Motivation

Motivation

a need or desire that energizes and directs behavior

Instince theory/evolutionary perspective

genetically predisposed behavior; unlearned

Instinct

a complex behavior that is rigidly patterned through a species and is unlearned

Drive-reduction theory

idea that a physiological need creates an aroused tension state (a drive) that motivates an organism to satisfy the need

Homeostasis

tendency to maintain a balanced/constant internal state; regulation of any aspect of body chemistry around a particular level. The physiological aim of drive reduction - the “push”

Incentive

a positive or negative environmental stimulus that motivates behavior. The “pull”.

Optimal arousal theory

suggests that people are motivated to find an ideal level of arousal (alertness and engagement) where performance is best, avoiding both boredom (too low arousal) and stress (too high arousal)

Hierarchy of needs

created by Abraham Maslow; pyramid of human needs starting with physiological needs that must first be satisfied before higher-level needs and then the psychological needs become active

Hypothalamus

influences hunger

Ancel Keys

experiment led by Keys; fed 36 male volunteers enough to maintain initial weight and then cut this food level in haklf for 6 months. Men began unconsciously conserving energy. Became obsessed with food. Dropped weight by 1/4.

A.L. Washborn and Walter Cannon

swallowed balloon that inflated, filled stomach, and transmitted contractions to a recording device. Pressed a key when hungry and found contractions when hunger, but hunger persists even with out a stomach/contractions.

lateral hypothalamus

brings hunger

ventromedial hypothalamus

depresses hunger

ghrelin

hunger-arousing hormone, secreted by an empty stomach

obestatin

sends out fullness signal that suppresses hunger

PYY

appetite-suppressing, secreted by digestive track

leptin

protein secreted by fat cells and acts to decrease rewarding pleasure of food

set point

the point where an individual’s “weight thermostat” is supposedly set. When body falls below, increase in hunger and decrease in metabolic rate may act to restore the lost weight. Influenced by genetics.

basal metabolic rate (BMI)

body’s resting rate of energy expenditure (maintain basic body functions). Helps regulate weight by changing energy expenditure.

Paul Rozin

tested 2 patients w/no memory for events occurring more than 1 minute ago and offered lunch 20 minutes after eating, and again, and again. They readily ate 2nd and sometimes 3rd lunch, suggesting part of knowing when to eat is our memory of our last meal.

Neophobia

dislike of things unfamiliar. Biologically adaptive since protected ancestors from potentially toxic substances.

Anorexia nervose

eating disorder in which person diets and becomes significantly underweight, yet, still feeling fat, continues to starve. Charactered by episodes of overeating followed by vomiting, laxative use, fasting, or excessive exercise

binge-eating disorder

significant binge-eating episodes, followed by distress, disgust, or guilt, but without the compensatory purging, etc.

Adipose Cellularity

number of fat cells can only, increase never decrease (though can shrink in size). This makes it so that formerly obese people require lower food intake to maintain the same weight as someone who wasn’t obese.