Developmental Diversity
Cultural Dimensions of Motor Development
• Using information from your text, answer the following:
Does earlier emergence of a basic motor behavior in a
given culture has lasting consequences for specific motor
skills and for achievements in other domains?
Nutrition in Infancy
Fueling Motor Development
• Without proper nutrition, infants cannot reach physical
potential and may suffer cognitive and social
consequences
• Infants differ in growth rates, body composition,
metabolism, and activity levels
So what is a healthy caloric allotment for
infants?
• About 50 calories per day for each pound of weight
• Most infants regulate their caloric intake quite effectively
on their own
• If are allowed consume as much they seem to want, and
not pressured to eat more, they will be healthy
Malnutrition
Malnutrition
• Condition of having improper amount and balance of
nutrients, produces several results, none good
• More common in children living in many developing
countries
• Slower growth rate
• Chronically malnourished during infancy = later lower IQ
score
Underweight Children
Are problems of malnourishment restricted to
developing countries?
Undernutrition: Dietary Deficiencies
• Undernutrition also has long-term costs, including mild to
moderate cognitive delays
• Up to 25% of 1- to 5-year-old US children have diets that
fall below minimum caloric intake recommended by
nutritional experts
When Malnutrition Is Severe
Maramus
Kwashiorkor
• Malnutrition during first
year
• Infants stop growing.
• Attributable to severe
deficiency in proteins and
calories
• Causes the body to waste
away and ultimately
results in death
• Found in older children
• Child's stomach, limbs,
and face swell
• Body struggles to make
use of few available
nutrients
Nonorganic Failure to Thrive
• Sufficient nutrition
• Symptoms
• Reversal
“A fat baby is a healthy baby”?
Is Breast Best?
So What Is the Answer?
Breast milk
• Offers all nutrients infant needs for first 12 months of life
• Is more easily digested than alternative
• Provides some immunity to variety of childhood diseases
• May enhance cognitive growth
• Offers significant emotional advances for mother and
child
• Not cure-all for infant nutrition and health
Introducing Solid Foods: When and What?
• Solids can be started at 6 months but are not needed
until 9 to 12 months (AAFP)
– Introduced gradually, one at a time
– Cerealstrained fruits
• Time of weaning varies greatly in developed and
developing countries
Review and Apply
REVIEW
• Reflexes are ____, ____ acquired physical
behaviors.
• During infancy children reach a series of
milestones in their ____ development on a
fairly ____
schedule, with some individual
and ____ variations.
• Training and cultural expectations affect the
____ of
the development of ____ skills.
Review and Apply
REVIEW
• Nutrition strongly affects ____ development.
• ____ can slow ____, affect ____ performance,
and cause diseases such as marasmus and
kwashiorkor. The victims of undernutrition also
suffer negative effects.
• The advantages of breast-feeding are numerous,
including ____, ____, ____, and ____ benefits
for the infant, and physical and emotional
benefits for the ____ as well.
Review and Apply
APPLY
• What advice might you give a friend who is
concerned that her infant is still not walking at
14 months, when every other baby she knows
started walking by the first birthday?
The Development of the Senses
If all the lights in this room went out RIGHT NOW, what
would your senses tell you (sensation)?
What do you think about being in the dark with your class
(perception) or about an instructor who was crazy enough
to go to blackout to teach a concept (fill in this part
yourself)?
Learning the World
• Sensation
• Perception
Visual Perception: Seeing the World
• Newborn's distance vision ranges from 20/200 to 20/600
• By 6 months, average infant's vision is already 20/20
• Other visual abilities grow rapidly
– Binocular vision
– Depth perception
Infant Visual Preference
Preferences that are present
from birth
• Genetically preprogrammed to
prefer particular kinds of stimuli
• Prefer to look at patterned over
simpler stimuli
Facing the World
Genetics is not the sole determinant
of infant visual preferences
• A few hours after birth, infants have
already learned to prefer their own
mother's face to other faces
•
Similarly, between the ages of six
and nine months, infants become
more adept at distinguishing
•
between the faces of humans, while
they become less able to distinguish
faces of members of other species
•
They also distinguish between male
and female faces
Auditory Perception: The World of Sound
Infants
•Hear before birth and have good auditory perception after they are
born
•Are more sensitive to certain frequencies
•Reach adult accuracy in sound localization by age 1
•Can discriminate groups of different sounds
•React to changes in musical key and rhythm
•Can discriminate many language related sounds
•Are born with preferences for particular sound combinations which
may be shaped by prenatal exposure to mothers’ voices
Smell and Taste in a Small World
Smell
• Well developed at birth
• Helps in recognition of mother early in life
• Used to distinguish mother's scent (only in breast fed
babies); cannot distinguish father on basis of odor
Taste
• Have innate sweet tooth
• Show facial disgust at bitter taste
• Develop preferences based on what mother ate during
pregnancy
Ouch!
