PSYCHOLOGY (9th Edition) David Myers PowerPoint Slides Aneeq Ahmad Henderson State University Worth Publishers, © 2010

Motivation and Work Chapter 11

Hunger  The Physiology of Hunger  The Psychology of Hunger  Obesity and Weight Control

Hunger When are we hungry? When do we eat? When there is no food in our stomach. When we are hungry. How do we know when our stomach is empty? Our stomach growls. These are also called hunger pangs.

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

Stomachs Removed Tsang (1938) removed rat stomachs, connected the esophagus to the small intestines, and the rats still felt hungry (and ate food).

Body Chemistry & the Brain Levels of glucose in the blood are monitored by receptors (neurons) in the stomach, liver, and intestines. They send signals to the hypothalamus in the brain. Rat Hypothalamus

Hypothalamic Centers The lateral hypothalamus (LH) brings on hunger (stimulation). Destroy the LH, and the animal has no interest in eating. The reduction of blood glucose stimulates orexin in the LH, which leads rats to eat ravenously.

Hypothalamic Centers The ventromedial hypothalamus (VMH) depresses hunger (stimulation). Destroy the VMH, and the animal eats excessively. Richard Howard

Hypothalamus & Hormones The hypothalamus monitors a number of hormones that are related to hunger. HormoneTissueResponse Orexin increaseHypothalamusIncreases hunger Ghrelin increaseStomachIncreases hunger Insulin increasePancreasIncreases hunger Leptin increaseFat cellsDecreases hunger PPY increaseDigestive tractDecreases hunger

Set Point Manipulating the lateral and the ventromedial hypothalamus alters the body’s “weight thermostat.” Heredity influences set point and body type. If weight is lost, food intake increases and energy expenditure decreases. If weight is gained, the opposite takes place.

The Psychology of Hunger Memory plays an important role in hunger. Due to difficulties with retention, amnesia patients eat frequently if given food (Rozin et al., 1998).

Taste Preference: Biology or Culture? Body chemistry and environmental factors influence not only when we feel hunger but what we feel hungry for! Richard Olsenius/ Black Star Victor Englebert

Hot Cultures like Hot Spices Countries with hot climates use more bacteria- inhibiting spices in meat dishes.

Eating Disorders Anorexia Nervosa: A condition in which a normal-weight person (usually an adolescent woman) continuously loses weight but still feels 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 high-calorie foods, followed by vomiting, using laxatives, fasting, or excessive exercise.

Reasons for Eating Disorders 1.Sexual Abuse: Childhood sexual abuse does not cause eating disorders. 2.Family: Younger generations develop eating disorders when raised in families in which weight is an excessive concern. 3.Genetics: Twin studies show that eating disorders are more likely to occur in identical twins rather than fraternal twins.

Obesity and Weight Control Fat is an ideal form of stored energy and is readily available. In times of famine, an overweight body was a sign of affluence.

Obesity A disorder characterized by being excessively overweight. Obesity increases the risk for health issues like cardiovascular diseases, diabetes, hypertension, arthritis, and back problems.

Body Mass Index (BMI) Obesity in children increases their risk of diabetes, high blood pressure, heart disease, gallstones, arthritis, and certain types of cancer, thus shortening their life- expectancy.

Obesity and Mortality The death rate is high among very overweight men.

Social Effects of Obesity When women applicants were made to look overweight, subjects were less willing to hire them.

Physiology of Obesity Fat Cells: There are billion fat cells in the body. These cells can increase in size (2-3 times their normal size) and number (75 billion) in an obese individual (Sjöstrum, 1980).

Set Point and Metabolism When reduced from 3,500 calories to 450 calories, weight loss was a minimal 6% and the metabolic rate a mere 15%. The obese defend their weight by conserving energy.

The Genetic Factor Identical twin studies reveal that body weight has a genetic basis. The obese mouse on the left has a defective gene for the hormone leptin. The mouse on the right sheds 40% of its weight when injected with leptin. Courtesy of John Soltis, The Rockefeller University, New York, NY

Activity Lack of exercise is a major contributor to obesity. Just watching TV for two hours resulted in a 23% increase of weight when other factors were controlled (Hu & others, 2003).

Food Consumption Over the past 40 years, average weight gain has increased. Health professionals are pleading with US citizens to limit their food intake.

Losing Weight In the US, two-thirds of the women and half of the men say they want to lose weight. The majority of them lose money on diet programs.

