Transcript Life span chapter 3-1 File

Growth and Stability
Motor Development
The Development of the Senses
Growth and Stability
Height and Weight
Growth
Although the greatest
increase in height and
weight occurs during
the first year of life,
children continue to
grow throughout infancy
and toddlerhood.
Are there gender and ethnic differences in
infant weight and length?
Decreasing
Proportions
At birth, the head
represents onequarter of the
neonate’s body. By
adulthood, the head
is only one-eighth
the size of the body.
Why is the
neonate’s head so
large?
Principles of Growth
•
•
•
•
Cephalocaudal principle
Proximodistal principle
Principle of hierarchical integration
Principle of independence of systems
Can you give an example of each of these?
Nervous System and
Brain: Foundations of
Development
Nervous system
comprises the brain and
the nerves that extend
throughout the body.
Neurons are the basic
cells of the nervous
system.
The Neuron
Quick Check
Neurons
Dendrites
Axons
Neurotransmitters
Synapses
How great brains grow!
Birth:
– 100-200 billion neurons
– Relatively few neuron-neuron connections
During first two years:
– Billions of new connections established and
become more complex
NEURON NETWORKS
Over the first 2 years of life, networks of neurons become increasingly
complex and interconnected. Why are these connections important?
Source: From The Postnatal Development of the Human Cerebral Cortex, Vol I–VIII by Jesse
LeRoy Conel, Camevebridge, Mass.: Harvard University Press, Copyright © 1939, 1975 by
the President and Fellows of Harvard College.
Use it or lose it!
Synaptic pruning
• Involves elimination of unused
neurons
Myelin
• Includes fatty substance that
provides protection and speeds
transmission of nerve impulses
• Allows established neurons to build
more elaborate communication
networks with other neurons
• Development of nervous system
proceeds most effectively through
loss of cells
• Is an outgrowth of a glial cel.
Form and Function: Brain Growth
Neurons reposition themselves with growth,
becoming arranged by function
– Cerebral cortex
– Subcortical levels
Shaken Baby
This CAT scan shows
severe brain injury in an
infant suspected of
being abused by
caretaker shaking.
Source: Malung, Bilo, Kuba & van
Rijn, 2011.
Environmental Influences on Brain Development
Plasticity
Sensitive period
Do you know?
What are some cultural or subcultural
influences that might affect parents’
childrearing practices?
What do babies do all day?
Life Cycles of Infancy
Wake
Defecate
Sleep
Eat
Rhythms and States
Rhythms
– Repetitive, cyclical patterns of behavior
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
Sleep: Perchance
to Dream
Sleep is 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 3-2)
Infants sleep in spurts, often
making them out of sync with
the rest of the world.
Primary Behavioral States
Source: Adapted from Thoman & Whitney, 1990.
Primary Behavioral States
Source: Adapted from Thoman & Whitney, 1990.
REM Sleep
• Involves period of
active sleep
• Occurs when closed
eyes begin to move
in a back-and-forth
pattern
• Takes up around
one-half of infant
sleep
As we age, the proportion of REM sleep
increases as the proportion of non-REM
sleep declines. In addition, the total amount
of sleep falls as we get older.
Source: Adapted from Roffwarg, Muzio, &
Dement, 1966.
• May provide means
for brain to
stimulate itself
through
autostimulation
Do babies dream?
Did you find examples in the text that
suggest that cultural practices affect
infants’ sleep patterns?
SIDS
Sudden infant death syndrome
• Leading cause of death in children under 1 year of
age
• Back-to-sleep guidelines (AAP)
Hypotheses about cause
• Undiagnosed sleep disorders
• Suffocation
• Nutritional deficiencies
• Problems with reflexes
• Brainstem abnormalities
• Undiagnosed illness
Actual cause of SIDS remains elusive!
Declining Rates of SIDS
In the United States, SIDS rates have dropped dramatically as parents have
become more informed and put babies to sleep on their backs instead of their
stomachs.
Source: American SIDS Institute, based on data from the Center for Disease Control and
the National Center for Health Statistics, 2004.
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!
