Transcript Document

Life Span Development
The First Two Years:
Biosocial Development – Chapter 5
Cognitive Development – Chapter 6
June 17, 2004
Class #4
Chapter 5:
Normal Growth and Development
A newborn infant loses approximately 5% to 10% of his
or her weight immediately after birth
 By 2 weeks of age, an infant should have regained the
lost weight and started to gain additional weight
 For the first 6 months of life, most infants will gain about
1 ounce per day and grow in length by about 1/3 to 1/2
an inch per week
 By the time an infant is 4 to 6 months old, his or her
birth weight will have doubled
 From 6 to 12 months old, the rate of weight gain slows
to about 1/2 an ounce per day.
 From 1 until 5 years old, weight gain will have slowed to
about 5 pounds per year and height will increase by 3 to
5 inches per year
 At this age, toddlers appear to lose their "baby fat" and
thin out
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Malnutrition
Undernutrition will result in delayed
growth
 An undernourished child:
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– Tires easily
– Possible short attention spans
– Learning problems
– Frequent illness and infections
Malnutrition
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Head-sparing
– Biological protection of the brain when
malnutrition temporarily affects body growth
A good breakfast is important…
Studies show that children at all ages
benefit from nutritious breakfast
 Tend to have better attention spans and
learn better than those that skip breakfast
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Breast milk is recommended…
Infants who are breast-fed contract fewer infections than
do those who are given formula
 Until fairly recently, most physicians presumed that
breast-fed children fared better simply because milk
supplied directly from the breast is free of bacteria
 Formula, which must often be mixed with water and
placed in bottles, can become contaminated easily
 Even infants who receive sterilized formula suffer from
more meningitis and infection of the gut, ear, respiratory
tract and urinary tract than do breast-fed youngsters
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Breast milk is recommended…
• Breast Milk
- begins with colostrum, high-calorie
nourishment before milk “lets down”
- easily digestible
- has antibodies and antibacterial properties
- better for baby’s health
• Bottle Feeding: babies more likely to have
allergies
- better option if mother is HIV-positive or
using drugs
Sleep
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Newborns sleep about 17 hours per day
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needed for rapid growth
REM sleep—rapid eye movement sleep—declines
quiet sleep increases at about 3 months
too immature to sleep through the night
Infant’s sleep patterns influenced by brain
waves and parents’ caregiving practices
First-borns are usually bad sleepers…
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As compared to their siblings…why?
Early Brain Development
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Most critical biosocial aspect of growth
– newborn’s skull disproportionately large
– at birth, 25% of adult brain weight
– by age 2, 75% of adult brain weight
Why are the heads of newborns so large
in relation to the rest of their bodies?
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Heads must be big enough to hold the
brain which is already 25% that of an
adult despite the fact that the rest of the
body is 5-10% of that of an adult
Another reason why most newborns
won’t win any beauty pageants…
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The average newborn has spent about 12
hours squeezing through the birth canal,
his head may be misshapen or kind of
pointy
– C-section babies, who don't travel the birth
canal, have an edge in the looks department
– Their heads don't get squeezed, so they come
out nice and round
Connections in the Brain
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Head measurement increases 35% in first
year
– Brain development: changes in the brain’s
communication system
– By age 2, the brain is 75% of an adult while the
rest of the body is about 25%
Basic Brain Structures
• Neurons—long thin nerve cells that
make up nervous system
- created before birth
- 70% in cortex (brain’s outer layer)
• Axons—nerve fibers that extend
from neurons that send impulses
• Dendrites—nerve fibers extending
from neurons that receive impulses
Basic Brain Structures
• Each neuron has a single axon (nerve
fiber) that extends from it and meets
the dendrites of other neurons at
intersections called synapses
- axons and dendrites don’t actually touch at
synapses
- electrical impulses trigger brain chemicals
called neurotransmitters, which carry
information from axon of sending neuron across
synaptic gap to dendrites of receiving neuron
- synapses are critical communication links with
the brain
Exuberance
• At birth more than 100 million
neurons are present
• Phenomenal growth is referred to as
transient exuberance—fivefold
increase in dendrites in first 2 years
• As many as 15,000 connections may be
made per neuron
Experience Enhances the Brain
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Specifics of brain structure and
growth depend partly on experience
– exuberance is transient—transitional
stage between newborn brain’s
immaturity and the maturity of older
child’s or adult’s brain
– underused neurons are inactivated, or
pruned
Experience Enhances the Brain
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Reactions to Stress
– experiencing stress may cause
overproduction of stress hormone
 developing brain can lose capacity to react
normally to stress
 normal neuron connections may have been pruned
for rapid response to repeated stress
Experience Enhances the Brain
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William Greenough identified 2
experience-related parts of brain growth
– experience-expectant brain functions
 require basic common experiences to develop
normally
– experience-dependent brain functions
 depend on particular and variable experiences to
develop
Greenough et al. (1987)
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Felt that "experience-expectant“ occurs because the nervous
system has been programmed by our genes to display an exuberant
growth of connections at particular points in time (e.g., eyeopening) in anticipation of experiences that are common to the
species
– Example:
 we are born with all of the circuitry necessary to learn any
language easily
 After birth, when we hear the language of our parents, we
prune away those parts of the circuit (i.e., synapses) that are
not necessary for the comprehension and production of that
language
In contrast, "experience-dependent" plasticity occurs in
adulthood in response to new or novel situations
– Plasticity in this case is manifested by smaller bursts of new
synaptic growth within a localized region of the brain that is then
pruned by the continuing experience
Experience Enhances the Brain
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Human brains are designed for expected
experiences
– how the brain is structured and connected will
depend on those experiences
– the brain expects certain experiences at
certain ages
 these experiences critical if connections are to form;
if connections not formed, plasticity may allow new
connections and pathways as experiences continue
Sensation and Perception
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All senses function at birth
– sensation—the response of sensory system
when it detects stimulus
 begins with outer organ—nose, eyes, etc.