Plan to Lose Weight When you are motivated to lose weight, begin a weight-loss program, minimize your exposure to tempting foods, exercise, and forgive yourself for lapses. Joe R. Liuzzo

Summary

Chapter 10: Motivation and Emotion

The Motivation of Hunger and Eating: Biological Factors Brain regulation –Lateral and ventromedial hypothalamus –Paraventricular nucleus Glucose and digestive regulation –Glucostatic theory Hormonal regulation –Insulin and leptin

Fig. 10-3, p. 379

p. 378

The Motivation of Hunger and Eating: Environmental Factors Learned preferences and habits –Exposure –When, as well as what Food-related cues –Appearance, odor, effort required Stress –Link between heightened arousal/negative emotion and overeating

Eating and Weight: The Roots of Obesity Evolutionary explanations Genetic predisposition –Body Mass Index and adoption study The concept of set point/settling point Dietary restraint

Fig. 10-5, p. 383

p. 380

Fig. 10-4, p. 382

Bell-ringer 4: Are you at your “ideal” weight? What is the “ideal” weight? Why do you think some people suffer from disorders that change their perception of their own weight?Are you at your “ideal” weight? What is the “ideal” weight? Why do you think some people suffer from disorders that change their perception of their own weight?

III. Motivation: Hunger A. The Ancel Keys Study on hungerA. The Ancel Keys Study on hunger –1. Selected 36 men from 100 volunteers for the study –2. First fed them just enough to maintain their initial weight –3. Then for 6 months cut this food level in half

–4. Men began unconsciously changing behaviors, conserving energy and becoming listless –5. Consistent with Maslow’s theory, the men became obsessed with food

B. The Physiology of HungerB. The Physiology of Hunger –1. Washburn and Cannon study on hunger a. Cannon swallowed a balloon that electronically monitored his stomach contractionsa. Cannon swallowed a balloon that electronically monitored his stomach contractions b. Cannon pressed a button every time he felt hungryb. Cannon pressed a button every time he felt hungry c. These feelings coincided with the contractionsc. These feelings coincided with the contractions d. some diet aids work by filling the stomach with indigestible fiberd. some diet aids work by filling the stomach with indigestible fiber

–2. Body Mechanisms for Hunger a. Vagus Nerve = registers stretching of the stomach and sends a signal to the brain indicating satiety (a feeling of being full)a. Vagus Nerve = registers stretching of the stomach and sends a signal to the brain indicating satiety (a feeling of being full) b. Duodenum = an opening (sphincter) to the intestinesb. Duodenum = an opening (sphincter) to the intestines –Part of the small intestine –pressure on the duodenum produces feelings of satiety –Releases CCK a hormone –3. Body Chemistry a. CCK (cholecystokinin)a. CCK (cholecystokinin) –closes the sphincter between the stomach and duodenum –thus causing the stomach to fill faster –Also present in a similar form in the brain

b. Glucoseb. Glucose –Glucose = the form of sugar that circulates in the blood and provides the major source of energy for body tissues. It is the most important fuel of the brain –Insulin = a hormone that enables glucose to enter the cells and provide energy. »After eating insulin levels rise allowing the glucose into the cells of the body »This produces a feeling of satiety »If glucose levels fall then you become hungry again c. Glucagon has the opposite effect it causes the liver to convert stored nutrients into glucose = hungerc. Glucagon has the opposite effect it causes the liver to convert stored nutrients into glucose = hunger

d. Leptins – The hypothalamus measures levels of this protein produced by bloated fat cells. When leptin levels rise the brain via the PARAVENTRICULAR HYPOTHALAMUS (PVN) sends messages to inhibit the production of NPY which inhibits eatingd. Leptins – The hypothalamus measures levels of this protein produced by bloated fat cells. When leptin levels rise the brain via the PARAVENTRICULAR HYPOTHALAMUS (PVN) sends messages to inhibit the production of NPY which inhibits eating

e. Orexin = when levels are high you feel hungrye. Orexin = when levels are high you feel hungry f. Neuropeptide Y (NPY) = when levels are high you want to eatf. Neuropeptide Y (NPY) = when levels are high you want to eat g. Peptide YY (PYY) = when levels are high you are fullg. Peptide YY (PYY) = when levels are high you are full h. Serotonin = When levels are high your desire to eat decreasesh. Serotonin = When levels are high your desire to eat decreases i. Norepinephrine = When levels are high your desire to eat increasesi. Norepinephrine = When levels are high your desire to eat increases

–4. Brain mechanism for Hunger -The Hypothalamus a. Lateral Hypothalamus (LH) if stimulated the animal will eat, if destroyed it will stop eating almost entirely.a. Lateral Hypothalamus (LH) if stimulated the animal will eat, if destroyed it will stop eating almost entirely. b. Ventromedial Hypothalamus (VMH) if stimulated animal will stop eating if destroyed will become obese.b. Ventromedial Hypothalamus (VMH) if stimulated animal will stop eating if destroyed will become obese. c. These two mechanism are believed to work together to determine how much glucose is stored as fat and how much is left available for immediate activity (and to minimize hunger).c. These two mechanism are believed to work together to determine how much glucose is stored as fat and how much is left available for immediate activity (and to minimize hunger).

