drive-reduction theory

Meaning: Proposed by Clark Hull, the theory says a biological need, such as a lack of food or water, produces a drive, an unpleasant internal state of tension. Behavior is motivated to reduce that tension and restore homeostasis, and the reduction works as reinforcement, so actions that lowered the drive become more likely to recur. Primary drives are unlearned and biological (hunger, thirst); secondary drives are learned by association with primary ones (money, for example). Motivation here is a push from inside the body.

On the MCAT: A passage describes a behavior and asks which motivation theory explains it. Eating when hungry or drinking when dehydrated fits drive-reduction. Eating dessert when already full fits incentive theory, where external rewards pull behavior. Roller coasters, exploration and curiosity fit arousal theory, where people seek an optimal level of arousal (tied to the Yerkes-Dodson law). Instinct theory and Maslow's hierarchy of needs are other common answer choices.

Common confusion: A need is the physiological deficit; a drive is the psychological tension the need produces. Also, drive reduction explains many behaviors but not every one, since some behaviors raise tension or arousal rather than lower it.