Motivation. simple, unlearned responses to specific stimuli -often mediated by direct connections in spinal cord

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Norma Bradford
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2 Motivation Why do people do the things they do? reflexes simple, unlearned responses to specific stimuli -often mediated by direct connections in spinal cord learned (conditioned) behaviors physiological needs drives increase likelihood of behavior cognition thoughts, beliefs and strategies about consciously directed behaviors that best satisfy drives What are the basic drives? Why are some things more motivating (reinforcing) than others?

3 regulatory Kinds of Drives primary biological maintenance survival regulated by homeostasis breathing, hunger, thirst, pain, sleep non-regulatory long-term maintenance sex, attachment, nurture, novelty, aggression long-term comfort self-esteem, power, achievement, self-actualization we ll come back to these in Ch. 15

4 Homeostatis homo (equal) + stasis (state) body s maintenance of a constant state e.g., body temperature, blood glucose, salts in bodily fluids, sympathetic vs. parasympathetic NS analogy: thermostat set point = optimal level Too little Just right Too much Too little Just right Too much Too little Just right Too much Stable internal state Deviation produces a drive e.g., too little food hunger Drive gives motivation to restore homeostasis e.g., hunger eating satiation

Hypothalamus hub for drive systems closely linked to the hippocampus (memory), amygdala (emotion), pituitary gland (releases hormones) and cerebral cortex

5 Hypothalamus hub for drive systems closely linked to the hippocampus (memory), amygdala (emotion), pituitary gland (releases hormones) and cerebral cortex (cognition) If I had to give up just a cubic millimeter of tissue from some part of my brain, the last place I would want it taken from is the hypothalamus. -- Peter Gray

6 example of a regulatory drive mediated by homeostatis clear biological basis with environmental influences

7 Lateral Hypothalamus hunger centre neural recording food conditioned stimulus associated with food stimulation eating lesions starvation

8 Ventromedial Hypothalamus satiation centre stimulation rats don t eat lesions rats become obese

9 Eat Increase in blood glucose above set point Accumulation of body fat above set point Inhibit LH Excite VMH Hunger Satiety Excite LH Inhibit VMH Decrease in blood glucose below set point Decrease in body fat below set point Stop Eating

10 Study this on your own Peter Gray FQ 6-10 esp. Fig. 6.4 Tuesday s Test Yourself question will be based on the various factors that control hunger

11 Twin Studies Optional refresher: Gray p. 58 Identical Twins monozygotic (MZ): originate from one zygote 1 zygote = 1 sperm + 1 egg 100% relatedness Fraternal Twins dizygotic (DZ): originate from two separate zygotes 50% relatedness same as any two siblings

12 Logic of Twin Studies Both identical and fraternal twins share the same environment (same age, same parents) Only MZ twins share exactly the same genes Concordance: both twins share the same trait Discordance: one twin has a trait that the other doesn t When we observe a trait exhibiting high concordance for MZ but not DZ twins, we can conclude the trait is strongly affected by genetics

13 Comparison of Concordance Rates Between MZ & DZ Twins TRAIT Blood type Eye color Mental retardation Measles Idiopathic epilepsy Schizophrenia Diabetes Identical allergy Tuberculosis MZ (%) DZ (%)

14 Adoption Studies Examine whether adopted children bear a greater resemblance to their biological parents and siblings or their adoptive parents and siblings Can suggest whether genes or environment play a greater role (nature vs. nurture)

15 Genetic Factors in Obesity Adoption Study (Sorensen et al., 1992) weight of adopted children is more correlated with biological parents than adoptive parents Twin Study (Bouchard et al., 1990) 12 pairs of identical male twins were given an extra 1000 calories per day above the amount required to maintain their initial weight The weight that an individual gained was very similar to the weight gained by his twin...and showed the same distribution on the body Change in weight (twin B) Change in weight (twin A)

Obesity may reflect a thrifty gene -- one

environments, it may be maladaptive in modern

16 Obesity may reflect a thrifty gene -- one that promotes efficient metabolism when feasts are few and famines frequent Although this gene may have been beneficial in other environments, it may be maladaptive in modern society where food is ample and encouraged Why Obesity?

17 Everybody s Dieting! lbs 220 lbs in 2 years

18 but who is losing weight? People who lost >10% of weight for > 1 year Wing & Hill cited in Globe & Mail, Dec. 31, 2005) 1 hour+ of brisk activity daily didn t eat out ate breakfast got feedback (i.e., regularly weighed themselves) were consistent through the week and year (didn t binge on weekends & Christmas) worked on stress management Popular diets few people lose big time e.g., 10% of dieters lost >10% of weight (Dansinger, 2005, JAMA) Weight Watchers is one of the better diets Average result: 3.2% of weight loss maintained for 2 years (Tsai & Wadden, 2005, Ann Intern Med) extreme diets such as the Atkins diet have more dropouts (50%) than moderate diets such as Weight Watchers (35%) (Dansinger, 2005, JAMA)

most gained < 40 lbs (expected: 170 lbs) eventually stopped gaining weight upon cessation, most returned to

19 Gaining & Losing Weight gaining/losing weight can be very difficult WWII studies male prisoners ate 7,000 calories per day for 6 mos. most gained < 40 lbs (expected: 170 lbs) eventually stopped gaining weight upon cessation, most returned to initial rate (except those with family history of obesity) semistarvation in non-military volunteers most men lost ~25% of body weight frequent psychological problems some men had problems losing > 10 lbs.