–5. Genetic explanations a. Set Point Theorya. Set Point Theory –The point at which an individual’s weight thermostat is supposedly set –When the body falls below this weight, an increase in hunger and lowered metabolic rate may act to restore the lost weight b. Basal metabolic rate = the body’s resting rate of energyb. Basal metabolic rate = the body’s resting rate of energy c. # of fat cells which can be impacted by genetics and childhood eating patternsc. # of fat cells which can be impacted by genetics and childhood eating patterns d. The Obese Gene – some people are born with the Obese Gene, which inhibits the production of Leptin which signals the brain about the level of fat in the body, therefore may have an impact on eatingd. The Obese Gene – some people are born with the Obese Gene, which inhibits the production of Leptin which signals the brain about the level of fat in the body, therefore may have an impact on eating

C. Psychological ExplanationsC. Psychological Explanations –1. Media – commercials are constantly bombarding us with images of tasty (but fattening) foods. –2. Use of food as a reward – some parents and teachers use food as a reward…thus going back to operant conditioning the food becomes a reward that a person associates with good things. –3. Modeling – remember Bandura’s studies on modeling – children will model their behavior based on what they see.

–3. External Incentives and Hunger a. The Rodin “Steak” Study and the difference between externals and internalsa. The Rodin “Steak” Study and the difference between externals and internals –study by Rodin on hungry subjects (hadn’t eaten for 18 hours –While they were getting blood work done a sizzling steak rolled in on a cart –Researchers monitored changes in insulin levels. –Externals who are impacted more by outside motivations had greater insulin peaks signaling a greater need to eat. –4. Taste Preference: Biology or Culture a. Some foods likes like sweet and salty are genetic and universala. Some foods likes like sweet and salty are genetic and universal b. Some are learned like a desire for highly salty foods or food aversions that are acquired after being nauseousb. Some are learned like a desire for highly salty foods or food aversions that are acquired after being nauseous

c. How are they culturalc. How are they cultural –dog and cat shunned in Europe and America yet prized elsewhere –Beef eaten in Europe and US but forbidden to Hindu’s –We are somewhat “neophobic” that is we fear new and novel foods especially those that are animal based. –This “neophobia” extends to animals and probably served an adaptive purpose in keeping us alive by avoiding the unfamiliar. d. The Garcia Effect – remember from learning theory that John Garcia studied how taste aversions develop. The Garcia effect occurs when nausea is paired or associated with a particular food.d. The Garcia Effect – remember from learning theory that John Garcia studied how taste aversions develop. The Garcia effect occurs when nausea is paired or associated with a particular food.

D. Eating DisordersD. Eating Disorders –1. Anorexia Nervosa - an eating disorder in which a normal-weight person diets and becomes significantly underweight, yet still feeling fat, continues to starve

a. symptoms =a. symptoms = –Refusal to maintain a normal body weight –Intense fear of gaining weight –Significant disturbance in the perception of the shape or size of their body. “feels fat” –Maintains a weight that is at or below 85% of a normal body weight –Post-menarcheal females must have missed 3 consecutive periods. amenorrhea) –Some will grow lanugo – a fine silky hair on their trunks and extremities and even face b. Two Sub typesb. Two Sub types –Restricting type – this subtype involves strict dieting, fasting or exercise to lose or maintain weight. –Binge/Eating Purge type - goes on binge eating sprees then uses various methods (vomiting, laxatives or enemas) to purge the food from the system

–2. Bulimia Nervosa = an eating disorder characterized by episodes of overeating followed by vomiting, laxative use, fasting or excessive exercise. a. Symptomsa. Symptoms –Recurrent episodes of binge eating »Eating in a discrete period of time an amount of food that is definitely larger than most people would eat during a similar period. »A sense of lack of control over the eating episode –Recurrent inappropriate compensatory measures such as vomiting or use of laxatives –Should occur on average of twice a week for at least 3 months b. Subtypesb. Subtypes –Purging type – self induced vomiting or the use of laxatives, diuretics or enemas –Non purging type – exercise or fasting but no vomiting.

–3. Possible causes of eating disorders a. Family lifea. Family life –In bulimia patients they often include incidence of alcoholism, obesity, and depression –Families that set high standards, fret about falling short of expectations and are intensely concerned with how they are perceived by others b. Genetic influences = More common in twinsb. Genetic influences = More common in twins

c. Cultural Influencesc. Cultural Influences –The Bathing suit test - have males and females take at test in their bathing suits - females did worse –The Fallon & Rozzin study - women’s ideal body weight was less than their current weight, but also that the weight they thought men preferred was less than the weight men actually preferred –Impact of the media - In Fiji after TV introduced the number of girls who induced vomiting quintupled - women who watched TV 3 or more nights a week are 50% more likely to consider themselves fat –Once was more common among white women, but the number of cases in African American women has increased.

–4. Treatment – for eating disorders a. Anorexia –May start with inpatient care for anorexics who are at a critically low weight. This is referred to as supportive nursing care –Some form of psychotherapy is usually required to get at the root cause of the faulty cognitions and perceptions. b. Bulimia –Cognitive therapy is very popular right now for bulimic patients. –Antidepressant medications –Group therapy