Hull's proposal that all behaviour is motivated and that motivation stems from the satisfaction of homeostatic drives (e.g. hunger and thirst). Stimuli (e.g. food and water) that decreases the drivessubsequently reinforce the behaviour that led to them.
a drug which increases activation of the central nervoussystem and the autonomic nervous system;decreasing fatigue, increasing physical activity andalertness, diminish hunger, and result in a temporaryelevation of mood.