The Making of the Mind: The Neuroscience of Human Nature (27 page)

Jerry Burger tested a sample of the general public in 2006, and 70 percent of subjects continued beyond the switch for 150 volts when they first heard the leaner protest, only slightly less than the 82 percent of those tested in 1961 and 1962.
¹⁰
Milgram reported that 65 percent of the volunteers in his original experiment complied with orders all the way to the top of the scale, the highly dangerous shock of 450 volts. To avoid the ethical problem of ordering participants to go that far, in the contemporary replication study participants were stopped if they attempted to exceed 150 volts. Still, it was
possible to extrapolate how many likely would have continued to the top of the scale. “Because 79% of Milgram's participants who went past this point continued to the end of the shock generator's range, reasonable estimates could be made about what the present participants would have done if allowed to continue. Obedience rates in the 2006 replication were only slightly lower than those Milgram found 45 years ago.”
¹¹
The power of the situation—an authority figure issuing orders to obey—can encourage us to skip the deliberative process needed to do the right thing. Although human beings are endowed with the modern mental ensemble that can lead to moral choices, a failure to engage these resources renders them moot.

The abstract reasoning processes enabled by our advanced working memory can be elicited in laboratory tasks that pose a moral dilemma, allowing the brain networks to be identified. Would you activate a switch that diverts the path of train so as to save five people if it meant killing one? Most people take a utilitarian view that the lives of five people outweigh the life of just one, so they would in fact divert the train to the track with only one person on it. Neuroimaging data revealed that this impersonal moral dilemma activated areas in the right middle frontal gyrus and the posterior parietal cortex associated with working memory and reasoning tasks in general.
¹²
These regions were affected no differently in the impersonal moral dilemma and a nonmoral decision task. However, by switching the task instructions just slightly to make the decision personal, the emotional areas of the brain were instead highly activated. Would you push a stranger off a bridge to save the lives of five others? The stranger will die as a result of your decision, but the stranger's body on the tracks will stop the train and thus save five others. In this scenario, bilateral activation of the medial frontal gyrus, the posterior cingulate gyrus, the angular gyrus predominated.
¹³
Not only are these regions involved in emotional processing, they also constitute the default network underlying mental time travel.
¹⁴
Imagining the future or recollecting the past requires the brain to simulate an experience that is not present here and now. Possibly the same kind of simulation must transpire before one can make a personal moral choice that is emotionally laden. One must actually imagine pushing the person off the bridge before a decision can be reached. By contrast, the impersonal moral dilemma can be tackled as a problem of cold reason.

MORAL INTUITIONS

Although reasoning on the basis of justice or care is fundamentally important to human morality, it is not the only basis for behavior. Moral intuitions that operate quickly, automatically, and without rational deliberation can also control behavior. Although deliberative reasoning is commonplace, it may be used by people “to seek evidence in support of their initial intuition and also to resolve those rare but difficult cases when multiple intuitions are possible.”
¹⁵
Jonathon Haidt makes the point that our intuitive moral judgments are tapped so quickly that they can bias the course of more deliberative reasoning.

Offensive foods, such as rotten meat, elicit strong feelings of disgust automatically. Disgust is readily elicited by pictures of “slimy, moist surfaces or colors reminiscent of body fluids” because they indicate the presence of pathogens that are dangerous to human health.
¹⁶
In a different way, disgust can also be powerfully elicited by morally taboo behaviors such as incest. It is immediately obvious to people that, say, having sex with a brother or sister is disgusting. Although the brain shows a common pathway in registering disgust to these two scenarios, they also differ in several ways. From neuroimaging data, researchers conclude that “despite their tendency to elicit similar ratings of moral disapproval, incest-related acts and non-sexual immoral acts entrain different, but overlapping brain networks.”
¹⁷

In these circumstances, the interpreter of the left hemisphere engages in the moral domain as it does in all domains. It tries to provide an explanation. An automatic intuition yields a judgment that the interpreter then tries to account for using all that is known about the current situation. For example, in making a moral judgment about a harmful act it is important to know the intention of the perpetrator. Did a man who shot his hunting partner do so by accident or on purpose? There is an obvious difference in our reprehension of the shooter depending on how we read his mind. The critical feature in our legal code between manslaughter and murder is whether a death results by accident or by intent. The advanced social intelligence of the human brain includes a network in the right inferior frontal cortex that aids this theory of mind skill.
¹⁸
In split-brain patients, the computations made in the right hemisphere about the intentions of an actor are not transmitted across the
corpus callosum as normally would occur. Thus, the left hemisphere of the split-brain patient cannot readily take into account the intentions of others in judging the moral probity of their actions.
¹⁹
Indeed, for split-brain patients the outcome—the perceived act—is all that matters in deciding right or wrong. An action is immoral if it led to a bad outcome regardless of whether the actor had no intention to harm. When asked why an innocent act that accidently caused harm is morally offensive, the left hemisphere of the split-brain patient concocts an explanation. As Michael Gazzaniga concluded from his studies on moral judgments in split brain patients, “the interpreter introduces a misleading level of certainty about the reasons that moral judgments are made. Yet the narrative of the interpreter helps us make sense of our social environment.”
²⁰

In normal individuals with an intact corpus callosum one can see the same effect through the use of hypnosis. The basic idea was to implant a posthypnotic suggestion that would elicit a strong feeling of disgust whenever a particular arbitrary word was read (i.e.,
often
). For highly hypnotizable individuals, it is possible to suggest that the individual feel something or do something later on when they come out of hypnosis, and they will reliably do so. Importantly, they will do so without any clear understanding of why. That is, they may not have a memory of having been told to feel disgust when reading
often
, but they will nonetheless feel disgust. The participants were presented with a variety of scenarios that varied in their offensiveness. At the high end was engaging in incest with a cousin. Bribery was not particularly disgusting, but it was viewed as morally wrong. The result showed that if the trigger word, such as
often
appeared in the description of the scenario, it heightened the feelings of disgust and the severity of judgments that the scenario is morally wrong. This outcome held for both bribery and incest.
²¹

