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Whether you are falling in love or grieving a death, you need little convincing that emotions involve the body. Feeling without a body is like breathing without lungs. Some physical responses are easy to notice. Other emotional responses we experience without awareness. Before examining our physical responses to specific emotions, consider another big question: How many distinct emotions are there?

31-3 What are some of the basic emotions?

Carroll Izard (1977) isolated 10 basic emotions (joy, interest-excitement, surprise, sadness, anger, disgust, contempt, fear, shame, and guilt), most present in infancy (FIGURE 31.3 below). Others believe that pride is also a distinct emotion, signaled by a small smile, head slightly tilted back, and an open posture (Tracey & Robins, 2004). Love, too, may be a basic emotion (Shaver et al., 1996). Izard has argued that other emotions are combinations of these 10, with love, for example, being a mixture of joy and interest-excitement. But are these emotions biologically distinct? Does our body know the difference between fear and anger?

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31-4 What is the link between emotional arousal and the autonomic nervous system?

In a crisis, the sympathetic division of your autonomic nervous system (ANS) mobilizes your body for fight or flight (FIGURE 31.4). It triggers your adrenal glands to release the stress hormones epinephrine (adrenaline) and norepinephrine (noradrenaline). To provide energy, your liver pours extra sugar into your bloodstream. To help burn the sugar, your respiration increases to supply needed oxygen. Your heart rate and blood pressure increase. Your digestion slows, diverting blood from your internal organs to your muscles. With blood sugar driven into the large muscles, running becomes easier. Your pupils dilate, letting in more light. To cool your stirred-up body, you perspire. If wounded, your blood would clot more quickly.

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When the crisis passes, the parasympathetic division of your ANS gradually calms your body, as stress hormones slowly leave your bloodstream. After your next crisis, think of this: Without any conscious effort, your body’s response to danger is wonderfully coordinated and adaptive—preparing you to fight or flee. So, do the different emotions have distinct arousal fingerprints?

31-5 Do different emotions activate different physiological and brain-pattern responses?

Imagine conducting an experiment measuring the physiological responses of emotion. In each of four rooms, you have someone watching a movie: In the first, the person is viewing a horror show; in the second, an anger-provoking film; in the third, a sexually arousing film; in the fourth, a boring film. From the control center, you monitor each person’s perspiration, breathing, and heart rate. Could you tell who is frightened? Who is angry? Who is sexually aroused? Who is bored?

With training, you could probably pick out the bored viewer. But discerning physiological differences among fear, anger, and sexual arousal is much more difficult (Barrett, 2006). Different emotions can share common biological signatures.

A single brain region can also serve as the seat of seemingly different emotions. Consider the broad emotional portfolio of the insula, a neural center deep inside the brain. The insula is activated when we experience various negative social emotions, such as disgust. In brain scans, it becomes active when people bite into some disgusting food, smell disgusting food, think about biting into a disgusting cockroach, or feel moral disgust over a sleazy business exploiting a saintly widow (Sapolsky, 2010). Similar multitasking regions are found in other brains areas.

Yet our emotions—such as fear, anger, sexual arousal, and disgust—feel different to us, and they often look different to others. We may appear “paralyzed with fear” or “ready to explode.” Fear and joy prompt similar increased heart rate, but they stimulate different facial muscles. During fear, your brow muscles tense. During joy, muscles in your cheeks and under your eyes pull into a smile (Witvliet & Vrana, 1995).

Some of our emotions also differ in their brain circuits (Panksepp, 2007). Observers watching fearful faces showed more amygdala activity than did other observers who watched angry faces (Whalen et al., 2001). Brain scans and EEG recordings show that emotions also activate different areas of the brain’s cortex. When you experience negative emotions such as disgust, your right prefrontal cortex tends to be more active than the left. Depression-prone people, and those with generally negative personalities, have also shown more right frontal lobe activity (Harmon-Jones et al., 2002).

Positive moods tend to trigger more left frontal lobe activity. People with positive personalities—exuberant infants and alert, enthusiastic, energized, and persistently goal-directed adults—have also shown more activity in the left frontal lobe than in the right (Davidson, 2000, 2003; Urry et al., 2004).

To sum up, we can’t easily see differences in emotions from tracking heart rate, breathing, and perspiration. But facial expressions and brain activity can vary from one emotion to another. So, do we, like Pinocchio, give off telltale signs when we lie? For more on that question, see Thinking Critically About: Lie Detection.