– perception—mental procession of sensory
information when brain interprets sensation
 begins in the brain and requires experience
– cognition—thinking about what was perceived
The Competent Newborn
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Babies come equipped with several
reflexes suited for survival…
– The rooting reflex
 Babies open their mouths and root for a nipple
when someone touches their cheeks
Habituation
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This term refers to an infants decreased
responding with repeated stimulation
– New stimuli get attention when first presented
but the initial attraction wears off in time
– Response is weakened with familiarity
 Boredom?
Vision Capabilities of the Newborn
At birth, infant vision is limited by immaturities
in both the eye and brain
 Newborns estimated to have 20:300 eyesight.
 Infants look longest at what they see best:
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Large patterns with the most elements
The most movement
The clearest contours
The greatest amount of contrast
Other Senses of the Newborn
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At 2-3 days, newborns can hear soft
voices and notice differences between
tones
– Special attention paid to speech, especially
baby talk
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Certain smells and tastes are liked better
than others
– Within a few days, breast-fed babies prefer
scent of own mother to that of another
mother
Reflexes of the Newborn
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Babies show involuntary, unlearned
reactions, or reflexes, in the first weeks
and months after birth
– Swift, automatic movements in response to
external stimuli
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Examples of observed reflexes in infants:
– Grasping reflex
– Rooting reflex
– Sucking reflex
Motor Skills
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Most visible and dramatic body change of infancy
– Gross Motor Skills
 Involve large muscles and body movements
 crawling, creeping, walking
– Fine Motor Skills
 Small, finely tuned movements, especially of hands and fingers,
including
– successful grabbing
– Fingering, pointing, and holding
 grasping a moving object
 transferring objects from hand to hand
 adjusting reach
Development of Motor Skills
Immunization
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Process that stimulates body’s immune system
to defend against attack by a particular
contagious disease
– smallpox
– polio
– measles
Sudden Infant Death Syndrome
SIDS is the diagnosis given for the
sudden death of an infant under one year
of age that remains unexplained after a
complete investigation, which includes an
autopsy, examination of the death scene,
and review of the symptoms or illnesses
the infant had prior to dying and any other
pertinent medical history
 Because most cases of SIDS occur
when a baby is sleeping in a crib, SIDS is
also commonly known as crib death
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Sudden Infant Death Syndrome
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Mounting evidence suggests that some SIDS babies are
born with brain abnormalities that make them vulnerable
to sudden death during infancy
Studies of SIDS victims reveal that many SIDS infants
have abnormalities in the "arcuate nucleus," a portion of
the brain that is likely to be involved in controlling
breathing and waking during sleep
Babies born with defects in other portions of the brain or
body may also be more prone to a sudden death
These abnormalities may stem from prenatal exposure to
a toxic substance, or lack of a vital compound in the
prenatal environment, such as sufficient oxygen
Cigarette smoking during pregnancy, for example, can
reduce the amount of oxygen the fetus receives
Sudden Infant Death Syndrome
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There currently is no way of predicting
which newborns will succumb to SIDS;
however, there are a few measures parents
can take to lower the risk of their child
dying from SIDS…
– Always put your baby to sleep on their back
– Make sure your baby's head remains uncovered during
sleep
– Keep your baby in a smoke free environment, before
birth and after
Chapter 6:
Piaget’s Theory
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Child psychologist Jean Piaget (18961980) described the mechanism by which
the mind processes new information
– He said that a person understands whatever
information fits into their established view of
the world
– When information does not fit, the person
must reexamine and adjust their thinking to
accommodate the new information
Piaget’s Theory
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Building blocks of development:
– Schemas
 Mental images – how we organize past experiences
into a framework for understanding future experiences
 These are basic units of knowledge
– Assimilation
 Here children take in information about new objects
by using existing schemas that fit the new objects
– Accomodation
 Here a child tries a familiar schema on a new object –
realizes it cannot be made to fit the object and then
changes the schema so that it will fit
Piaget’s Theory
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Piaget described four stages of cognitive
development and relates them to a
person's ability to understand and
assimilate new information:
– Sensorimotor
– Preoperational
– Concrete
– Formal Operations
Sensorimotor
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Birth to about age 2:
– During this stage, children learn about
themselves and their environment through
motor and reflex actions…
 Thought derives from sensation and
movement
 The child learns that he/she is separate from
his/her environment and that aspects of the
