Let’s begin by defining our terms—a particularly important task in the psychology of emotion and mood. Fortunately, the task is easy. We won’t need strange new technical terms. Words you already use to discuss your feelings will prove useful (see Hacker, 2004).

What is “emotion”? Let’s see how people use the term. In English, “emotion” describes psychological experiences with three components: (1) a feeling (if you say that you’re experiencing an emotion, you’re inevitably feeling good or bad), (2) a thought (when experiencing an emotion, such as sadness or anger, you usually are thinking about the person or event that caused the emotional reaction to occur), and (3) bodily arousal (your physiological state is different than it was before the emotion occurred; Wierzbicka, 1999). Here’s an example. Suppose a driver cuts you off in traffic and you experience an emotion: anger. The emotion includes the three components:

If one of these components were missing, you would not say that you were experiencing an emotion. For example, suppose #3, bodily arousal, had been absent; perhaps you responded calmly, merely uttering soft-spoken words such as “It is unfortunate how many poor drivers populate our roadways.” Thanks to the calm state of your body, you would not say that you had “gotten emotional” (i.e., had experienced an emotion) when cut off.

In addition to these three key components—thought, feeling, bodily arousal—most emotions have a fourth component: facial expression (Ekman, 2003). You often can tell at a glance not only that a person is emotionally aroused, but also what emotion he or she is feeling (Figure 10.1).

Not all languages of the world use the word “emotion” in exactly the same way (Wierzbicka, 1999). Yet, for our purposes here, the way you naturally use “emotion” in English suffices to define the term. An emotion is a psychological state that combines feelings, thoughts, and bodily arousal and that often has a distinctive accompanying facial expression.

You already know that moods differ from emotions—your everyday use of the words reveals your knowledge. If a relationship broke up and you started crying, you’d say that you “got emotional” not that you “became moody.” If you’ve been feeling grouchy and depressed all day, you would say you are “in a bad mood.” “Emotion” and “mood” refer to different psychological states. Let’s look at some differences.

Mood can thus be defined as a prolonged, consistent feeling state, whether that state is positive (a “good mood”) or negative (a “bad mood”).

With these definitions in place, let’s now look in detail at the psychology of emotion.