Chapter 5 The Physical Self

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

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

The Aging Brain Normal aging Brain weight decreases Gradual, mild degeneration Not senility Brain weight decreases Plasticity throughout lifespan Individual variation

The Infant: Reflexes Survival: aid in survival Primitive: no clear use Eye-blink Rooting Primitive: no clear use Babinski Stepping Forerunners of useful voluntary behavior Unrelated to later expression of behavior Fade in early months

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

Growth in Infancy Fits and starts (no steady) Principles of Growth 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

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

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

Adolescence Physical growth spurt Triggered by hormones Gender differences Earlier for girls Boys: more lean muscle, girls more fat Puberty (primary & secondary sexual characteristics) Menarche (average 12.5 year) Semenarche (average 13)

Figure 5.7a

Figure 5.7b

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

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

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

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

Physiological systems decline from 20s 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

Male Climacteric gradual 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

Aging:Psychological implications Ageism internalized Majority function independently Majority have high sense of well-being, contentment

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