Unit 15: Motivation

                MOTIVATIONAL CONCEPTS
Motivation:
a need or desire that energizes and directs behavior.
Instinct: a complex behavior that is rigidly patterned throughout a species and is unlearned (e.g., imprinting in birds or the return of salmon to their birthplace to spawn).  Reflexes in human infants are to simple to be considered instincts.
Drive-Reduction Theory: the idea that a physiological NEED creates an aroused state of tension (DRIVE) that motivates an organism to satisfy that need.

NEED (for food or water)→DRIVE (hunger or thirst)→DRIVE-REDUCING BEHAVIORS (eating or drinking).

Drive-Reduction Theory is based on the Concept of Homeostasis.
       
Homeostasis: a tendency to maintain a balanced or constant internal state; the regulation of any aspect of body chemistry, such as blood glucose, around a particular level.
Arousal Theory: rather that reducing a physiological need or tension state, some motivated behaviors increase arousal.  Curiosity-driven behaviors, for example, suggest that too little as well as too much stimulation can motivate people to seek an optimum level of arousal.
Incentive Theory: Theory that even if a need or drive is not originally present, positive or negative environmental stimuli may motivate behavior (e.g., after finishing a big meal, and feeling totally satisfied, we may become hungry again if we see or smell a delicious dessert).
Hierarchy of Needs: Maslow's pyramid of human needs, beginning at the base with physiological needs that must first be satisfied before higher-level needs become active.  SEE HANDOUT

                               HUNGER
Glucose:
the form of sugar that circulates in the blood and provides the major source of energy for body tissues.  When blood glucose levels are low, we feel hungry.

Orexin: When blood-glucose is low, the lateral hypothalamus releases orexin, which makes us even more hungry.
Lateral Hypothalamus: the "hunger center" of the brain.  When blood glucose is low, the lateral hypothalamus kicks on, releases orexin and we feel hungry.
Ventromedial Hypothalamus: the "satiety center" of the brain.  When blood glucose is high (after we have eaten), the ventromedial hypothalamus kicks in and we no longer feel hungry.
Insulin: Substance released from the pancreas.  When blood glucose rises, insulin is released to allow the glucose to move from the blood to the tissues of the body.
Set Point: the point at which an individual's "weight thermostat" is supposedly set. When the body falls below this weight, an increase in hunger and a lowered metabolic rate may act to restore the lost weight.
Basal Metabolic Rate: the body's resting rate of energy expenditure.
                           Eating Disorders
Anorexia Nervosa:
an eating disorder in which a normal-weight person (usually an adolescent female) diets and becomes significantly underweight (15% or more), yet, still feeling fat, continues to diet.
Bulimia Nervosa: an eating disorder characterized by episodes of overeating, usually of high-calorie foods, followed by vomiting, laxative use, fasting, or excessive exercise.  These individuals are not typically underweight.
                    SEXUAL MOTIVATION
Sexual Response Cycle:
the four stages of sexual responding described by Masters and Johnson--excitement, plateau, orgasm, and resolution.
Refractory Period: a resting period after orgasm, during which a man cannot achieve another orgasm.
Sexual Disorder: a problem that consistently impairs sexual arousal or functioning.  They include impotence andpremature ejaculation in men and orgasmic dysfunction in women.
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