Instincts, Drives, and Hunger
Instincts A pattern of behavior that is passed on through a species that can’t be unlearned Building nests Swimming upstream Migration Rooting
Drives An aroused state of tension motivating a course of action You are driven to fulfill physiological needs Plan to get food, avoid pain, etc.
Drive-Reduction Theory You have a need: food/water You have a drive: hunger/thirst You have a drive reducing behavior: eating/drinking
Incentives Positive or negative environmental stimulus that motivates behavior Physical attraction Fear of disapproval Scholarships Failure
Ancil Keys WWII Prison Camps Fed enough to maintain initial weight, then cut food supplies in half The men became obsessed with food Nothing else was important
Physiology of Hunger Walter Cannon – swallowed balloon to see if stomach contractions & hunger pangs were related He had stomach contractions when he felt hungry
Body Chemistry and the Brain The hypothalamus has two centers within that help control eating Lateral hypothalamus (LH) brings on hunger Ventromedial hypothalamus (VM) depresses hunger
Hormones and Pills Scientists know of hormones and proteins that stimulate hunger and depress hunger (leptin, ghrelin, PPY) Trying to find a miracle pill to work with these to regulate weight
Set Point Theory Older theory Body’s weight thermometer If you eat too much, you body is supposed to stop at your set point Same thing happens of you don’t eat enough
Basal Metabolic Rate In order to maintain our bodies’ set point, our bodies need to maintain their basal metabolic rate Too much food – fidget Too little food – slow down body process
Eating Disorders Cultures shape “beauty” - thin Men/women views of what’s thin
Anorexia Normal sized people become obsessed with losing weight Continues to feel fat Diets turn to starvation At least 15% below normal body weight
Bulimia Quick fix to lose weight Binge eat high calorie foods followed by: –Vomiting –Laxative use –Fasting –Excessive exercise