How does motivation direct and energize behavior?

1. How does motivation direct and energize behavior? Variety of approaches in psychology

2. Instinct approaches Channels behavior in appropriate direction Instincts Energy

3. Instinct approach • Behavior “hard-wired” into the nervous system • Provide survival value • More common in lower animals • Doesn’t meet the complexity of most human behavior • Modified by experience

4. Drive reduction approach • Satisfying our needs • Primary drives for Biological needs • Examples: hunger and thrist • Secondary drives based on prior experience • Examples: achievement and belongingness

5. Drive reduction • Strengths: • Primary drives satisfied • Homeostasis for bio needs • Weaknesses: • Humans and other animals seek new experiences

6. Drive reduction doesn’t explain • Curiosity • Sensation seeking • Animals want to increase level of arousal • Exploration • Risk taking

7. Motivation’s “pull” Behavior not always motivated internally External motivation Incentives Incentive approaches

8. Drive reduction “push” 5 hours since last meal hunger Incentive theory “pull” Ice cream truck Palatability (good tasting) Contrasting approaches

9. What are biological and social factors that underlie hunger?

10. Biological and Social • Biological: based on primary drive • Social: preferences heavily influenced by experience and culture • Ex: Grasshoppers and Worms in tacos • Ok in Mexico • Not Ok at Taco Bell in New Britain

11. Primary drive • Internal mechanisms regulate the quantity of food intake • And kinds of food desired • Animals given the choice of wide variety of foods • Choose a fairly well-balanced diet • Very rarely gain weight (except pets)

12. Biological factors • Chemical composition of blood (glucose) • Factor in controlling eating • Monitored by hypothalamus • On and off switches

13. Hypothalamus as monitor • Acts like thermostat in heating system • Heat comes on • Reaches temperature • Heat shuts off • Negative feedback loop

14. Damage lateral hypothalamus (LH) Animal refuses to eat LH may act as “on” switch Hunger sensor Damage ventromedial hypothalamus (VMH) Animal eats too much VMH may act as “off” switch Satiation sensor Hunger switches

15. VMH rat • 400% wt increase • Finicky • Prefer good tasting food (palatable) • Not willing to work for food • Make great house guests

16. Human weight regulation • Weight set point a key factor • Particular level of weight the body strives to maintain

17. Changing set point Food consumption increases Raise set point Lower set point Food consumption decreases

18. Set point and genetics • High metabolic rate • Eat without gaining wt • Low metabolic rate • Gain wt easily

19. Other factors which affect eating • Meals by the clock • Meal size unrelated to energy expended • Highly palatable foods may be high in calories • Eat for emotional or social reasons

20. Theory 1: External cues and obesity Oversensitivity to external cues Based on social convention (Sight, availability, time of day) Obesity Insensitivity to internal cues (stomach contractions)

21. Ignoring internal cues • Stanley Schacter • Early work by Stunkard • Subjects swallow gastric balloon • Balloon registers stomach contractions • Normal wt subjects reported hunger when stomach contracted • Obese subject paid little attention to internal cues

22. Govern eating by external cues • Palatability • Subjects given either “decent” vanilla shake or one spiked with bitter quinine • decent bitter • Normal 10 oz 6 oz • Obese 14 oz 3 oz Average amount of shake consumed

23. Availability • Have to work to get food • Bag of almonds on desk while waiting • How many subjects ate almonds • with shells without shells • Normal 10/20 11/20 • Obese 1/20 19/20

24. Other external cues • Eat by the clock • Sight of other people eating • Social settings

25. Why oversentive? • Schacter: oversensitivity to external cues causes overeating • Richard Nisbett (grad student with Schacter): • Just the reverse • Overeating causes increase in sensitivity • Overeating alters body’s set point for weight

26. Theory 2: Set point Eat more to feel satisfied Higher set point Obese Person If eat less, become very sensitive to external cues

27. Set Point theory • Set Point -------

28. Gaining weight • Increase in body weight • Increase in # and size of fat cells • Raises set point

29. Losing weight • Any loss of weight after age of two • No decrease in # of fat cells • Decrease in size • Weight set point doesn’t drop • Lowest possible weight gets “stuck”

30. Restrained eaters • Fighting to loose weight • Body sending out starvation signals • Can hold themselves back (restrain) • Stay on strict diet • Give in to desire to eat • Likely to binge

31. Yo-Yo effect • 95 % of wt lost is regained within a year • Some dieters put on more wt than lost • Famine hypothesis • Fat cells “think” there must be a famine while dieting • Rebound when person stops diet to help body survive the next “famine”

32. Theory 3: Settling point • Rapid rise in obesity in USA • 10% population in 1980, 31% in 1991 • Settling point: combo of genetics and the environment we live in • Cultural differences in diet • Americans versus Asians • Fast food nation

33. Advice from weight loss experts • There is no easy route to wt loss • Permanent changes in your lifestyle • Set reasonable goals • Exercise: critical factor in long run • Avoid fad diets • Don’t feel guilty