1 of 18 carol k. sigelman, elizabeth a. rider life-span human development, 4th edition chapter 5:...

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Carol K. Sigelman, Elizabeth A. Rider

Life-Span Human Development, 4th Edition

Chapter 5: The Physical Self

Chapter 5

The Physical Self

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Plasticity: Responsive change to stimulation

• Lack of normal experiences

- Abnormal brain development

- Hubel & Weisel’s kittens

• Stimulating experiences key

• Plasticity greatest at critical period

- Late prenatal, early infancy

- Brain always responsive to stimulation

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Later Brain Development

• Brain grows post-birth

- Birth: 25% of adult weight

- Age 2: 75% of adult weight

- Age 5: 95% adult weight (full weight by 16)

- Mylenation through adolescence

- Dendritic growth (more synapses)

• Lateralization: 2 hemispheres (interdependent)

- Left: language, complex thought

- Right: spatial skills, visual motor, emotions

- Corpus callosum

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The Infant: Reflexes

• Survival: aid in survival

- Eye-blink

- Rooting

• Primitive: no clear use

- Babinski

- Stepping

- Forerunners of useful voluntary behavior

- Unrelated to later expression of behavior

- Fade in early months

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The Infant: Behavioral States

• Health = organized/unique pattern

• Sleep-wake pattern key

- By 6 mo: Sleep-wake patterns established

- Birth-6 months 50% sleep is REM

- Regulate sensory stimulation

- Growth (brain)

• Ability to learn

- Operant conditioning

- Sucking increases to sweet taste

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Growth in Infancy

• Fits and starts (no steady)

- First few months 1 ounce/day, I inch/month

- By age 2: About 1/4 adult height

- Inadequate nutrition = growth retardation

- Catch-up growth

• Principles of Growth

- Cephalocaudal: Head to feet

- Proximodistal: Center out

- Orthogenic: Undifferentiated to differentiated

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Motor Skills in Infancy

• Rhythmic stereotypies key

- Repetitive movements before, not after skill develops

• Dynamic systems approach

- Skills develop over time via self-organization process

- Sensory feedback to movements critical

- Nature (maturation) & Nurture (experience)

• Connected to perceptual-cognitive development

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Growth in Childhood

• Slows down, but is steady

- 2-3 inches height & 5-6 lbs/year

• Large and small muscle control improves

- Better coordination, movement

• Reaction time decreases

• Adaptation to a changing environment

- Hand-eye movements improve

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Adolescence

• Physical growth spurt

- Triggered by hormones

- Gender differences

- Earlier for girls

- Boys: more lean muscle, girls more fat

• Puberty (primary & secondary sexual characteristics)

- Gender differences

- Menarche (average 12.5 year)

- Semenarche (average 13)

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Figure 5.7a

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Figure 5.7b

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Variations in Timing (early & late development)

• Causes

- Genetic differences

- Environmental influences

- Secular trend

- Nutritional status

- Family stress

• Psychological implications

- Early easier for boys than girls

- Late easier for girls than boys

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Psychological implications

• Girls have poorer body images- Body fat, cultural myths contribute to negative body image for

many young women

• Boys have more positive views of their changing bodies- 62% view semenarche positively v. 23% girls & menarche

• Puberty often leads to increased independence, conflict

• Early v. late development (differences fade over time)- Early easier for boys than girls

- Girls can develop problematic behavior from older peers

- Late easier for girls than boys

- Boys tend to be more anxious, less confident/athletic

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Adolescent Physical Behavior

• Noticeable increases in strength

- Continues for boys

- Levels off for girls

• Biological differences: Advantages for boys

• Gender-role socialization

- If athletic, advantages for girls

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Adulthood

• Aging steady but not apparent before 40s

- Hair & skin changes, weight gain

• Weight and muscle loss in the 60’s

- Sedentary lifestyle

- Low education levels

• Osteoporosis: Calcium, exercise

• Osteoarthritis

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Adulthood: Functioning & health

• Physiological systems decline from 20s

- Wide individual differences

- Exercise combats decline

- Reserve capacity

• Changes not universal- Vast majority of older adults retain adequate function

- 70 or older: 88% men 82% women can walk 1/4 mile

- 92% men 88% women can climb 10 stairs w/o rest

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Adulthood: Functioning & health

• Menopause

- Gradual process taking 5-10 years

- Periods more/less frequent & less regular

- Estrogen levels decline

- Lack of ovulation and conception impossible

- Hot flashes key symptom (Psychological disturbance not common)

- HRT: many risks & benefits

• Male Climacteric gradual

- Levels of testosterone declines

- May never be completely infertile

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Aging:Psychological implications

• Ageism internalized

• Majority function independently

• Majority have high sense of well-being,

contentment

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Physical Behavior in Older Adults

• Slowing down

- Balance and strength decline

- Exercise beneficial

• Disease, disuse, and abuse

- Birren study of men age 65-91

- Increased vulnerability to disease

- Use it or lose it

- Abuse in lifestyle

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