Physiological and psychological needs refer to deficits between a desired set of internal conditions in the body, brain, or psychologically regarding an activity or experience. A need motivates behaviors that results in need satisfaction; when not satisfied, psychological well-being declines. Needs exist as enduring traits because the environment lacks the means for satisfaction. Or they lie dormant until activated as need states by the appropriate conditions. Maslow's hierarchy of needs ranks them for their potency, while self-determination theory emphasizes the need for autonomy, affiliation, and competence. Psychological needs motivate behavior by need reduction (negative reinforcement) but also by added pleasure (positive reinforcement) as a product of need-reducing behaviors. Psychological needs are the basis for motives, such as achievement, affiliation/belonging, autonomy, closure, cognition, competence, meaning, power, and self-esteem.