DO NOW What was your least favorite task you had to complete during your break? What motivated you to actually get it done? What do you think motivates people to do things they dislike to do?

Motivation  a need or desire that energizes and directs behavior  Instinct theory / Evolutionary Perspective  Drive-Reduction Theory  Arousal Theory  Hierarchy of Needs

Instinct Theory (Evolutionary Perspective) Instinct Theory: we are motivated by our inborn automated behaviors. No longer accepted - Primarily applies to animals, NOT HUMANS Most important human behavior is learned and is rarely inflexible

Drive Reduction Theory Our behavior is motivated by BIOLOGICAL NEEDS. Wants to maintain homeostasis. Ex: shivering When we are not at homeostasis, we have a need that creates a drive. Drive-reducing behaviors (eating, drinking) Need (e.g., for food, water) Drive (hunger, thirst) PHYSIOLOGICALPSYCHOLOGICAL

Drive Reduction Push and Pull Theory  Homeostasis (push) [need]  Drive created by your body  regulation of any aspect of body chemistry around a particular level  Incentive (pull) [incentive]  environmental stimulus that motivates behavior  Need + incentive = strong drive  Hunger + freshly baked pie = dinner time

Arousal Theory We are motivated to seek an optimum level of arousal. Yerkes-Dodson Law: a moderate amount of stress or anxiety increases our performance

Maslow’s Hierarchy of Needs Abraham Maslow said we are motivated by needs, and all needs are not created equal. We are driven to satisfy the lower level needs first.

Motivation of HUNGER Multiple contributors to feeling of hunger: Stomach contractions Blood Sugar Glucose Hypothalamus Stomach hormones Basal Metabolic Rate

Biology of Hunger  Stomach contractions accompany our feelings of hunger  Stomach contractions (pangs) send signals to the brain making us aware of our hunger.

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

BUT… hunger remains if stomach is removed, therefore hunger does not come solely from the stomach 1938 study - researchers removed rat stomachs, connected the esophagus to the small intestines, and the rats still felt hungry (and ate food).

Glucose: C 6 H 12 O 6 The glucose level in blood is maintained by your pancreas. Insulin decreases glucose in the blood, when the level gets too low, messages are sent to our brain and we feel hungry. Glucose Molecule Rat Hypothalamus

Brain Basis of Hunger Stimulation to lateral (sides of) hypothalamus elicits hunger Stimulation to ventromedial (lower-mid) hypothalamus depresses hunger Rat on right has lesion on ventromedial hypothalamus; caused its weight to triple 

Hypothalamus Lateral Hypothalamus When stimulated it makes you hungry. When lesioned (destroyed) you will never be hungry again. Ventromedial Hypothalamus When stimulated you feel full. When lesioned you will never feel full again.

Leptin Fat cells in our body produce the hormone leptin Hypothalamus monitors these levels High levels of leptin signal the brain to reduce appetite or increase the rate at which fat is burned. Leptin deficiency can cause obesity

Set Point Theory The hypothalamus acts like a thermostat. Wants to maintain a stable weight. Activate the lateral when you diet and activate the ventromedial when you start to gain weight. Metabolism: body’s base rate of energy expenditure

Culture and Hunger

Taste Preference: Biology or Culture? Body chemistry and environmental factors influence not only how much or 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.

Obesity Severely overweight to the point where it causes health issues. Mostly eating habits but some people are predisposed towards obesity. As you gain weight, you create MORE and BIGGER fat cells… as you lose the weight, the cells reduce is size BUT NEVER IN NUMBER. Click on the picture to see some case studies on obesity.

Eating Disorders Bulimia Nervosa Characterized by binging (eating large amounts of food) and purging (getting rid of the food). 1% of population

Anorexia Nervosa Starve/exercise themselves to below 85% of their normal body weight. See themselves as fat. Vast majority are women. 0.6% of population Click on the woman to watch a case study of an anorexic.

Eating Disorders What causes eating disorders? –Genetics may influence susceptibility –Those with greatest body dissatisfaction –Western cultures idolize thin women »Cultural pressure transmitted by the “thin-ideal” exemplified in advertisementsCultural pressure transmitted by the “thin-ideal” exemplified in advertisements

Women’s Body Images