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Title: Infancy: Physical Development


1
Infancy Physical Development
  • Chapter 4
  • Development Across the Life Span

2
Growth and Stability Physical Growth
  • Over the first 2 years of a humans life, growth
    occurs at a rapid pace!

3
Height Weight Growth
The greatest height weight increases occur
during the 1st year of life, but children
continue to grow through infancy toddlerhood.
4
  • Average birthweights
  • (progression through the 1st 2 years)

--By age 5 months, the average infant's
birthweight has doubled to about 15 pounds. --By
age 1, the infants' birthweight has tripled to
approximately 22 pounds. --By the end of its
second year, the average child weighs four times
its birthweight. --By age 1, the average baby
stands 30 inches tall. --By the end of the
second year the average child is three feet tall.

5
Decreasing Proportions
At birth, the head is ¼ of the neonates body. By
adulthood, it is only 1/8th the size of the body.
6
? Not all parts of the body grow at the same
rate. The 4 Major Principles Governing Growth
  • 1) The CEPHALOCAUDAL PRINCIPLE states that growth
    follows a pattern that begins with the head and
    upper body parts and then proceeds to the rest of
    the body.
  • 2) The PROXIMODISTAL PRINCIPLE states that
    development proceeds from the center of the body
    outward.

7
(Major Principles Governing Growth continued)
  • 3) The PRINCIPLE OF HIERARCHICAL INTEGRATION
    states that simple skills typically develop
    separately and independently but are later
    integrated into more complex skills.
  • 4) The PRINCIPLE OF INDEPENDENCE OF SYSTEMS
    suggests that different body systems grow at
    different rates.

8
Maturation Rates
Different body systems mature at different rates.
For instance, the nervous system is highly
developed during infancy.
9
The nervous system comprises the brain and the
nerves that extend throughout the body.
  • ? Infants are born with between 100 and 200
    billion NEURONS! ( the nerve cells of the nervous
    system).
  • ? As the infant's experience in the world
    increases, neurons that do not become
    interconnected become unnecessary and die off.

10
The Neuron
The basic element of the nervous system
11
More About Neurons
  • -- Neurons increase in size.
  • -- Neurons become coated with MYELIN, a fatty
    substance that helps insulate neurons and speeds
    transmission of nerve impulses.
  • -- The brain is made up of neurons, and triples
    its weight in the first two years of life.
  • The infant's brain is 3/4 its adult size by age
    two

12
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13
More About Neurons
  • As they grow, neurons become arranged by
    function.
  • Some move into the CEREBRAL CORTEX, the upper
    layer of the brain.
  • Others move to subcortical levels, which
    regulate fundamental activities such as breathing
    and heart rate (and are below the cerebral
    cortex).

14
Networks of neurons become more complex over the
first few years of life.
Neuron Networks
15
PLASTICITY is the degree to which a developing
structure (e.g., the brain) or behavior is
susceptible to experience
Brain development occurs because of genetic
patterns and environmental influences.
  • ? The brain is relatively plastic
  • -- Infants who grow up in severely restricted
    environments are likely to show differences in
    brain structure and weight.

16
(brain development, continued)
  • -- Research with non-humans reveals that a
    SENSITIVE PERIOD exists which is a specific but
    limited time span, usually early in an organism's
    life, during which the organism is particularly
    susceptible to environmental influences relating
    to some particular facet of development.

17
Development of Body Rhythms
  • Behavior (sleeping, eating, crying, attending to
    the world) becomes integrated through the
    development of various body RHYTHMS (repetitive,
    cyclic patterns of behavior)
  • Some rhythms are obvious/easy to notice
  • The change from being asleep to being
    awake/breathing patterns

18
(development of body rhythms, continued)
  • Some rhythms are more subtle
  • Jerking suddenly while sleeping
  • Some are apparent right after birth, others
    emerge over the course of the 1st year as the
    nervous system becomes more integrated

19
One of the major body rhythms is an infants state
  • -- An infant's STATE is the degree of awareness
    it displays to both internal and external
    stimulation.
  • -- Includes various levels of wakeful behaviors
    (alertness, crying, etc.) and various levels of
    sleep (active, quiet)
  • -- Changes in state are reflected in brain waves
    measured by a device called an EEG, or
    electroencephalogram.

20
The major state occupying the infant is sleep.
  • On average, newborns sleep 16-17 hours daily,
    ranging from 10-20 hours a day.
  • Sleep stages are fitful and "out of sync" during
    early infancy.
  • By the end of the first year most infants are
    sleeping through the night.

