Motivation: process that influences the direction, persistence, and vigour of goal directed behavior. Instinct (fixed action pattern) an inherited characteristic that automatically produces a particular response when the organism is exposed to a particular stimulus. Theories faded due to circular reasoningpeople are greedy. Modern evolutionary psychologists propose that many motives have evolutionary underpinnings. Homeostasis a state of internal physiological equilibrium that the body strives to maintain. A sensory mechanism detecting changes in internal. A control centre receives information from sensors physiological disruptions to homeostasis produce drives. Clark hull proposes that reducing drives is the ultimate goal of motivated behavior. Flaws: found in certain behaviors, such as when people skip meals to diet (increases rather than decreases state of arousal) states of internal tension that motivate an organism that reduce this tension. Incentives environmental stimuli that pull an organism toward a goal.