5
Children
Physical Development
In Infancy
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How Do Infants Grow and Develop Physically?
Patterns of Growth
• Cephalocaudal: size, weight, and feature
differentiation gradually work from top to
bottom
• Proximodistal: growth starts at center of
body and moves toward extremities
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How Do Infants Grow and Develop Physically?
Changes in Proportions of
the Human Body During Growth
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How Do Infants Grow and Develop Physically?
Height and Weight
• Average North American newborn is 20
inches and 7½ pounds
– Birth weight doubles by 4 mos; triples at end of
first year; First year growth averages 1 inch per
month
– 1½ times birth length at end of 1st year
• Average 2-year-old
– 26 to 32 pounds and 32 to 35 inches tall
– Growth rate considerably slower in second year
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How Do Infants Grow and Develop Physically?
Brain Development
• Extensive growth in utero and infancy
• Shaken baby syndrome: brain swelling
and hemorrhaging
• PET and MRI scans may harm infant
• EEG shows brain activity spurt from 1½ to
2 years of age
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How Do Infants Grow and Develop Physically?
The Human Brain’s Hemispheres
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How Do Infants Grow and Develop Physically?
The Brain’s Four Lobes
(body sensations)
(voluntary
movement
and thinking)
Prefrontal
cortex
(vision)
(hearing)
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How Do Infants Grow and Develop Physically?
Brain Development
• Neuron: info processing nerve cell
– Axons and dendrites
• Myelin sheath: layer of fat cells
– Encases and insulates most axons
– Myelination continues into adolescence
• Synapses: tiny gaps
– Neurotransmitters
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How Do Infants Grow and Develop Physically?
The Development of Dendrite Spreading
At birth
1 month
3 months
15 months
24 months
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How Do Infants Grow and Develop Physically?
Brain Development
• “Blooming” and “pruning”
• Synaptic overproduction peaks about 4
months after birth
• Prefrontal cortex overproduction peaks
about 1 year of age
– Adult density achieved in adolescence
– Heredity and environment affect timing
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How Do Infants Grow and Develop Physically?
Synaptic Density in Human Brain from Infancy to Adulthood
70
60
Synaptic density
50
40
30
20
10
0
100
200
300
400
500
600
800
1000
1500
2000
3000
4000
6000
8000 10,000
Age in©days
(from
conception)
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McGraw-Hill
Companies, Inc. All rights reserved.
How Do Infants Grow and Develop Physically?
Early Experience and the Brain
• Environmental experiences important
• Infant’s brain waiting for experiences
• Early experiences and enriched environment
• Brain heavier in weight with thicker layers
• Brain develops more neural connections
• Produces higher neurochemical activity
– Impoverished environment
• Depression is common
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How Do Infants Grow and Develop Physically?
Sleep
• Newborn
– Sleep varies from 10 to 21 hours each day
– Preferred sleep times and patterns vary
– 20% to 30% have sleep difficulties
• Culture affects sleep patterns
– Length of sleep periods related to sleeping
arrangements and parental activities
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How Do Infants Grow and Develop Physically?
Sleep
• Regulation of wake-sleep cycle reflects
neurological maturation; cycles vary
• REM (Rapid Eye Movement) sleep
– Adults—fifth of sleep
– Infants—half of sleep
– May promote brain’s development in infancy
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Sleep Across the Human Life Span
24
16
Total daily sleep (hours)
14
12
10
8
6
4
2
0
1-15
days
Newborn
6
mo
12
mo
18
mo
Infants
2
yrs
10
yrs
20
yrs
Children Adolescents
30
yrs
Adults
40
yrs
50
yrs
60
yrs
70
yrs
80
yrs
Older adults
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90
yrs
How Do Infants Grow and Develop Physically?
Shared Sleeping
• 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
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How Do Infants Grow and Develop Physically?
Sudden Infant Death Syndrome (SIDS)
• 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
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How Do Infants Grow and Develop Physically?
Sudden Infant Death Syndrome (SIDS)
• Highest risks
–
–
–
–
–
–
–
–
Lower birth weight
Siblings with SIDS
Sleep apnea
Lower SES groups
Exposure to cigarette smoke
Placement in soft bedding
Abnormal brain stem functioning
African American and Inuit infants
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How Do Infants Grow and Develop Physically?
Nutrition
• Healthy infants need
–
–
–
–
–
–
–
Loving, supportive feeding environment
50 calories per day per pound of weight
Breast milk (nature’s 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
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How Do Infants Grow and Develop Physically?
