| Theory | Its Big Idea |
|---|
| Instinct theory/evolutionary psychology | There is a genetic basis for unlearned, species-typical behavior (such as birds building nests or infants rooting for a nipple). |
| Drive-reduction theory | Physiological needs (such as hunger and thirst) create an aroused state that drives us to reduce the need (for example, by eating or drinking). |
| Arousal theory | Our need to maintain an optimal level of arousal motivates behaviors that meet no physiological need (such as our yearning for stimulation and our hunger for information). |
| Maslow’s hierarchy of needs | We prioritize survival-based needs and then social needs more than the needs for esteem and meaning. |