Emotions, like motives, both arouse and direct our behavior. They tend to prompt us to move toward or away from an object. However, also like motives, emotions may trigger a complex chain of behavior that may promote or interfere with the accomplishment of our goals. According to the Yerkes-Dodson law, the more complex the task, the lower the level of emotional arousal that can be tolerated without interfering with performance.

Robert Plutchik’s classification system for emotions uses a "circle" to position eight basic categories of emotions that motivate various kinds of adaptive behavior. However, not all cultures view or categorize emotions this way; some do not even have a word for emotion. Others describe feelings by their physical sensations.

A cross-cultural analysis of emotional expression has led Paul Ekman and his colleagues to argue for the universality of at least six emotions–happiness, surprise, sadness, fear, disgust, and anger. Many psychologists also add love to this list of basic emotions.

According to the James-Lange theory, environmental stimuli bring on physiological changes in our bodies and emotions then arise from those physical changes. The Cannon-Bard theory states that the processing of emotions and bodily responses occurs simultaneously rather than one after the other. The cognitive theory of emotion holds that the situation that we are in when we are aroused–the overall environment–gives us clues that help us interpret this general state of arousal. According to recent research, facial expression may influence emotions apart from cognition.