Contemporary Views on Infant Pain
• Today, it is widely acknowledged that infants are born
with the capacity to experience pain
• Developmental progression in reaction to pain
• Infants born with capacity to experience pain; produces
distress
• Exposure to pain in infancy may lead to permanent
rewiring of nervous system resulting in greater sensitivity
to pain during adulthood
The Power of Touch
• Touch is one of most highly developed sensory systems
in a newborn
• Even youngest infants respond to gentle touches
• Several of the basic reflexes present at birth require
touch sensitivity to operate
Multimodal Perception: Combining Individual
Sensory Inputs
New area of study in infant research
• Some researchers argue that sensations are initially
integrated with one another in the infant
• Others maintain that infant's sensory systems are initially
separate and that brain development leads to increasing
integration
• It does appear that by an early age infants are able to
relate what they have learned about an object through
one sensory channel to what they have learned about it
through another
What are affordances?
Perceptible affordances
• Exist where information on actions that are afforded are
perceptible
• These are dependent on language, culture, context, and
experience and vary for different individuals
Becoming an Informed Consumer of
Development
• Exercising Your Infant's Body and Senses
Attempts to accelerate physical and sensory-perceptual
development yield little success
but
infants need sufficient physical and sensory stimulation.
How can this be accomplished?
• Carry a baby in different ways
• Let infants explore their environment
• Engage in “rough-and-tumble” play
• Let babies touch their food and even play with it
• Provide toys that stimulate the senses, particularly toys
that can stimulate more than one sense at a time
Review and Apply
REVIEW
• ________ refers to the activation of the sense organs
by external stimuli.
• ________ is the analysis, interpretation, and
integration of sensations.
• Infants’ sensory abilities are surprisingly _____
_____ at or shortly after birth. Their perceptions help
they explore and begin to make sense of the world.
Review and Apply
REVIEW
• _____ _____, infants can see depth and motion,
distinguish colors and patterns, localize and
discriminate sounds, and recognize the sound and
smell of their mothers.
• Infants are sensitive to _____ and touch, and most
medical authorities now subscribe to procedures,
including anesthesia, that minimize infants’ pain.
• Infants also have a keen ability to integrate
information from _____ ______.
Review and Apply
REVIEW
• Infants’ sensory abilities are surprisingly ____
____ at or shortly after birth. Their ____ help
them explore and begin to make sense of the
world.
• Very early, infants can see ____ and ____,
distinguish ____ and patterns, localize and
discriminate sounds, and recognize the ____
and ____ of their mothers.
Review and Apply
APPLY
• What might be the advantages and disadvantages of
swaddling, a practice in which a baby is snuggly
wrapped in a blanket and which usually calms an
infant?
• Persons who are born without the use of one sense
often develop unusual abilities in one or more other
senses. What can healthcare professionals do to
help infants who are lacking in a particular sense?
EPILOGUE
Turn back for a moment to the prologue of this chapter,
about a baby's first steps, and answer these questions:
• Which principles of growth (i.e., cephalocaudal, proximodistal,
heirarchical integration, independence of systems) account(s)
for the progression of physical activities that precedes Josh's
first steps?
• What conclusions about Josh's future physical development
can be drawn based on the fact that his first steps occurred
approximately two months early?
• Can conclusions be drawn about his future cognitive
development? Why?
EPILOGUE
• In walking at 10 months of age, Josh outpaced his little
brother Jon by four months. Does this fact have any
implications for the comparative physical or cognitive
abilities of the two brothers? Why?
• Do you think anything changed in the environment
between the time Jon and Josh were born that might
account for their different “first step” schedules? If you
were researching this question, what environmental
factors would you look for?
EPILOGUE
• Why were Josh's parents so pleased and proud about
his accomplishment, which is, after all, a routine and
universal occurrence? What cultural factors exist in the
U.S. culture that make the “first steps” milestones so
significant?