The major principles of growth are the
cephalocaudal principle, the proximodistal principle,
the principle of hierarchical integration, and the
principle of the independence of systems.
The development of the nervous system first entails
the development of billions of neurons and
interconnections among them. Later, the numbers of
both neurons and connections decrease as a result
of the infant’s experiences.
Infants integrate their individual behaviors by
developing rhythms—repetitive, cyclical patterns of
behavior.
The sleep of infants often comes in fits and starts
initially coming in spurts of about two hours,
followed by periods of wakefulness. Because of this,
infants are “out of sync” with the rest of the world,
for whom sleep comes at night and wakefulness
during the day.
The __________ principle states that growth begins
with the head and proceeds down to the rest of the
body; the __________ principle states that
development proceeds from the center of the
body outward.
a. cephalocaudal; proximodistal
b. proximodistal; cephalocaudal
c. hierarchical integration; independence of systems
d. independence of systems; hierarchical integration
The process of synaptic pruning allows established
neurons to build stronger networks and reduces
unnecessary neurons during the first 2 years of life.
• True
• False
Although brain development is largely genetically
predetermined, it is also susceptible to
environmental experiences; the ability of the brain to
be modifiable by the environment is called (a)
__________.
a. plasticity
b. synaptic pruning
c. sensitive period
d. critical period
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
Reflexes: Inborn Physical Skills
Reflexes:
• learned, organized involuntary
responses that occur automatically
in presence of certain stimuli
Why do reflexes come and go?
Some Basic Reflexes in Infants
Can you identify the approximate age of disappearance
and describe each of these reflexes?
• Rooting reflex
• Stepping reflex
• Swimming reflex
• Moro reflex
• Babinski reflex
• Startle reflex
• Eye-blink reflex
• Sucking reflex
HINT: Check Table 3-3!
• Gag reflex
Ethnic and Cultural Differences and Similarities in
Reflexes
Reflexes are:
– Genetically determined
– Universal
Cultural variations in ways displayed
– Example: Moro reflex
Serve as:
– Diagnostic tool
– Social function
– Survival function
Moro reflex
Rooting reflex
Startle reflex
INFANT REFLEXES
Motor Development
in Infancy
Gross motor skills
•
Young infants
accomplish some kinds
of movements.
Fine motor skills
•
As infants are
perfecting their gross
motor skills, such as
sitting upright and
walking, they are also
making advances in
their fine motor skills.
Milestones of Motor Development
Developmental Norms
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)
Cultural
Influences
• Norms are useful only
to the extent that they
are based on data from
a large, heterogeneous,
culturally diverse
sample of children.
Cultural influences affect the
rate of the development of
motor skills.
• Many of the norms are
based on groups of
infants who are
predominantly
Caucasian and from the
middle and upper
socioeconomic strata
Nutrition in Infancy
Fueling Motor Development
So what is a healthy caloric allotment for
infants?
• About 50 calories per day for each pound
of weight
• Most infants regulate caloric intake quite
effectively on their own
• If allowed consume as much they seem to
want and not pressured to eat more, they
will be healthy
Malnutrition
• More common in children living in many
developing countries
• Characterized by lower growth rate
• Chronically malnourished during infancy =
lower IQ score later
What might be some of the reasons that
malnourishment, which slows physical
growth, harms IQ scores and school
performance?
How might malnourishment affect education
in third-world countries?
When Malnutrition Is Severe
Marasmus
Kwashiorkor
Nonorganic Failure to Thrive
Sufficient
nutrition
Symptoms
Reversal
“A fat baby is a healthy baby”?
Is breast best?
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
• Among the Ache people of South
America, infants spend nearly all their time
in direct physical contact with mothers.
• Study found that differences between
cultures that restrict early motor
movement and Western cultures fade by
age six.
• Cultural factors help determine the time at
which specific motor skills appear.
Reflexes are universal, genetically acquired physical
behaviors.
Among the major reflexes are the rooting reflex, the
Moro reflex, and the startle reflex.
During infancy children reach a series of milestones
in their physical development on a fairly consistent
schedule, with some individual and cultural
variations.
Goss motor skills include rolling over, sitting, and
walking. Later, fine motor skills appear, such as
grasping.
