The Making of the Mind: The Neuroscience of Human Nature (23 page)

The visual and spatial stores of human working memory allow us to maintain transient mental images for a period of time. By allocating executive attention to these mental representations, it is possible to keep them active and constantly in mind. Imagery of desired foods, drinks, or smokes become very difficult to get out of one's mind as the cravings for them occupy more and more of the resources of working memory. In one study, people were asked to imagine that they were eating their favorite food as a way to induce cravings. The results showed that “the strength of participants’ cravings was related to the vividness with which they imagined this scenario.”
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In other words, an effective use of visual-spatial working memory led to stronger feelings of cravings. Another study showed that cravings consumed attention, too, with participants not being able to perform a concurrent task as well when they were experiencing cravings as when they were not. Ironically, it is our human knack for keeping things in mind that works against us in compulsive
behaviors. Cravings would dissipate quickly if images could not be so readily maintained in human working memory.

JEALOUSY

In 1899, in the city of St. Louis, a young woman, Francis Baker, murdered her boyfriend, who was apparently cheating with another woman. The incident is immortalized in the popular song “Frankie and Johnny” written in the early twentieth century, and in a mural painted by Thomas Hart Benton, which still hangs in the House Lounge of the Missouri State Capitol in Jefferson City. More than one hundred years later, Clara Harris became known as the “Mercedes murderer” for running over her husband multiple times with a car after discovering him at a hotel with a mistress. In the
American Scientist
, Christine Harris recounted these historic murders as illustrative of the intensity of jealousy, noting that sexual betrayal is a relatively common reason for intentional homicide, usually turning up in the top three motives.
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Men more commonly murder their wives or girlfriends than the reverse, but this does not seem to be due to men being more likely than women to be incited to murder by jealousy. Rather, it stems from the simple fact that males commit more violent crimes of all types. In a comparison of homicides committed by men and women in six different cities in the United States plus five other countries (Africa, Canada, India, Poland, and Scotland), jealousy turned out to be as likely a motive for women as for men.
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Jealousy is a powerful emotional signal from the limbic system. Seeing one's love interest interact with a potential romantic rival can trigger an aversive emotional state. When the threat posed by a rival is seen as real and serious, the intensity of jealous feelings—a strange blend of fear and anger and betrayal and sadness, all rolled into one monstrous mess—can reach extremes. In the morbidly jealous, those feelings come with a full-blown delusion that their mate is cheating despite little, if any, objective evidence of infidelity. Morbid jealousy is “frequently accompanied by anger, depression, and urges to check up on and spy on…mates.”
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Even in cases where jealousy has not reached the level of delusion and clinical abnormality, it can nonetheless prompt rage leading to assaults and even murder.

Jealousy highlights the importance of the interpreter in human emotion. A male directing his gaze steadily at another attractive woman can arouse some degree of jealousy in his female partner. A flirtatious conversation between his wife or girlfriend and another good-looking man can do the same in a male. The explanations generated for these observed events, and the inner dialogue that ensues, determines the degree to which jealousy is aroused. Christine Harris has argued that

the primary appraisal of threat might be elicited by an input as simple as a positive interaction between the beloved and any potential rival (in sitcom terms, an act of gallantry or a sideways glance at a swinging skirt). Such an interaction between two others may elicit a vague sense of threat that does not have to be consciously assessed, may be innate and may occur in other animals. It functions to motivate actions that will break up the threatening liaison. At least in human adults, additional appraisals also come into play, including efforts to figure what the liaison implies for one's relationship and oneself. These appraisals affect both the intensity and direction of jealous feelings.
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Even in cases of normal jealousy, and certainly in cases of morbid jealousy, the interpreter is occupied by drawing inferences from minimal cues. The potential threats are unlimited in number and severity. Eye contact, smiling, and hugging are all normal forms of human social interaction that do not necessarily imply a threat of emotional or sexual betrayal. Yet they are also ways of flirting that may lead with time to infidelity. How these signs are interpreted determines whether jealousy is aroused as well as its degree of intensity.

Mental time travel also develops and shapes jealousy. Reconstruction of a past incident of flirtation can become distorted and blown out of proportion. As with other kinds of episodic memories, recollection is not necessarily veridical. If one is currently feeling jealous, then it can trigger reconstructions of past episodes that augment the feelings of anger and betrayal. Imagining future episodes of flirtation and infidelity comes equally easy because of our capacity for mental time travel. Fictitious rivals can be conjured in the imagination just as easily as real ones. Indeed, for the morbidly jealous individual, the imaginary rivals constitute much of the evidence for the delusional conviction that his or her mate is unfaithful.

The Great Wall of China was completed in the third century BCE as a defense against the nomadic warriors to the region's north. At two thousand miles in length, it symbolizes the “us versus them” mentality ingrained in the social circuitry of the human brain. We have a strong need to erect barriers between us and groups that we perceive as different, whether those differences are defined by the shade of skin color, the texture of hair, the shape of facial features, the clothing worn, the food eaten, or even the utensils by which food is eaten. Ethnicity and culture have always divided us as a species, and the social mind cannot be plumbed without diving straight into this history of divisiveness.