21
The Infants Cycle of Sleep
  • Infants have a cycle of sleep similar to but
    different than REM - RAPID EYE MOVEMENT, (the
    period of sleep found in adults and children and
    is associated with dreaming).
  • Brain waves are different than the dreaming sleep
    of adults.
  • This active REM-like sleep takes up half an
    infants sleep at first.
  • Researchers think the function of REM sleep in
    infants is to provide a means for the brain to
    stimulate itself (autostimulation).

22
REM Sleep Through the Lifespan
REM sleep increases the total amount of sleep
falls as we age.
23
For a small of infants, the rhythm of sleep is
interrupted by a deadly occurrence SIDS
  • SUDDEN INFANT DEATH SYNDROME (SIDS) is a disorder
    in which seemingly healthy infants die in their
    sleep.
  • affects 7,000 children in U.S. annually
  • no cause found
  • The leading cause of death in children under 1
    year old
  • Boys, African-Americans, and low birthweight and
    low Apgar scorers, and babies whose mothers
    smoked during pregnancy are at higher risk.

24
Declining Rates of SIDS
US rates have dropped 38 since 1992 as parents
have learned to have babies sleep on their backs.
25
Motor Development
  • ? Basic REFLEXES, unlearned, organized,
    involuntary responses that occur automatically in
    the presence of certain stimuli, represent
    behavior that has survival value for the infant.
  • swimming reflex
  • eye blink reflex

26
More about reflexes in motor development
  • Some reflexes stay throughout life others
    disappear over time.
  • Some researchers believe reflexes stimulate the
    brain toward development.
  • Reflexes are genetically determined and universal
    and may be remnants from the past.
  • Reflexes can serve as helpful diagnostic tools
    for pediatricians because they appear and
    disappear on a regular timetable

27
Gross Motor Skills (rolling over, sitting
upright, walking)
  • By 6 months infants can move by themselves.
  • Most can sit unsupported by 6 months
  • Crawling appears between 8-10 months.
  • Infants can walk holding on to furniture by 9
    months and most can walk alone by 1 year.

28
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29
Fine Motor Skills (coordination, sophistication)
  • By 3 months infants can coordinate movements of
    limbs.
  • Infants can grasp an object by 11 months.
  • By age 2, infants can drink from a cup without
    spilling.

30
Milestones of Motor Development
50 of children are able to perform each skill at
the month indicated, but the specific timing
varies widely!
31
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32
  • It is important to keep in mind that
    developmental NORMS are the average performance
    of a large sample of individuals of a certain age
    and mask substantial individual differences!
  • (Norms are based on scales developed by
    developmental psychologists pediatricians)

33
A common technique to determine infants
normative standing
  • BRAZELTON NEONATAL BEHAVIORAL ASSESSMENT SCALE
    (NBAS)
  • NBAS is a measure used to determine infants'
    neurological and behavioral responses to their
    environment.
  • supplements the Apgar
  • 27 categories of responses
  • interactions with others
  • motor behavior
  • physiological control
  • response to stress

34
More about norms
  • Norms should be based on large, heterogeneous
    samples.
  • The time at which specific motor skills appear is
    in part determined by cultural factors.
  • There are certain genetic constraints on how
    early a skill can emerge

35
Nutrition in Infancy Fuels Motor
Development
  • Nutrition during infancy is extremely important!
    Without proper nutrition, infants cannot reach
    their physical potential and also may suffer
    cognitive and social consequences.

36
Underweight Children
In developing countries, the number of
underweight children under age 5 is substantial.
37
Malnutrition Its Effects
  • Malnutrition, the condition of having an improper
    amount and balance of nutrients produces several
    results.
  • --slower growth
  • --susceptibility to disease
  • --lower IQ scores

38
Malnutrition Its Effects, continued
  • --Malnutrition can also cause MARASMUS, a disease
    characterized by the cessation of growth in
    infants.
  • --Older children are susceptible to KWASHIORKOR,
    a disease in which a child's stomach, limbs, and
    face swell with water.

39
(malnutrition, continued)
  • Risks of malnutrition are greater in
    underdeveloped countries and in areas with high
    poverty rates.
  • Undernutrition is more common in developed
    countries (deficiency in the diet).

