Motivation – Hunger

Things to know - Motivation & Emotion: 1)Human motivation is complex, & while there are a number of theories, none by itself sufficiently explains our behavior. 1)Biological motivation includes the role of the hypothalamus, which maintains a state called homeostasis. 1)Theories of social motivation, including the need for achievement & hierarchy of needs, show the importance of understanding motivation in the context of our environments. 1)Emotions can be explained through a variety of theoretical perspectives, each arguing that emotion emerges in conjunction with physiological response to stimuli.

What Triggers Hunger? Physiology ● Homeostasis Set Point ● Hormones Insulin/Glucagon Ghrelin/Leptin ● Hypothalamus VMH (satiety) LH (hunger)

Copyright © Allyn & Bacon 2007 Hunger Eating comes naturally ▫ If it was entirely learned you would probably starve before learning it BIOLOGICAL MOTIVATION: Hypothalamus: region of brain most often associated w/ motivation Motivation: feeding, fighting, fleeing, & sexual reproduction. Physiology of Hunger Washburn: showed hunger partially related to the stomach. **However, those persons who have had their stomachs removed still feel hunger. Glucose: hormone insulin converts glucose to fat. When glucose levels drop: HUNGER INCREASES

The Physiology of Hunger Stomach contractions (pangs) send signals to the brain making us aware of our hunger.

Physiology of Hunger Washburn: showed hunger partially related to the stomach. **However, those persons who have had their stomachs removed still feel hunger. BIOLOGICAL MOTIVATION: Hypothalamus: region of brain most often associated w/ motivation Motivation: feeding, fighting, fleeing, & sexual reproduction. Glucose: hormone insulin converts glucose to fat. When glucose levels drop: HUNGER INCREASES

1960s: Discovered that hunger comes from the Brain. The Hypothalamus The Brain

Hypothalamic Centers Lateral hypothalamus (LH) brings on hunger. Destroy it and the animal will starve. Ventromedial hypothalamus (VMH) depresses hunger (stimulation). Destroy it and the animal eats excessively. Richard Howard

Summary of Hypothalamus & Hunger Along lower middle section of hypothalamus is the ventromedial hypothalamus: depresses hunger Stimulate the ventromedial hypothalamus & the animal will stop eating Lesion the ventromedial hypothalamus the animal will continuously want to eat. Along the sides of the hypothalamus is the lateral hypothalamus: which brings on hunger. Stimulate the lateral hypothalamus & even a well fed animal will begin to eat. Lesion the lateral hypothalamus & a starving animal will have no interest in food.

Biological Factors of Hunger 2. Basal Metabolic Rate: Each person burns food at a different rate & expends energy with different efficiency. A person with a high metabolic rate can eat more without gaining weight than someone who is just as active, but has a lower metabolic rate. 3. Body Set Point: Just as we have a temperature “thermostat” that keeps our body temp within an acceptable range, one theory suggests that we have a weight “set point.” Newer research suggests we have a “settling point” – a range of normal weights within which we can vary. 4. Taste sensation: Tastes is an important factor when we first begin eating. It encourages us to continue. 1. Activity of the lateral & medial hypothalamus.

Copyright © Allyn & Bacon 2007 Set Point Theory Hypothalamus acts as a thermostat. We are meant to be in a certain weight range. When we fall below weight our body will increase hunger & decrease energy expenditure (Basal Metabolic Rate) What happens if we go above our set point? Theory states we will auto correct to lower point.

Set-Point Theory Manipulating lateral and ventromedial hypothalamus alters the body’s “weight thermostat”…predisposing us to keep our bodies at a steady weight. If weight is lost (go below set point) – food intake increases and energy expenditure decreases. If weight is gained (go above set point) – the opposite takes place.

Set-Point Theory To maintain set point, the body not only adjusts food intake and energy output, it also adjusts its basal metabolic rate, the body’s resting rate of energy expenditure, dropping when less activity is occurring  Not all researchers believe in idea of a set point b/c believe that slow, sustained changes in body weight can change set point

The Psychology of Hunger External incentives… eat because triggered by the presence of food, especially tasty (high fat/calorie) food Eating by the “clock”… eat because it is “time” to eat lunch/dinner Social eating… eat at an event because you are “expected” to Stress and depression… eat more/less and different types of foods Other eating cues… holidays or watching TV/movie

Hunger Drive Hunger is probably the most researched of all physiological needs. Arises from a complex mixture of external and internal factors: External Factors Internal Factors Stress - A person may eat to counteract negative feelings produced by stress. (Stress- unpleasant, Eating pleasant) Certain foods release the neurotransmitter serotonin, which has a calming effect. Eating habits - Eating at fixed times of the day, regardless of hunger. Food-related cues - Eat because food is appealing to you, even though you are not hungry. Eating dessert even though you are full. Presence of eating cues - If you always have a snack an hour before going to bed, when the cock reaches that hour, it motivates you to go and get food - hungry or not. Hypothalamus - 2 factors, one monitors chemicals related to the amount of glucose in the body. When glucose drops, the hypothalamus produces sensation of hunger. After the need has been met, other chemicals are released that signal the feeling that you are full. A second homeostatic system measures the amount of fats and amino acids stored in the body's cells. When their levels drop too low, hunger signals are switched on. Basal Metabolic Rate - Each person burns food at a different rate and expends energy with different efficiency. A person with a high metabolic rate can eat more without gaining weight than someone who is just as active, but has a lower metabolic rate. Body (basal) Set Point - Falling below that "set point" of weight triggers biological processes that cause us to get hungry more often. Taste Sensation - Tastes is an important factor when we first begin eating. It encourages us to continue. Before long, the taste buds begin to shut down so that we are willing to stop eating when we are full.

Hunger & eating are governed in part by a variety of food-related cues. Schachter found that obese subjects would eat more than non-obese subjects when they were told it was much later in the afternoon than it actually was. Also, they would eat more of a tasty ice cream product than one that was not as tasty.

Taste Preference: Biology or Culture? Body chemistry and environmental factors together influence not only when we feel hunger but what we feel hungry for! Beijing street market fare

Eating Disorders Anorexia Nervosa: Characterized by a normal- weight person (usually adolescent women) losing (dramatic amounts) weight continuously and yet still feeling overweight. Reprinted by permission of The New England Journal of Medicine, 207, (Oct 5, 1932), Lisa O’Connor/ Zuma/ Corbis

Eating Disorders Bulimia Nervosa: A disorder characterized by episodes of overeating, usually of high- calorie foods, followed by vomiting, laxative use, fasting, or excessive exercise. Binge eating: recurrent binge eating without any type of “purging as in bulimia

Body Image (Women) Western culture tends to over-emphasize thin body image more than other cultures… Cultures who put more emphasis on appearance have higher rates of eating disorders

Summary of Hunger

Activities Motivational Music— connect music to motivational theories Maslow’s Hierarchy Handout— apply Maslow’s needs to your own. What helps you reach self- actualization?

NEXT CLASS No HOMEWORK tonight. We’re going to study “sex and belongingness” reading guide and activities in class. Next class: You’ll be assigned an activity on the computer. Then you and your family will need to fashion out how to study and learn about “sex and belongingness”