Chapter 5 PHYSICAL DEVELOPMENT IN INFANCY 2013 The McGraw-Hill
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Cephalocaudal: The sequence in which the earliest growth always
occurs at the topthe headwith physical growth and feature
differentiation gradually working from top to bottom Proximodistal:
Growth starts at center of body and moves toward extremities
PATTERNS OF GROWTH
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FIGURE 5.1 - CHANGES IN PROPORTIONS OF THE HUMAN BODY DURING
GROWTH
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Average North American newborn is 20 inches and 7 pounds Weight
doubles at about 5 months; triples by first birthday Height
increase at least 50% in first year Average 2-year-old 26 to 32
pounds and 32 to 35 inches tall Growth rate considerably slower in
second year Growth appears continuous but actually occurs in spurts
HEIGHT AND WEIGHT
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brain is the command center of organism Extensive growth in utero
and infancy Brain of neonate weighs less than one pound By first
birthday, the brain triples in weight, reaching nearly 70% of adult
weight EEG shows brain activity spurt from 1 to 2 years of age
BRAIN DEVELOPMENT
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Forebrain: The region of the brain that is farthest from the spinal
cord and includes the cerebral cortex and several structures
beneath it Cerebral cortex: Tissue that covers the forebrain like a
wrinkled cap and includes two halves, or hemispheres
Lateralization: Specialization of function in one hemisphere of the
cerebral cortex or the other MAPPING THE BRAIN
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FIGURE 5.3 - THE HUMAN BRAINS HEMISPHERES
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ARE NEURONS? Basic unit of nervous system Receive and transmit
messages Neurons vary according to function and location, but all
contain Cell Body Dendrites Axon Neurotransmitters
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FIGURE 5.5 - THE NEURON
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DO NEURONS DEVELOP? As child matures Axons grow in length Dendrites
and axon terminals proliferate Connection networks become more
complex Myelin Makes messages more efficient Myelination occurs
with maturation Inhibition of myelination results in disease
Multiple sclerosis
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Blooming and pruning Synaptic overproduction peaks about 4 months
after birth Prefrontal cortex overproduction peaks about 3 year of
age Adult density achieved in adolescence Heredity and environment
affect timing BRAIN DEVELOPMENT
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FIGURE 5.6 - THE DEVELOPMENT OF DENDRITIC SPREADING
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FIGURE 5.7 - SYNAPTIC DENSITY IN THE HUMAN BRAIN FROM INFANCY TO
ADULTHOOD
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brain demonstrates both flexibility and resilience Neuroscientists
believe that what wires the brain is repeated experience
Neuroconstructivist view: Biological processes and environmental
conditions influence the brains development The brain has
plasticity and is context dependent Brain development is closely
linked with cognitive development EARLY EXPERIENCE AND THE
BRAIN
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Infants 0 to 2 years of age slept an average of 12.8 hours a day
With a range of 9.7 to 15.9 hours The most common infant
sleep-related problem reported by parents is nighttime waking
Infant nighttime waking problems have consistently been linked to
excessive parental involvement in sleep-related interactions with
their infant SLEEP
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eyes flutter beneath closed lids In non-REM sleep, this type of eye
movement does not occur and sleep is quieter REM (RAPID EYE
MOVEMENT) SLEEP
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FIGURE 5.10 - DEVELOPMENTAL CHANGES IN REM AND NON-REM SLEEP
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Culture and Sleeping Arrangements Sharing bed common in many
cultures Crib/separate room common in U.S. American Academy of
Pediatrics discourages co- sleeping because of stress and SIDS risk
SHARED SLEEPING
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Infant stops breathing, usually during night, and dies without
apparent cause Highest cause of infant death in U.S. Highest risk
is 2 to 4 months of age Prone position reduces risk Less common in
bedroom with fan and infant who sleeps with pacifier SUDDEN INFANT
DEATH SYNDROME (SIDS)
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Healthy infants need Loving, supportive feeding environment 50
calories per day per pound of weight Breast milk (natures food)
Gradual increase of chew-and-swallow More fruits and vegetables,
less junk food Demand feeding becoming more popular Poor dietary
patterns can cause overweight NUTRITION
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Breast milk Fewer gastrointestinal infections Lower respiratory
tract infections Reduces effects of asthma in first 3 months Reduce
risk of skin inflammation May lessen likelihood of obesity Lowers
risk of childhood and adult diabetes Less risk of experiencing SIDS
Claims of no link to allergy prevention Claims of no links to
childrens cognitive development and cardiovascular system BREAST
VERSUS BOTTLE FEEDING
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is lower incidence of breast cancer in women who breast feed their
infants Reduction in ovarian cancer in women who breast feed their
infants Small reduction in type 2 diabetes in women who breast feed
their infants EVALUATION OF BENEFITS FOR THE MOTHER
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2013 The McGraw-Hill Companies, Inc. All rights reserved. Early
weaning can cause deficiencies Infants can develop: Marasmus: A
wasting away of body tissues in the infants first year, caused by