40
Children Living in Poverty
Single-parent and minority families are more
likely to have kids under age 3 living in
poverty.
41
For the first four to six months of life there is
no better food for an infant than breast milk!
Why?
Nutrition as Fuel for Motor Development Breast
or Bottle??
  • all essential nutrients
  • natural immunity to childhood diseases
  • more easily digested
  • health advantages for mother (lower cancer)
  • emotional advantages for both mother and child
  • bonding?
  • In spite of this, only half of mothers in U.S.
    breast-feed

42
Breast Milk Advantages
43
Introducing Solid Foods
  • ?Most babies can begin to eat solid foods at
    about 4-6 months.
  • Foods are introduced gradually.
  • Weaning, the cessation of breast-feeding, occurs
    on average in the U.S. at 3-4 months.
  • ?Experts recommend infants be breast-fed for 6-12
    months.

44
Development of the Senses
  • Infants come to understand the world around them
    through sensation perception
  • SENSATION is the stimulation and responsiveness
    of the sense organs.
  • PERCEPTION is the sorting out, interpretation,
    analysis, and integration of stimuli involving
    the sense organs and brain.

45
Visual Perception Seeing the World
  • Newborn infants cannot see beyond a distance of
    20 feet.
  • By 6 months, the average infant's vision is
    20/20.

46
(vision continued)
  • Binocular vision, the ability to combine both
    eyes' vision to see depth and motion is achieved
    at 14 weeks.
  • Gibson's "visual cliff" experiments showed that
    most infants between 6-14 months would not crawl
    over the apparent cliff .
  • The visual cliff experiment examines the depth
    perception of infants
  • We do not know how early this depth perception
    occurs in infancy.

47
(vision continued)
  • Infants show clear visual preferences that are
    present at birth
  • Infants prefer to look at patterns and complex
    stimuli.
  • Infants prefer to look at faces.
  • Minutes after birth they show a preference for
    certain colors, shapes, configurations
  • May support the existence of specialized brain
    cells (genetic influence on visual
    preferences)but environmental influences too!

48
Preferring Complexity
In a classic experiment, Robert Fantz found that
2- and 3-month-old infants preferred to look at
more complex stimuli.
49
Auditory Perception The World of Sound
  • It is clear that infants hear from the time they
    are bornand even before! (prenatally)
  • Infants are more sensitive than adults to high
    and low frequencies but not to the middle ranges.

50
Auditory Perception continued
  • Sound localization permits infants to discern
    direction from which a sound is emanating.
  • --This skill is poorer in infants than adults
    because of infants' smaller heads.
  • --It reaches adult level at 1 year.
  • --Infants can differentiate changes in melodies
    and sounds - a requirement for language - and
    their mother's voice from other voices

51
Smell and Taste in Infancy
  • Infants react to unpleasant tastes and smells
    from birth.
  • Newborns can detect their mother's smell, but
    only when breastfed.
  • Infants have an innate sweet tooth.

52
Sensitivity to Pain and Touch
  • Infants are born with the capacity to feel pain.
  • Touch is one of the most highly developed sensory
    systems in a newborn.
  • The rooting reflex is strong.
  • Infants gain information about the world through
    touch.
  • Even the youngest infants respond to gentle
    touches and are calmed by them

53
Effects of Massage Touch on Weight Gain
The weight gain of premature infants who were
systematically massaged is greater than those who
did not receive the massage!
(Field, 1988)
54
From research to practice
Knowing what we know about pain touch
  • Should Male Infants be Circumcised?
  • Jewish Islamic faiths this is a custom
  • American Academy of Pediatrics (2000) NO! Minor
    health benefits outweighed by risks.
  • -Risks infection, irritation, bleeding, reduced
    sexual pleasure
  • -Minor benefits slightly lower risk of urinary
    track infections
  • Cultural psychological issues involved in
    decision!

55
Initially, information is collected and
interpreted by individual sensory systems, but
  • Eventually infants use the MULTIMODAL APPROACH TO
    PERCEPTION in which information collected by
    various individual sensory systems is integrated
    and coordinated.
  • This approach is evidence of the sophisticated
    perceptual abilities of infants (combining
    sensory inputs!)

56
(MULTIMODAL APPROACH TO PERCEPTION, continued)
  • The infants growing perceptual ability is aided
    by the development of affordances (action
    possibilities connected to a situation or
    stimulus).
  • Example Julissa learns that her toy truck has
    several affordances It can be grabbed and
    squeezed, chewed, thrown across the room at the
    cat, etc.)

57
The Point
  • Infants perceptual abilities are increasing
  • Their physical development is advancing
  • They are developing senses that will serve as
    foundations of life!

58
Dont forget
  • Read Chapter 5 for next time
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