Yet, at the same time, it is equally true that human beings cannot live in isolation from one another. John Donne immortalized our dependence on each other, writing, “No man is an island, entire of itself; every man is a piece of the continent, a part of the main.”
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Indeed, our self-concept—the central organizing structure of semantic memory—is defined in large measure by how the self fits into not one but many groups of other human beings. Social identification starts in the immediacy of one's nuclear family and close friends, but it extends further into far larger groups. Imagine a set of concentric circles radiating outward, encompassing larger and larger sets of people. A person is a member of a family, an extended family, perhaps several organizations in one's local community (e.g., a neighborhood, a church, a school, a service organization), a town, a city or greater metropolitan area, a state, and a country. Ultimately, we are all citizens of planet earth, but the immense size of this group—more than seven billion—seems too large and abstract for the human
mind to readily grasp. The ties that bind us as fellow voyagers on a planet around the sun, all with the same utter dependency on the earth's capability to sustain human life, are regrettably fragile. When push comes to shove, people regard the needs of their country, their city, or their family as more pressing than the needs of humanity as a whole. The need to belong with others is part of the fundamental design of the human mind. “I'm with them” is stated loudly and clearly in what we say, what we wear, and how we behave.

Thus, the neural circuitry of affiliation with others and need for unity is as much a part of the social mind as the divisions and prejudice that can separate “us” from “the other.” In a way, they are two sides of the same coin. People stress their similarities to other members of their group while at the same time noting their differences with other groups. In so doing, they sharpen the category boundary between “us” and “them.” As would be expected by the out-of-Africa hypothesis of a common origin for modern human beings, there is considerable overlap in the gene pools of human populations around the globe. By far, the greatest degree of variability in the human genome lies within populations that are thought about as constituting single ethnic or racial groups. What follows is a thought experiment that illustrates the point that most variations among all individuals in the world can be found within any single population:

Suppose a grand catastrophe occurred (e.g., a large asteroid struck Earth) that resulted in the extinction of all of humanity except for a population of Eskimos living in the Arctic Circle. After many years, this population expands and migrates to eventually resettle the entire planet. From such limited origins, humanity would now have fully 85% to 95% of its pre-cataclysmic genetic diversity. People on different corners of the planet may look more similar to one another than they did before the calamity, but the genes for visible morphology are only a very small—and inconsequential—part of the totality of human diversity.
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Although the features of human physiognomy are trivial in the context of the genome, they are readily perceived and highly accessible to thought. So, it is hardly surprising that racial groups are deeply grounded in our psychology, if not our biology. The human social mind categorizes, ranks, and judges other
human beings on the basis of surface appearance. Images of how a person looks can be maintained in the visual-spatial stores of working memory and reflected upon in relation to language and behavior. Ethnic differences in language, religion, politics, dressing, housing, and eating divide groups of human beings in tandem with the visible features of the face and body. By contrast, the shared genomic commonality of different ethnic populations is not so easily perceived, thought about, and remembered. It is known to us only as an abstract concept from a complex scientific discipline. And, even then, this knowledge has been disseminated only briefly, since the time that the human genome was first deciphered and comparisons were made of different world populations.

GROUPS

People, regardless of their geographic location and culture, belong to groups of other human beings. Although the world population is now staggering in size, measured in the billions, the day to day interactions of human beings are confined to relatively small groups of people. Human beings—with the rare exceptions of hermits—seek out associations with others in their work and in their leisure. Face-to-face interactions, joint activities, and conversations take place on a periodically recurring, if not daily, basis. With social networks now available via the Internet, these linkages with others are less geographically constrained.

The psychological importance of the bonds we share with others can be seen when they must be broken. Breaking up an established relationship is highly distressing to human beings, and this fact is again universal across different cultures and different age groups. Although this is most obviously true of romantic relationships, it is also true of other friendships. For example, consider the resistance that friends have in separating, such as when graduating from school or moving to a different city:

As such transitions approach, people commonly get together formally and informally and promise to remain in contact, to share meals or other social occasions together, to write and call each other, and to continue the relationship
in other ways. They also cry or show other signs of distress over the impending separation…. Reunions constitute an occasion for people to see former acquaintances. The massive exchange of greeting cards during the Christmas holiday season includes many cases in which the card is the sole contact two people have had in the entire year, but people still resist dropping each other's name from the mailing list because to do so signifies a final dissolution of the social bond.
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Although we resist breaking social bonds with others, there are times when we are excluded regardless of our desire to continue the relationship. Being dumped by one's partner in a romantic relationship can be an intensely agonizing experience. The depression brought on by such rejection is convincing evidence of the centrality of our need for belonging and acceptance. One might wonder, however, if the person who rejects the love of another is somehow above this fundamental need. The answer seems to be negative. Typically, romantic relationships dissolve because the rejecter finds his or her partner unattractive or incompatible in some manner and unable to satisfy the desire for a close relationship. Or the rejecter has already satisfied this need with another preferred partner. Even in these cases, the rejecter often experiences feelings of guilt and empathy at the pain he or she has caused by breaking off the relationship.
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Cognitive neuroscientists have investigated the brain circuits that underlie social rejection. Intriguingly, the distress felt when excluded from others triggers the same system that mediates the perception of physical pain.
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The anterior cingulate cortex (ACC) is part of the neural circuitry for the executive attention component of working memory. A key function of this neural region is to monitor for conflicts in cognition and emotion. For example, when two cognitive representations are simultaneously active but call for actions that are diametrically opposed (e.g., go left and go right), the ACC detects this conflict. It acts, in other words, as an alarm system that informs the rest of the brain that something is wrong and needs attention. The dorsal portion of the ACC is known to signal perhaps the most primitive kind of alarm in the form of physical pain felt in the body. Pain is the brain's way of making sure one is aware that something is wrong with the body and that our attention is required. Just as physical pain is important for our survival, could it be that
the dorsal ACC also is activated when social attachments are disrupted. To the extent that our need to belong with others is fundamental to our security and survival, it makes sense that the social-attachment system might co-opt the existing physical-pain system.

