After Chapter 5.2, you will be able to:
Emotion is a natural instinctive state of mind derived from one’s circumstances, mood, or relationships with others. The word emotion is derived from the same Latin word as motivation. What does psychology have to tell us about emotions?
There are three elements of an emotion: the physiological response, the behavioral response, and the cognitive response.
When a feeling is first experienced, arousal is stimulated by the autonomic nervous system. The physiological component includes changes in heart rate, breathing rate, skin temperature, and blood pressure. While it may be hard to recognize these changes and associate them with an emotion in everyday life, these changes have been detected in laboratory settings. Some emotions, such as fear, aggression, and embarrassment, are associated with more pronounced physiological changes than others.
The behavioral component of an emotion includes facial expressions and body language. For example, a smile, a friendly hand gesture, or even a subtle head tilt toward someone are commonly recognized as warm and happy signals. On the other hand, a frown, slumping of the shoulders, and looking downward are recognized as sad or downtrodden signals.
Finally, the cognitive component of emotion is the subjective interpretation of the feeling being experienced. Determination of one’s emotion is largely based on memories of past experiences and perception of the cause of the emotion.
Darwin made the argument that emotions are a result of evolution; thus, emotions and their corresponding expressions are universal. He explained that all humans evolved the same set of facial muscles to show the same expressions when communicating emotion, regardless of their society or culture. This sparked an ongoing discussion of the relationship between emotion and culture among psychologists and sociologists. Paul Ekman described a set of basic emotions that are recognized by societies around the world, and further identified that six emotions are associated with consistent facial expressions across cultures. Ekman and other psychologists have revised this list; one of the more well-recognized sets consists of seven universal facially expressed emotions and includes: happiness, sadness, contempt, surprise, fear, disgust, and anger. These emotions correspond to the distinctive facial expressions explained in Table 5.1 and depicted in Figure 5.5.
| Emotion | Facial Expression Cues |
| Happiness | Smile, wrinkling around eyes, raised cheeks |
| Sadness | Frown, inner eyebrows pulled up and together |
| Contempt | One corner of the mouth pulled upwards |
| Surprise | Eyes widen, eyebrows pulled up and curved, jaw opens |
| Fear | Eyes widen, eyebrows pulled up and together, lips pulled toward ears |
| Disgust | Nose wrinkling and/or raising of upper lip |
| Anger | Glaring, eyebrows pulled down and together, lips pressed together |
While emotions are experienced universally, it is argued that they can be affected greatly by culture. Cultural dissimilarities in emotion include varying reactions to similar events, differences in the emotional experience itself, the behavior exhibited in response to an emotion, and the perception of that emotion by others within the society.
In accordance with Darwin’s thoughts on universal emotion, the evolutionary perspective states that everything we do, think, and feel is based on specialized functional programs designed for any problem we encounter. These programs are functionally coordinated in order to produce a cohesive response. Emotions are thought to be evolutionary adaptations due to situations encountered over the evolutionary history of the human species that guide sensory processing, physiological response, and behavior. Further, different emotions are thought to have evolved during different periods in history. Among the earliest to develop were primal emotions, such as fear; other, more evolutionarily progressive emotions include social emotions, such as guilt and pride.
Early psychologists believed that the cognitive component of emotion led to the physiological component, which then produced the behavioral component. In other words, the feeling of anger started with perception of a negative stimulus, which caused physiological changes, such as increased skin temperature, which then resulted in behavior, such as yelling. This explanation assumes that feeling precedes arousal, which precedes action.
William James, the founder of functionalist theory, viewed the progression of these emotional elements differently. Around the same time, Carl Lange developed a theory of emotion similar to that of James’s. The explanation developed by the two is referred to as the James–Lange theory of emotion. According to the theory, a stimulus results first in physiological arousal, which leads to a secondary response in which the emotion is labeled. James believed that when peripheral organs receive information and respond, that response is then labeled as an emotion by the brain. For example, a car cutting you off on the highway is a stimulus for elevated heart rate and blood pressure, increased skin temperature, and dry mouth. These physiological responses result in the cognitive labeling of anger: I must be angry because my skin is hot and my blood pressure is high. By extension, an emotion would not be processed without feedback from the peripheral organs; this theory predicts that individuals who cannot mount a sympathetic response, like patients with spinal cord injuries, should show decreased levels of emotion. Subsequent studies have proven this claim to be false; spinal cord injury subjects continue to show the same level of emotion after their injuries as before.