20 Dieting affects your set point Too little Set Point 150 lbs Too much Too little Set Point 150 lbs Too much Too little 150 lbs Set Point Too much 130 lbs 170 lbs 130 lbs 170 lbs 130 lbs 170 lbs Before dieting During dieting After dieting yo-yo dieting makes you gain weight long-term lifestyle changes and gradual weight loss much better than short-term diet blitzes eat less, exercise more being fit is more important than being thin

Eating Disorders Anorexia Nervosa signs refusal to maintain normal body weight (< 85% of expected weight) intense fear of gaining weight disturbed body image amenorrhea (missed at least 3 menstrual

21 Eating Disorders Anorexia Nervosa signs refusal to maintain normal body weight (< 85% of expected weight) intense fear of gaining weight disturbed body image amenorrhea (missed at least 3 menstrual periods) usually begins in adolescence in upper-class Caucasian girls 15-20% eventually die from the disorder Christy Henrich, Olympic gymnast, 11 months before her death in years old, 4 10, 60 pounds Bulimia Nervosa signs binge eating inappropriate behavior to prevent weight gain (vomiting, laxatives, fasting, excessive exercise) typically affects average and slightly overweight women also primarily upper-class Caucasian women but more common in men and minorities than anorexia seldom fatal but causes health problems

22 1. Which body for your sex would be your ideal? 2. Which body would the opposite sex find most attractive? 3. Which body is most typical the modern average in our society?

Cultural Ideals ideal female form has changed over time fertility goddess 30,000 years ago Rubens 1639 Kate Moss 1994 cultures tend to value what is rare and difficult

25 Cultural Ideals ideal female form has changed over time fertility goddess 30,000 years ago Rubens 1639 Kate Moss 1994 cultures tend to value what is rare and difficult to achieve in some developing countries in Africa, obesity is considered a sign of being upper class in most developed countries where food is ample, obesity is undesirable

26 The Ideal Female Over the Years

27 Special K ad Ironically, she s the one worried about her weight. Keep your expectations reasonable and stay healthy!

29 Sex Drive: Hormones androgens main class of male hormones testosterone differences in testosterone levels during development can determine sex differences primary sex characteristics (genitalia) secondary sex characteristics (e.g., body hair) brain development» different for gay men? related to sex drive in both sexes (but not as strongly in females) high testosterone correlated with higher rates of sexual activity estrogens main class of female hormones lead to breast development, widened hips and rounded body contours estrogen levels do not correlate well with sexual interest

30 Sex Drive: Other Factors Cultural influences education, religion, culture, peer attitudes more influential for women Situations more influential for women Genetics affects sexual orientation twin/adoption studies suggest genetic component to homosexuality evidence for genetic markers for homosexuality in men but not women

31 What do women want? Men who like children Older men Men with good social status Men with good financial prospects

men and women hired to approach strangers of the opposite sex on a college campus "I have been

32 What do men want? Physical attractiveness Sex, sex, sex In some cultures, chastity (Clark & Hatfield, 1989) Attractive men and women hired to approach strangers of the opposite sex on a college campus "I have been noticing you around campus. I find you very attractive." 1. "Would you go out with me tonight?" 2. "Would you come over to my apartment tonight?" 3. "Would you go to bed with me tonight?"

33 What do people look for in partners? Single female, aged 25, seeks well-educated, established male, aged 22-28, interested in long-term relationship and children. Must be kind, generous and dependable. Single male, aged 30, who likes having fun seeks slim attractive female, I m tall, handsome and athletic.

34 How would evolutionary biologists explain this pattern?

35 rats (Olds & Milner, 1950s) Pleasure Centre place an electrode in various brain structures bar pressing causes electrode stimulation at most locations no effect at a few locations (associated with hypothalamus or limbic system), rats would continuously press bar to receive self-stimulation e.g., > 7,000X/hour for many hours rats would choose self-stimulation over food and water even though they would become exhausted and die of starvation humans stimulation of certain sites (associated with limbic system) can be pleasurable in a sexual sort of way or a happy drunk way Could this type of reward be an all-purpose motivation/reward centre?

36 Dopamine and Reward many of the pleasure centres contain dopaminergic neurons dopamine is released during many rewarding activities (e.g., eating when you re hungry) dopamine agonists increase self-stimulation of pleasure centres dopamine antagonists decrease self-stimulation of pleasure centres many highly-addictive drugs (heroin, nicotine, cocaine) enhance dopamine

37 Video Clip: Pleasure Centre Cavanagh Psych1 Disk3 (4:53): Emotion: Pleasure What would it be like to be a human with an electrode in your pleasure centre? How much self-stimulation does it take before a rat becomes satiated? To what lengths will rats go to achieve selfstimulation? How could you measure this? What do addictive drugs have in common?

Motivation. Kinds of Drives. Why do people do the things they do? reflexes. learned (conditioned) behaviors. cognition. regulatory.

Motivation. Kinds of Drives. Why do people do the things they do? reflexes. learned (conditioned) behaviors. cognition. regulatory. Motivation Why do people do the things they do? reflexes simple, unlearned responses to specific stimuli -often mediated by direct connections in spinal cord learned (conditioned) behaviors physiological