Those in the experiment who were not aware that the posthypnotic suggestion was having this effect on their emotions and moral judgments were in much the same situation as the split-brain patients; or, in the shoes of us all when disgust is immediately and automatically registered before any reasoning can take place. In these circumstances, the left-brain interpreter plays a critical role of trying to account for why we feel and judge the way we do. In another hypnosis experiment, a perfectly innocent scenario was associated
with the trigger word.
²²
It described a student council representative who was put in charge of organizing discussions around topics of interest to both the students and faculty. Without the presence of the hypnotic trigger word, this story elicited neither disgust nor moral concerns. Yet with the trigger word, the student's actions were seen as nine times as disgusting and five times as morally wrong. To justify their odd reactions, the participants made up explanations: “It just seems like he's up to something,” or he is just “a popularity-seeking snob.”
²³
These views were not expressed when there was no posthypnotic trigger to feel disgust. As Michael Gazzaniga noted, “This behavior suggests that automatic social evaluation produces a judgment, which the interpreter then registers and attempts to explain.”
²⁴

EMPATHY

Human beings have an acutely developed capacity to comprehend and tend to the emotional experiences of others. If we observe sadness in another person, then we, too, can experience sadness; in the same way, happiness can be contagious and spread in a social group simply from observing the happiness of another. At a basic level of perception and action, empathy for the feelings of others involves the mimicry of facial expressions. We reflexively frown or smile to reflect the sadness or happiness seen in another. Yet empathy involves more than this perceptual-motor response to the feelings of others. It further invokes the high level of social intelligence that allows us to understand others as intentional agents with minds of their own. The rich set of theory-of-mind developments in early childhood build upon the more primitive emotional mimicry networks. Empathy further draws on the executive functions of our advanced working memory to take the perspective of another person and see the world from his or her eyes. Human empathy, then, represents a complex interaction of neural capacities that come together in a radically different way from other species.

A precursor to human empathy definitely has been found. The premotor cortex of primates possesses a special type of neurons, called mirror neurons because they appear to allow mimicry. In a macaque monkey, recordings of the firings of these neurons can be observed when the monkey grasps or
manipulates an object, but also when another monkey, or even a human experimenter, performs the same action.
²⁵
The mirror neurons in the ventral premotor cortex are part of a circuit that extends from the posterior parietal cortex, passing through the posterior superior temporal cortex. In seeing an action performed, the motor neurons that produce the same action are stimulated via this circuit.
²⁶
This requires a common code that couples perception and action. The way the brain codes for a particular action entails a representation of the perceivable effects of that action. In the case of perceiving an emotional expression of another monkey, the codes would be activated for producing that same expression and mimicking it. The mirror neurons and the network linking perception with action can thus provide a foundation for empathy, in the sense that one can catch the emotion experienced by another. Emotion contagion can be seen in human beings who viewed pictures of happy or angry faces for a very brief time, too fast for their conscious registration. Nevertheless, measurements of their facial muscles showed they were mimicking the happy or angry expressions presented. “Furthermore, this effect was stronger for the participants who scored higher on self-reports of empathy.”
²⁷

Psychologists have recognized various facets of empathy, starting with the fact that feelings are elicited by another person's emotional state.
²⁸
This can result in a sharing of the emotional state of another person, although it is also possible to empathize with another without sharing in the same emotion. A distance can be maintained, while still recognizing what the other person is feeling. Actually sharing in the emotional experience of another can occur in different ways. On the one hand, the emotional expressions of another person can automatically trigger the same expressions in us through mimicry. On the other hand, we can devote executive attention to imagining how the other person is feeling and thinking, in the metaphoric senses of stepping into their shoes or seeing the world with their eyes. Lastly, there is the self-regulation that underlies our ability to keep our distance, while still empathizing. Complete sharing of another's negative emotional state of, say, sadness, and complete adoption of another's point of view, could be personally distressing and even paralyzing. We would not be able to respond effectively to the emotional needs of others if we ourselves were to become too sad and depressed to act.

Regions in the prefrontal cortex mediate the executive function of taking
another person's perspective. Imagine a situation that would induce the emotion of shame. Now, imagine how you would feel in that situation? Finally, imagine how your mother would feel in the same situation. A neuroimaging study compared the shame-inducing situation with a control situation that was emotionally neutral. “Regardless of the affective content of the situations depicted, when the participants activated their mothers’ perspective, activation was detected in the frontopolar, ventromedial prefrontal, and medial prefrontal cortex, and the right inferior parietal lobule—congruent with the role of these regions in executive functions associated with the perspective taking process.”
²⁹
The theory-of-mind capabilities of our advanced social intelligence must be leveraged by the executive attention of our advanced working memory to pull off the feat of taking another person's perspective.

One study used functional magnetic resonance imaging (fMRI) to detect whether we literally can feel another's pain. Pictures of people with their hands or feet in painful situations were shown to research participants who were asked to rate the level of pain they vicariously experienced from viewing the pictures. When instructed to imagine themselves in this situation, participants reported feeling high levels of pain, and the fMRI results revealed that the anterior cingulate cortex and anterior insula were activated, just as they are when pain is actually experienced firsthand.
³⁰
The higher the activation of these areas, the more pain the participant reported would be produced. Similarly, these same regions fired when a participant received a painful stimulus. But they also fired when they then simply observed a partner receiving the same stimulus—the brain network was registering pain felt by another person, a precondition for empathy.