Psych 320: Motivation Eating & Drinking Behavior By the end of this lecture, you should be able to answer the following questions: 1 Be able to discuss the general homeostatic process in the motivations of ? hunger ? and ? thirst ? 2 Describe the Arnold studies of garter snakes that pointed to a genetic influence on eating behavior 3 Discuss some of the neural bases (such as the lateral hypothalamus) for eating and drinking behavior 4 What role does the subfornical organ play in drinking behavior? 5 Describe the methods and results of Blass & Hall (1976) on the inhibitory system in eating and drinking behavior 6 Be able to discuss the methods and results of the Galef studies on social learning of food preferences in rats 1. General Homeostatic Process-- food THIRST HUNGER Breakdown of glucose is what provides the energy for body to do work. Energy Intake (I)---Available fuel---Energy output/work (O) If (I) < (O), WE ARE HUNGRY= engage in eating behavior If (I) > (O), stop eating We can store food in the terms of fat (energy bank) 2. Internal Factors Evidence of instinctive preferences for salt and sweet foods why? Importance of salt/sugar rich foods This preference now detrimental? Instinctive avoidance of sour & bitter food why? Often indicates rotton or toxic foods Helps to avoid things that are generally toxic and can make you sick Idea of ? instinctive ? behavior criticized, but notion of genetic influences remains Garter snake prey item preferences à Work of Stevan Arnold · Garter snake prey item preferences · coastal snakes eat slugs, Inland snakes eat fish & frogs · Raise young in the same laboratory setting, test their food preferences · young costals--slugs · young inlands--avoid slugs Neurophysiological factors -lateral hypothalamus -regulation of salt intake -lesions of lateral hypothalamus=loss of salt appetite Neural Bases -Intracellular water -saline injection-lateral hypothalamus active...increased drinking--decreased lateral hypothalamus firing. -Extracellular water-losing water from body very quickly (injury=loss of blood, sickness=vomitting etc.) -dehydration -angiotensin produced by liver+kidneys -receptors on subfornical organ detect angiostensin levels--drinking -damage to the SFO=diminished drinking in presence of angiotensin Lateral Hypothalamus ? important roles in regulating salt and water intake Levels of glucose and fatty acids in cells (if too little, we are hungry) -Use of chemical blockers for glucose and fatty acids--they remain in bloodstream, individual eats, yet still is hungry 3. Inhibition Studies of eating inhibition à Blass and Hall (1976) -Rats given fistulas (common agricultural research method for cattle production: connects stomach to outside world) -testing food processing system one part at a time -result: stomach and intestines can detect when enough food is eat, but mouth is less accurate as a sensor of food intake 4. External Factors -Eating and drinking often in social context -social influences are linked to learning -social learning/cultural transmission -ex: Social transmission of food preferences in Norway rats à Work of Jeff Galef -method on blackboard Importance of culture to eating Many cases of cultural influences on food types, preferences, eating habits, etc. -culture and what we eat -culture and how much we eat? -The 'French' Paradox -Rozin et al. (2003 Psychological Science) -portion size in U.S. & French restaurants (table on blackboard) -assumption? -U.S. portion size is larger -given larger portions, people actually eat more -Geier et al. (2006 Psychological Science) -large vs small portions of food and amount taken (table on blackboard) -large portion=take more, eat more -small portion=take less, eat less Food prohibitions/constraints -Ramadan, Lent (examples: when and what kinds of things) -parents and active teaching of food preference -social and physical enviroment (vending machinces, advertising)
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