To study social exclusion in the lab, psychologists had college students play a simple game of catch on a computer.
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The game is called
CyberBall and the participant's avatar plays catch with the avatars of supposedly two other people in the game. In actuality, the other two avatars are controlled by the computer rather than by people. The game starts out well, with the ball being tossed back and forth amiably among all three participants for seven throws. But then the real participant is excluded from the game for the remaining forty-five throws. The other two avatars hog the ball and never toss it back to the real participant. The fMRI scans taken during this exclusion period revealed a high degree of activation of the dorsal ACC. Another region was also found especially active during social exclusion, namely, the right ventral prefrontal cortex. This is of interest because this same region seems to mediate reductions in the perception of pain caused through a placebo effect, when people gain relief simply because they believe a pill is a pain killer. Presumably this prefrontal region is brought into play to inhibit the distress felt by social exclusion and to dampen the warning signals emitting from the ACC.

Family and friends in our closest social groups provide a means for coping with the everyday ups and downs of life, as well as with the more severe major life events of job loss, family deaths, and accidents. Fight or flight is the well-known response to stressors in life. Far less well-known is our need to belong and draw strength from close social relationships. Along with fight or flight, human beings also tend and befriend. A friend can be trusted with one's deepest thoughts and feelings, and can be a source of support on par with the first attachment of mother to child. Shelley E. Taylor has argued that “under conditions of stress, tending to offspring and affiliating with others (‘befriending’) are at least as common responses to stress in humans as fight-or-flight.”
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That human beings turn to one another during times of difficulty provides a compelling illustration of how important social connectedness is for our species. When positive social relationships are ruptured the brain triggers
both a neurohormonal response—elevation of oxytocin—and a social-behavioral response—elevation of seeking affiliations.
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Oxytocin, as well as the general reward system involving dopamine and opioids, serves to reinforce successful social contacts with others. Stress is directly reduced by tending and befriending, eliminating the problem that triggered the chain of events in the first place. On the other hand, what if others reject one's attempts to affiliate? Such negative social contacts will only worsen the stress, with negative consequences for health and well-being.

The need to belong would appear to be a genetically encoded result of our evolutionary history. It makes sense that human beings could best survive and reproduce in groups. There would be several advantages:

Groups can share food, provide mates, and help care for offspring (including orphans). Some survival tasks, such as hunting large animals or maintaining defensive vigilance against predatory enemies, are best accomplished by group cooperation. Children who desired to stay together with adults (and who would resist being left alone) would be more likely to survive until their reproductive years than other children because they would be more likely to receive care and food as well as protection.
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Human beings by nature seek to belong to social groups and to form long-term relationships with others. People are motivated to maintain social relationships and try to avoid needlessly breaking them off. When under stress, tending to these relationships provides a means for coping. Finally, rejection by others even invokes pain in regions of the brain that also mediate the perception of physical pain.

The human need to belong was very likely shaped and constrained by our advanced working memory ability and by language. In the social domain, working memory is needed to keep track of all the individuals with whom one has a relationship. The number of these relationships that can be successfully monitored and maintained would depend on the capacity of working memory and in particular on executive attention. It turns out that a form of the encephalization quotient that takes into account the size of the brain relative to body size is a good predictor of the typical group size favored by various species. That is to say, the volume of the neocortex relative to the volume of
the brain stem predicts the size of the group that can be effectively monitored.
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Because of our neocortex, especially with respect to the prefrontal cortex mediating the executive functions of working memory, human beings can monitor relationships in fairly large groups. Based on our neocortex ratio, a group size of nearly 150 is expected, and “there is considerable evidence that groupings of this size occur frequently in modern and historical human societies.”
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This is a relatively large group size compared with other primates with much smaller neocortex ratios. These nonhuman primates maintain social relationships through grooming each other. By contrast, human beings can use language to achieve the same purpose. By sharing information through language, interpersonal relationships and the cohesion of the group can be preserved. Thus, our unique ability to use language possibly allowed for larger group sizes than could reasonably be maintained through social grooming. Conceivably, “a form of social interaction that was more efficient than grooming in its use of time would thus have been required to facilitate the cohesion of such large groups.”
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