Walter Cannon and Philip Bard developed another scheme for explaining emotional components, referred to as the Cannon–Bard theory of emotion. In an attempt to test the James–Lange theory, Cannon studied the expression of emotion and its relationship to feedback from the sympathetic nervous system using cats whose afferent nerves had been severed. He hypothesized that physiological arousal and feeling an emotion occur at the same time, not in sequence. Thus, severing the feedback should not alter the emotion experienced. In this theory, a person will respond with action after experiencing the emotion both mentally and physically. Bard, a student of Cannon’s, further explained that when exposed to a stimulus, sensory information is received and sent to both the cortex and the sympathetic nervous system simultaneously by the thalamus. Thus, the Cannon–Bard theory of emotion, depicted in Figure 5.6, states that the cognitive and physiological components of emotion occur simultaneously and result in the behavioral component of emotion, or action: I am afraid because I see a snake and my heart is racing . . . Let me out of here!
While critics of the James–Lange theory cite the severed afferent nerve study as support for the Cannon–Bard theory, there are also weaknesses in this theory. The Cannon–Bard theory fails to explain the vagus nerve, a cranial nerve that functions as a feedback system, conveying information from the peripheral organs back to the central nervous system.
A third theory is the Schachter–Singer theory of emotion, also termed the cognitive arousal theory or the two-factor theory. It states that both arousal and the labeling of arousal based on environment must occur in order for an emotion to be experienced: I am excited because my heart is racing and everyone else is happy. What is unique to the Schachter–Singer theory is this aspect of cognitive appraisal: to feel an emotion, one must consciously analyze the environment in relation to nervous system arousal. To study this, Stanley Schachter and Jerome Singer gave injections of epinephrine or placebo to groups of subjects that were either informed, ignorant, or misinformed. They also manipulated external cues in the study by having an actor act either happy or angry. They observed that epinephrine did result in increased physiological arousal; however, they also discovered that the environment and cognitive processing affected the emotion experienced by the subjects. The misinformed and ignorant groups experienced the highest levels of emotion. Schachter and Singer explained this by stating that a subject experiencing physiological arousal with no explanation or with a misleading explanation will attribute that arousal to the surrounding environment, and label herself as happy or angry based on the behavior of the actor. In other words, the presence of unexpected arousal plus an environment that encourages a particular emotion is sufficient to create that emotion in the subject. Contrarily, the informed group knew to expect physiological arousal from the drug, and thus attributed their feelings to being side effects, rather than emotions.
The three theories of emotion discussed in this section are summarized in Table 5.2.
| Theory | First Response | Second Response | |
| James–Lange | Stimulus | Nervous system arousal | Conscious emotion |
| Cannon–Bard | Nervous system arousal and conscious emotion | Action | |
| Schachter–Singer | Nervous system arousal and cognitive appraisal | Conscious emotion | |
The MCAT will expect that you have a solid understanding of the differences in emotional processing described by each of the three theories of emotion. It is best to mentally sort these theories by “first response” and “second response” to the stimulus.
Experiencing emotion is a complex process involving many parts of the brain. The most notable of these circuits is the limbic system, a complex set of structures that reside below the cerebrum on either side of the thalamus, as shown in Figure 5.7. The system is made up of the amygdala, thalamus, hypothalamus, hippocampus and fornix, septal nuclei, and parts of the cerebral cortex; it plays a large role in both motivation and emotion.
When specific areas of the limbic system are stimulated during brain surgery, patients have described sensations such as happiness, contentment, and pleasure; in other areas, they report fear and anxiety.
The amygdala is a small round structure that signals the cortex about stimuli related to attention and emotions. The amygdala processes the environment, detects external cues, and learns from the person’s surroundings in order to produce emotion. This region is associated with fear and also plays a role in human emotion through interpretation of facial expressions.