Breast Versus Bottle Feeding
• 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
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How Do Infants Grow and Develop Physically?
Malnutrition in Infancy
• Early weaning can cause deficiencies
• Infants can develop
– Marasmus: wasting away of body tissues in
infant’s first year, severe lack of protein
– Kwashiorkor: deficiency in protein; child’s
abdomen, feet become swollen with water
– If not fatal, effects are detrimental; lowest SES
aided most by supplementary feeding
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How Do Infants Grow and Develop Physically?
Health
• Immunization begins in infancy
• Accident prevention
–
–
–
–
–
Increased monitoring needed in infancy
Asphyxiation: leading cause of death under 1
Choking hazards: toys, chunky foods
Burn risks: sun, electrical, heaters, hot water
Other risks: car accidents, cuts, pet bites
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How Do Infants Grow and Develop Physically?
Caring for Children
• Healthy Start Program – Hawaii
– Home visits for families: newborns to age 5
– Unstable homes and poverty:
• Substance abuse
• Parental depression, low education,
unemployment
• Child abuse
– Professional/medical support staff available
– Effective results
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How Do Infants Develop Motor Skills?
Dynamic Systems Theory
• Gesell revealed motor skill development
– Maturation: unfolding genetic plan
• Later studies: milestones not fixed
• Perceptions and motivation lead to new
motor skills or fine tuning
– Nervous system maturation
– Repeated “cycles” of actions
– Nature, nurture, and environment interact
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How Do Infants Develop Motor Skills?
Reflexes
• Built-in reactions to stimuli
– Rooting: reaction to cheek/mouth touched
– Sucking: automatic sucking object in mouth
– Moro reflex: startle response causes back
arching, rapid closing of arms and legs
– Babinski reflex: toes fan, foot arches when sole
is stroked
– Grasping: when something touches palm
– Some evolve into more complex actions
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How Do Infants Develop Motor Skills?
Gross Motor Skills
• Milestones for large muscle activities
– Development of posture
– Learning to walk; locomotion, balance, and
practice (crawling to walking)
– Adapting to slopes
– First year milestones: walks easily
– Development in second year
• Skilled and mobile: pull toys, climb stairs
• Natural exercise: walk quickly, run stiffly
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How Do Infants Develop Motor Skills?
Milestones in Gross Motor Development
© 2010 The McGraw-Hill Companies, Inc. All rights reserved.
How Do Infants Develop Motor Skills?
Cultural Variations in Guiding Infants’
Motor Development
• Infants reach motor milestones in different
cultures based on activity opportunities
– Variations not large
– Milestones reached within normal age ranges
– Algonquin of Canada
• Cradle boards
– Jamaica
• Baby massages and limb stretching
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How Do Infants Develop Motor Skills?
Fine Motor Skills
• 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
© 2010 The McGraw-Hill Companies, Inc. All rights reserved.
Infants’ Sensory and Perceptual Development
What Are Sensation and Perception?
• Sensation
– Occurs when information contacts sensory
receptors – eyes, ears, tongue, nostrils, and
skin
• Perception
– Interpretation of sensation
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Infants’ Sensory and Perceptual Development
The Ecological View
• People directly perceive information in the
world around them
– Perception allows human-environmental
interaction and adaptation
– Affordances: opportunities for interaction
offered by objects; enhanced by previous
experiences
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Infants’ Sensory and Perceptual Development
Studying Infant Perception
• Head movement indicates some vision
– Visual preference method: Fantz measured
length of gaze and patterns of preference in
“looking chamber”
• Habituation: decreased responsiveness
• Dishabituation: recover habituated response
• Tracking: applied to vision and hearing
– High-amplitude sucking, videos, computers
© 2010 The McGraw-Hill Companies, Inc. All rights reserved.
Infants’ Sensory and Perceptual Development
Visual Perception
•
•
•
•
Visual acuity and color in newborn
Perceiving patterns – patterns preferred
Perceptual constancy – size, shape
Depth perception
– ‘Visual cliff’ study and visual expectations
– Binocular cues by age 3 to 4 months
• Vision: influenced by nature and nurture
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Infants’ Sensory and Perceptual Development
Other Senses
• Hearing: begins in womb
– Infancy changes: volume, pitch, localization
•
•
•
•
•
Touch and Pain
Smell: present shortly after birth
Taste: may exist before birth
Intermodal perception: exists in newborns
Perceptual motor coupling
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5
The End
© 2010 The McGraw-Hill Companies, Inc. All rights reserved.