environment -- their parents or favorite toy -continue to exist even though they may be
outside the reach of their senses (object
permanence)
 Teaching for a child in this stage should be
geared to the sensorimotor system
Sudden Drops
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Visual cliff measures depth perception,
which is based not on maturity level but
affordance
- depends on prior experience
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Object Constancy
- things remain what they are, despite changes
in perception or appearance
- boundaries of three-dimensional objects
Movement and People
Dynamic perception—1 of the 2 principles
explaining infant perception; namely, that
from birth perception is primed to focus on
movement and change
 2nd principle explaining infant perception is
that babies are fascinated by people
 Infants most interested in emotional
affordances of their caregivers
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Memory
Certain amount of experience and
maturation in order to process and
remember experiences
 In first year infants have great
difficulty storing new memories
 Older children often unable to describe
events that occurred when they were
younger
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Memory
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Very early memories possible if
– situation similar to real life
– motivation high
– special measures aid retrieval by acting as
reminders
A Little Older, A Little
More Memory
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After 6 months infants capable of
retaining information for longer periods
of time with less reminding
Deferred imitation apparent after end
of first year
By middle of the 2nd year, children
capable of remembering and reenacting
complex sequences
Language:
What Develops in Two Years?
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Most impressive intellectual
achievement of young child and also
of all humans
How quickly we progress…
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Between nine months and one year of age the
child usually begins to produce whole words…
– By about the age of 1 and a half we have a
vocabulary of about 50 to 100 words
– By age 3 we are using full sentences
– By age 4 we are nearing adult competence
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Carey (1978)
– Children between 1 and a half and 6 learn about nine
new words every day
– Almost one per waking hour
Stages of Language
Development
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First sounds infants make that resemble
speech are called babblings
– Pre-linguistic speech
– The first stepping stone to spoken language
 Early words are reduced to shorter, easier
forms…
– Babies use gestures, intonations, facial expressions,
and endless repetitions to help make themselves
understood
Stages of Language
Development
By 18-24 months, spoken vocabulary is up to
300 words
 Babies then begin to combine words into
sentences, which are telegraphic, two-word
utterances
 By age 3, children begin to create complex
sentences and ask questions
 By age 5, children have acquired most of the
grammatical rules of their native language
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Language Development
Errors
Early in the word-learning process,
children often make the following
mistakes:
 Overextension
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– Here, the child applies a word to a broader
class of objects or actions than in adult usage
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Underextension
– This it the exact opposite as the child has a
more narrow or limited usage of the word
Language Development Errors
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Overgeneralization
– The child often utilizes an overgeneralization of
grammar rules
 Example: the use of past tense (“ed”)
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Social Cues
– Children seem to spontaneously check where
speakers are looking when they utter new words and
then link the word to the object the speaker is looking
at
 Unfortunately, it appears that autistic children lack this ability
How Is Language Acquired?
Nativist linguistic theories hold that
children learn through their natural ability
to organize the laws of language, but
cannot fully utilize this talent without the
presence of other humans
 This does not mean, however, that the
child requires formal tutelage of any sort
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Hard-wired?
That’s what famous linguist Norm Chomsky
believes…
– Chomsky claims that children are born with
a hard-wired language acquisition
device in their brains
 They are born with the major principles
of language in place, and with some
parameters to set
 This is still a controversial view, and many
linguists and psychologists do not believe
language is as innate as Chomsky argues
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Infants are Taught
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Skinner’s reinforcement theory: quantity
and quality of talking to child affects rate
of language development (learned)
– parents are good instructors
– baby talk characterized by
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high pitch
simpler vocabulary
shorter sentence length
more questions and commands
repetition
Social Impulses Foster
Language
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Social-pragmatic—social reason for
language: to communicate
Infants seek to respond, which shows
their being social in nature— and thus
mutually dependent—by
- vocalizing
- babbling
- gesturing
- listening
- pointing
A Hybrid Theory
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Emergentist coalition—combination of
valid aspects of several theories
- cortex contains many language centers
- nature provides several paths to learning
language