Psychology Emotion Introduction Theories & Biological Bases of Emotion
To view other notes of Psychology Click Here.
Introduction
The source of our emotions remains elusive. No one knows exactly where emotions come from, what makes us feel the way we do, or whether we can fully control the way we feel. Emotion is intimately related to cognition and culture, and it affects us physically: our bodies react to different emotional states, and we often show emotion physically. Researchers have proposed many theories about the source, purpose, and expression of emotion.
In many ways, our emotions define our existence—without them, most of us would not feel truly alive. We’ve all felt fear of a lurking stranger, pride at scoring well on a test, love, sadness, and loneliness. And between emotional extremes are the ups and downs of everyday life: frustration in a traffic jam, contentment over a satisfying lunch, amusement at a cartoon. We have much to learn about emotion—but we have also learned simply by being human and feeling things every day.
Theories of Emotion
Emotion is a complex, subjective experience accompanied by biological and behavioral changes. Emotion involves feeling, thinking, activation of the nervous system, physiological changes, and behavioral changes such as facial expressions.
Different theories exist regarding how and why people experience emotion. These include evolutionary theories, the James-Lange theory, the Cannon-Bard theory, Schacter and Singer’s two-factor theory, and cognitive appraisal.
Evolutionary Theories
More than a century ago, in the 1870s, Charles Darwin proposed that emotions evolved because they had adaptive value. For example, fear evolved because it helped people to act in ways that enhanced their chances of survival. Darwin believed that facial expressions of emotion are innate (hard-wired). He pointed out that facial expressions allow people to quickly judge someone’s hostility or friendliness and to communicate intentions to others.
Recent evolutionary theories of emotion also consider emotions to be innate responses to stimuli. Evolutionary theorists tend to downplay the influence of thought and learning on emotion, although they acknowledge that both can have an effect. Evolutionary theorists believe that all human cultures share several primary emotions, including happiness, contempt, surprise, disgust, anger, fear, and sadness. They believe that all other emotions result from blends and different intensities of these primary emotions. For example, terror is a more intense form of the primary emotion of fear.
The James-Lange Theory
In the 1880s, two theorists, psychologist William James and physiologist Carl Lange, independently proposed an idea that challenged commonsense beliefs about emotion. This idea, which came to be known as the James-Lange theory, is that people experience emotion because they perceive their bodies’ physiological responses to external events. According to this theory, people don’t cry because they feel sad. Rather, people feel sad because they cry, and, likewise, they feel happy because they smile. This theory suggests that different physiological states correspond to different experiences of emotion.
The Cannon-Bard Theory
The physiologist Walter Cannon disagreed with the James-Lange theory, posing three main arguments against it:
- People can experience physiological arousal without experiencing emotion, such as when they have been running. (The racing heart in this case is not an indication of fear.)
- Physiological reactions happen too slowly to cause experiences of emotion, which occur very rapidly. For example, when someone is in a dark alley alone, a sudden sound usually provokes an immediate experience of fear, while the physical “symptoms” of fear generally follow that feeling.
- People can experience very different emotions even when they have the same pattern of physiological arousal. For example, a person may have a racing heart and rapid breathing both when he is angry and when he is afraid.
Cannon proposed his own theory of emotion in the 1920s, which was extended by another physiologist, Philip Bard, in the 1930s. The resulting Cannon-Bard theory states that the experience of emotion happens at the same time that physiological arousal happens. Neither one causes the other. The brain gets a message that causes the experience of emotion at the same time that the autonomic nervous system gets a message that causes physiological arousal.
Schachter and Singer’s Two-Factor Theory
In the 1960s, Stanley Schachter and Jerome Singer proposed a different theory to explain emotion. They said that people’s experience of emotion depends on two factors: physiological arousal and the cognitive interpretation of that arousal. When people perceive physiological symptoms of arousal, they look for an environmental explanation of this arousal. The label people give an emotion depends on what they find in their environment.
Example: If a person finds herself near an angry mob of people when she is physiologically aroused, she might label that arousal “anger.” On the other hand, if she experiences the same pattern of physiological arousal at a music concert, she might label the arousal “excitement.”
Schachter and Singer agree with the James-Lange theory that people infer emotions when they experience physiological arousal. But they also agree with the Cannon-Bard theory that the same pattern of physiological arousal can give rise to different emotions.
Cognitive Appraisal
The psychologist Richard Lazarus’s research has shown that people’s experience of emotion depends on the way they appraise or evaluate the events around them.
Example: If Tracy is driving on a winding road by the edge of a high cliff, she may be concerned about the danger of the road. Her passenger, on the other hand, thinks about the beauty of the view. Tracy will probably feel frightened, while her passenger may feel exhilarated.
The Biological Bases of Emotion
The experience of emotion is accompanied by activation of two major areas of the nervous system: the brain and the autonomic nervous system.
Activation of Brain Regions
The area of the brain known as the limbic system is highly involved in emotion. One structure in the limbic system, called the amygdala, plays a particularly important role in regulating emotion.
Researchers believe that sensory information about emotion-evoking events moves along two pathways in the brain. The information goes first to the thalamus and from there moves simultaneously to the amygdala and the cortex of the brain. The amygdala processes the information quickly and sends signals to the hypothalamus, which in turn activates the autonomic nervous system. The cortex, on the other hand, processes the information more slowly, allowing people to appraise or evaluate the event.
Example: When information travels from the sense organs to the thalamus to the amygdala, people respond instantaneously, without thinking, to events in their environment. A parent may snatch her child away from a curb without thinking if she hears the sound of squealing tires coming toward them.
The Amygdala
Damage to the amygdala results in an inability to appropriately process fear. Animals with damaged amygdalas cannot develop conditioned fear responses. People with damaged amygdalas can’t recognize fear in other people, though they may be able to experience fear themselves.
Activation of the Autonomic Nervous System
The autonomic nervous system controls all the automatic functions in the body. See pages 51–52 for more information about the autonomic nervous system.
When an emotion-evoking event happens, the sympathetic branch of the autonomic nervous system, which prepares the body for action, begins to work. It sends signals to the adrenal gland, which secretes the hormones epinephrine and norepinephrine. These hormones in turn prepare a person to face the challenges of the event. The following physical responses are indicative signs in a man or woman:
- Blood pressure, heart rate, respiration rate, and blood sugar levels increase and prepare a person for action.
- Pupils dilate to let in more light for vision.
- The digestive processes slow down so that energy can be directed to the crisis at hand.
Autonomic Nervous System
The autonomic nervous system is made up of two parts: the sympathetic and parasympathetic nervous systems. Unlike the sympathetic nervous system, which prepares the body for action, the parasympathetic nervous system keeps the body still. The sympathetic nervous system involves expending energy, while the parasympathetic nervous system works to keep energy in the body.
Measuring Emotion
Researchers often use autonomic responses to measure emotion. One frequently used autonomic response is called the galvanic skin response. The galvanic skin response is an increase in the skin’s rate of electrical conductivity, which occurs when subjects sweat during emotional states. Researchers also use indicators such as blood pressure, muscle tension, heart rate, and respiration rate to measure emotion.
Polygraph Tests
The polygraph, or lie detector, is a device used to detect deception. In reality, the polygraph cannot detect deception. Instead, it measures autonomic indices of emotion. A subject is hooked up to the device and asked a series of neutral questions such as What is your name? Where do you live? and so on. The polygraph records the autonomic responses as the subject answers these questions, establishing the baseline, or normal pattern of autonomic activation. Then the subject answers other questions that can determine guilt or innocence, such as Where were you on the night of the murder?