Nutrition strongly affects physical development.
Without proper nutrition infants cannot reach their
physical potential, and may suffer cognitive and
social consequences as well.
The advantages of breast-feeding are numerous.
Behavior becomes integrated through the
development of ________, which are repetitive,
cyclical patterns of behaviors.
a. states
b. rhythms
c. REM sleep
d. reflexes
Which of the following is NOT one of the
consequences of malnutrition during infancy?
a. Malnourished children sleep, on average, 6 to 8
hours less than nonmalnourished children of the same
age.
b. Malnourished children show a slower growth rate by
the age of 6 months.
c. Malnourished children score lower on IQ tests
later in life.
d. Malnourished children have a lower height
and weight by age 2 than nonmalnourished
children.
Breastfeeding has been associated with enhanced
cognitive growth.
• True
• False
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
Learning the World
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
While an infant’s distant vision is 10 to
30 times poorer than the average
adult’s, the vision of newborns provides
the same degree of distance acuity as
the uncorrected vision of many adults
who wear eyeglasses or contact lenses.
Visual Cliff
• The “visual cliff”
experiment examines
the depth perception of
infants.
Depth perception is a
particularly useful ability,
helping babies acknowledge
heights and avoid falls.
• Most infants in the age
range of 6 to 14 months
cannot be coaxed to
cross the cliff,
apparently patterned
area drops several feet.
Infant Visual Preference
Preferences that are
present from birth
– Genetically
preprogrammed to
prefer particular kinds of
stimuli
Fantz
– 2- and 3-month-old
infants preferred to look
at more complex stimuli
than simple ones.
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 between groups of different
sounds
– React to changes in musical key and rhythm
– Can recognize many language-related sounds
Smell and Taste in
a Small World
Infants
– Well developed at birth
– Helps in recognition of
mother early in life
Infants
– Have innate sweet tooth
– Show facial disgust at
bitter tastes
– Develop preferences
based on what mother
ate during pregnancy
Infants’ sense of smell is so well
developed hey can distinguish their
mothers on the basis of smell alone.
Sensitivity to Pain and Touch
Pain
• Infants are born with the capacity to experience pain.
Signs
• Heartbeat increase, sweating, facial expressions of
discomfort, and change the intensity and tone of crying
when hurt
• Developmental progression in reactions
The Power of Touch
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 the infant’s sensory
systems are initially separate and that brain
development leads to increasing integration.
Which view is correct?
What can professionals do?
Persons who are born without the use of one sense
often develop unusual abilities in one or more other
senses.
What can health care professionals do to help
infants who are lacking in a particular sense?
Exercising Your Infant’s Body and Senses
• Attempts to accelerate physical and sensoryperceptual development yield little success
(yet).
• Infants need sufficient physical and sensory
stimulation.
Exercising Your
Infant’s Body and
Senses
• Carry a baby in
different positions.
• Let infants explore
their environment.
• Engage in “roughand-tumble’ play.
• Let infants touch their
food.
• Provide toys that
stimulate the senses
What are affordances?
Perceptible affordances
– Exist where information on actions that are
afforded are perceptible
– Are dependent on language, culture, context,
and experience and vary for different individuals
Infants’ sensory abilities are surprisingly well
developed at or shortly after birth. Their perceptions
help them explore and begin to make sense of the
world.
Very early, 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 pain and touch, and most
medical authorities now subscribe to procedures,
including anesthesia, that minimize infants’ pain.
The multimodal approach to perception considers
how information that is collected by individual
sensory systems is integrated and coordinated.
______________ is the physical stimulation of
the sense organs.
a. Perception
b. Crying
c. Crawling
d. Sensation
We know that infants experience pain because
their heartbeat increases, they sweat, they show
discomfort, and their crying changes tone.
• True
• False
The ______________ considers how information
that is collected by various individual sensory
systems is integrated and coordinated.
a. multimodal approach to perception
b. affordance theory
c. multidisciplinary motor development cycle
d. macrosystem
If you were selecting a mobile as a gift for a young
infant, what features would you look for to make the
mobile as interesting as possible for the baby?