Research on rats has shown that when the amygdalae are damaged, the rats can no longer be classically conditioned to establish new fears. Similar effects have also been seen in humans wherein damage to this region prevents fear conditioning. This has been measured by autonomic nervous system responses as well as functional imaging.
The thalamus functions as a preliminary sensory processing station and routes information to the cortex and other appropriate areas of the brain. The hypothalamus, located below the thalamus, synthesizes and releases a variety of neurotransmitters. It serves many homeostatic functions, and is involved in modulating emotion. Indeed, by controlling the neurotransmitters that affect mood and arousal, the hypothalamus largely dictates emotional states.
The hippocampus, within the temporal lobe, is primarily involved in creating long-term memories. Along with the functions of the amygdala and hypothalamus, the storage and retrieval of emotional memories is key in producing an emotional response. The hippocampus also aids in creating context for stimuli to lead to an emotional experience. As described in Chapter 3 of MCAT Behavioral Sciences Review, memory systems can be divided into two categories: explicit and implicit. When an emotion is experienced, sensory systems transmit this information into both the explicit memory system, primarily controlled by the hippocampus in the medial temporal lobe, and the implicit memory system, controlled by the amygdala. Both memory systems are used for both the formation and retrieval of emotional memories, as shown in Figure 5.8. The conscious (explicit) memory is the memory of experiencing the actual emotion: remembering that you were happy at your high school graduation or that you were sad when you lost a loved one is explicit memory. Note that these are episodic memories: they are more properly considered memories about emotions than stored emotions. The unconscious (implicit) memory is referred to as emotional memory; this is the storage of the actual feelings of emotion associated with an event. When experiencing a similar event later on, these emotions may be retrieved. Thus, explicit memory of the emotion produces a conscious memory of the experience, and implicit memory determines the expression of past emotions. This distinction can be further identified when looking at individuals with posttraumatic stress disorder (PTSD). The explicit memory is the “story” of the event: what happened, where it occurred, who was involved, the fact that the scenario was traumatic, and so forth. The implicit memory corresponds to the sensations of unease and anxiety when put back into a similar environment.
The ability to distinguish and interpret others’ facial expressions is primarily controlled by the temporal lobe, with some input from the occipital lobe. This function is lateralized: the right hemisphere is more active when discerning facial expressions than the left. There are also gender differences: women demonstrate more activation of these brain areas than men. This ability is present but weak in children and develops into adulthood; adults are much more effective at identifying both positive and negative emotions.
The prefrontal cortex is the anterior portion of the frontal lobes and is associated with planning intricate cognitive functions, expressing personality, and making decisions. The prefrontal cortex also receives arousal input from the brainstem, coordinating arousal and cognitive states. It has been demonstrated that the left prefrontal cortex is associated with positive emotions and the right prefrontal cortex with negative emotions. The dorsal prefrontal cortex is associated with attention and cognition, while the ventral prefrontal cortex connects with regions of the brain responsible for experiencing emotion. Specifically, the ventromedial prefrontal cortex, shown in Figure 5.9, is thought to play a substantial role in decision-making and controlling emotional responses from the amygdala.
One of the most notable studies on prefrontal cortex function is that of Phineas Gage. Gage was involved in an accident in which a metal rod pierced his brain, destroying the left frontal lobe. Gage’s memory, speech, and motor skills were unaffected, but his personality was dramatically altered. Post-accident, Gage displayed irritable and impatient behavior, which inhibited his ability to complete simple tasks.
As described earlier, the autonomic nervous system is also related to emotion; specific physiological reactions are associated with specific emotions. Skin temperature, heart rate, breathing rate, and blood pressure are all affected when experiencing emotion. Decreased skin temperature is detected in subjects experiencing fear, while increased skin temperature is associated with anger. Increased heart rate is observed in subjects experiencing both anger and fear, while decreased heart rate is observed in happy subjects. Heart rate variability is another factor used to determine emotion. Decreased heart rate variability is associated with stress, frustration, and anger. Blood pulse volume increases with anger or stress, and decreases with sadness or relaxation. Skin conductivity is directly correlated with sympathetic arousal; however, a specific emotion cannot be identified by skin response. Diastolic blood pressure is increased to the greatest degree by anger, followed by fear, sadness, and happiness.