severe protein-calorie deficiency Kwashiorkor: A condition caused
by a severe deficiency in protein in which the childs abdomen and
feet become swollen with water Usually appears between 1 to 3 years
of age MALNUTRITION IN INFANCY
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Immunization begins in infancy Accident prevention Increased
monitoring needed in infancy Most common accidents in infancy
Aspiration of foreign objects Suffocation Falls Poisoning Burns
Motor vehicle accidents HEALTH
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Dynamic systems theory: The perspective on motor development that
seeks to explain how motor skills are assembled for perceiving and
acting When infants are motivated to do something, they might
create a new motor behavior Mastering a motor skill requires the
infants active efforts to coordinate several components of the
skill DYNAMIC SYSTEMS THEORY
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Built-in reactions to stimuli that govern the newborns movements,
which are automatic and beyond the newborns control Rooting Sucking
Moro Babinski Grasping REFLEXES
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Milestones for large muscle activities Development of posture
Learning to walk First year milestones - walks easily Development
in second year Skilled and mobile: pull toys, climb stairs Natural
exercise: walk quickly, run stiffly GROSS MOTOR SKILLS
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FIGURE 5.16 - MILESTONES IN GROSS MOTOR DEVELOPMENT
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skills that involve finely tuned movements Finely tuned
(coordinated) movements Perceptual-motor coupling necessary Finger
dexterity (thumb and forefinger) Two types of grasps: Palmar and
Pincer Wrists and hands turn and rotate more Experience and
exercise have impact FINE MOTOR SKILLS
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SENSATION AND PERCEPTION Sensation: Stimulation of the sense
organs. Perception: Interpretation of that stimulation. Process of
integrating disjointed sensations into meaningful patterns through
perception Measuring Sensation/Perception
Habituation/Dishabituation Head movement indicates some vision
Visual preference method: Measuring the length of time they attend
to different stimuli Tracking - Applied to vision and hearing
Technology
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VISION Visual acuity at Birth Estimate of 20/600 Best see objects 7
to 9 inches from eyes Greatest gains in visual acuity between birth
and 6 months By about 3 to 5 years of age, approximate adult levels
Neonates have poor peripheral vision 30 degree angle; By 7 weeks
increases to 45 degrees; By 6 months of age, equal to adult (90
degrees) Able to track movement within one day of birth Preference
for moving objects
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VISION Visual accommodation Self-adjustments made by eye lens to
bring objects into focus Neonates show little or no visual
accommodation Focus on objects 7 to 9 inches away Convergence Does
not occur until 7 or 8 weeks Color perception At birth, cones are
less well developed than rods Fully mature around 3 months
(Distinguish between blue/green) By 4 months can distinguish
between similar colors/hues
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Figure 4.5 CONVERGENCE OF THE EYES
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LOOKING CHAMBER
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VISUAL PREFERENCES Preferences Moderately complex Movement Contour
Infants prefer faces Discriminate maternal and stranger faces
Prefer attractive faces Pay most attention to edges
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Preferences for Visual Stimuli in 2-Month-Olds
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MOVEMENTS OF 1- AND 2-MONTH-OLDS
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PERCEPTION Depth Perception Develops around 6 months (onset of
crawling) Research using the Visual Cliff Gibson and Walk (1960)
Heart-rate response to determine fear Relationship between crawling
and fear of heights Avoidance of the cliff and infants posture
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HEARING Fetuses respond to sound Can localize sound Startled by
loud noises Neonates respond to amplitude and pitch Show preference
for mothers voices Responsive to sounds and rhythms of speech
Capable of perceiving phonemes of other languages Show no
preference for specific languages
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HEARING DeCasper & Spence (1986) Newborns can remember and
prefer a story read by mom during the last 6 weeks of pregnancy.
Exposed to 3 hours of story.
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DEVELOPMENT OF HEARING By 1 month, infants perceive differences
between similar speech sounds By 3 months discriminate caregivers
voices Infants perceive most speech sounds present in world
languages By 10 to 12 months, lose capacity to discriminate sounds
not found in native language By 6 months, they can detect high
frequency sounds nearly as well as preschoolers. By 6 months, they
can appreciate distance.
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AND TASTE Smell Well-developed at birth Demonstrate aversion for
noxious and preference for pleasant odors Vanilla and Strawberry
Recognize familiar odors Recognize mom by 6 days Taste Sensitive to
different tastes Demonstrate facial expressions in response to
tastes Prefer sweet tastes
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FACIAL EXPRESSIONS ELICITED BY SWEET, SOUR, AND BITTER
SOLUTIONS
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2013 The McGraw-Hill Companies, Inc. All rights reserved. TOUCH
AND PAIN Touch Sensitive to touch Touch elicits many reflex
behaviors Pain Past belief that neonates are not sensitive to pain
Neonates not cognitively equipped to ruminate about pain
Conditionable distress when confronted with situation that
previously presented itself as painful