Nature vs. Nurture(via)

or

“Why we are who we are”

Dr. Swoap

Intro to Psychology

Fundamental QuestionHow are we shaped by both our heredity

and life history?

Behavior Genetics•Attempts to explain individual differences

–Twin studies (U of M) (see Fig. 6.3)–Adoption studies

Behavior Genetics

–Heritability: The proportion of variation among individuals that we can attribute to genes–Temperament and Personality: Were you born that way?

•Video Sci Amer #23 “Bringing up Monkey”

Evolutionary Psychology

•How does natural selection work with regards to behavior?

–Survival-oriented behavior is passed on

Evolutionary Psychology and sexual behavior

•Survey:–Question 1: A sunny afternoon on vacation… You are relaxing by the ocean. A person you don’t know, but whom you think is really good-looking, comes up to you and says: “I find you really attractive. I’d like to sleep with you tonight.” What would you do/say?

–Question 2: How often do you think about sex?

How often do you think about sex?

• Amidst the festivities of a grand party, a young guy notices a strikingly beautiful girl and is immediately obsessed….

• He approaches her and begins to flirt boldly…. She tries to deny him, but soon is flattered by his attention and finds him quite attractive…

Love in bloom

• By the time he departs the scene, with just a few kisses, these two have exchanged fewer than a hundred words; yet, both are swooning with sensations of falling, desperately, in love.

• All their mental processes – thinking, planning, goals,

feelings, and motivations – have been suddenly

transformed….these brains have been completely

gripped by this brief encounter.

Romantic feelings kindle rapidly….

• In the hours after this meeting, these two can not stop thinking about each other

• The intensity of desire is so strong that each would happily forego food, sleep, comfort, and all competing pleasures, simply to be in each other’s presence again

Shakespeare (1595) was dramatizing one of the normal tensions of adolescence and development of sexual motivations.

Longing, obsession, and desire…

SEX: Nature via Nurture

•Energizing and directing arousal

•Interplay of internal and external stimuli

•Internal: Hormones, brain structures, neurotransmitters, imagined stimuli

•External: Environmental and sociocultural factors

Environmental Influence

–Five ways we are shaped along with genes:

1. Prenatal environment2. Early experience3. Peer Influence4. Culture5. Gender influences

Keep in mind that our genes influence the nurture and experiences we seek. (My children and their temperaments influence my parenting.)

Environmental Influence

–Five ways we are shaped along with genes:

1. Prenatal environment influences?

2. Early experienceMultiple studies emphasize the importance of stimulating experience &/or touch: Both enhance brain development (as does physical activity)

Rosenzweig et al., 1972)

2. Early experience -- continued

Multiple studies emphasize the importance of stimulating experience &/or touch: Both enhance brain development (as does physical activity)

(massage therapy with preemies)

Environmental Influence

–Five ways we are shaped along with genes:

3. Peer influence factors? (e.g., man in elevator)

4. Culture–Examples?

• Food preferences, personal space, aggression/violent behavior• Obesity

–Cultural influences combined with a genetic predisposition to store fat

Obesity Trends* Among U.S. Adults

(*BMI 30, or ~ 30 lbs overweight for 5’4” woman)

*Go to CDC slide show on “Obesity trends”

BODY MASS

ENERGY IN ENERGY OUTIncrease in availability of high density foods(sugar/fat are cheap)

Increase in size

Decrease in cost

Decrease in work- related activities

Decrease in activity of daily living

Genetic predisposition to store fat

Nature via Nurture in Obesity

Nature via Nurture in Obesity

“Our jeans no longer fit our waist because our genes no longer fit our environment”

5. Gender Influences

Why are you a male/female? (Besides the obvious reasons…)Gender is a social category of being male or female.

Gender development starts early

Is it a boy or a girl???

Interactive model of Gender Development

Parentingstyle

Child’s traits & Biological factors

Socio-culturalfactors

Socialization and gender

• Differential gender socialization• Gender and culture

– (e.g., rites of passage, expected behaviors)