In-Groups and Out-Groups - The Social Unconscious

Subliminal: how your unconscious mind rules your behavior - Leonard Mlodinow 2013

In-Groups and Out-Groups
The Social Unconscious

All groups … develop a way of living with characteristic codes and beliefs. —GORDON ALLPORT

THE CAMP WAS in a densely wooded area in southeastern Oklahoma, about seven miles from the nearest town. Hidden from view by heavy foliage and ringed by a fence, it was situated in the midst of a state park called Robbers Cave. The park got its name because Jesse James had once used it as a hideout, and it was still an ideal place to hole up if being left undisturbed was a priority. There were two large cabins inside the perimeter, separated by rough terrain and out of sight and hearing both from any road and from each other. In the 1950s, before cell phones and before the Internet, this was enough to ensure their occupants’ isolation. At ten-thirty on the night of the raid, the inhabitants of one of those cabins darkened their faces and arms with dirt, then quietly made their way through the forest to the other cabin and, while its occupants slept, entered through the unlocked door. The intruders were angry and out for revenge. They were eleven years old.

For these kids, revenge meant ripping the mosquito netting off the beds, yelling insults, and grabbing a prized pair of blue jeans. Then, as their victims awoke, the invaders ran back to their own cabin as suddenly as they had arrived. They’d intended to inflict insult, not injury. Sounds like nothing more than a typical story of summer camp gone awry, but this camp was different. As these boys played and fought, ate and talked, planned and plotted, a corps of adults was secretly watching and listening, studying their every move with neither their knowledge nor their consent.

The boys at Robbers Cave that summer had been enrolled in a pioneering and ambitious—and, by today’s standards, unethical—field experiment in social psychology.1 According to a later report on the study, the experimental subjects had been carefully chosen for uniformity. A researcher laboriously screened each child before recruiting him, surreptitiously observing him on the playground and perusing his school records. The subjects were all middle-class, Protestant, Caucasian, and of average intelligence. All were well-adjusted boys who had just completed the fifth grade. None knew any of the others. After targeting two hundred prospects, the researchers had approached their parents offering a good deal. They could enroll their son in a three-week summer camp for a nominal fee, provided they agreed to have no contact with their child throughout that period. During that time, the parents were told, the researchers would study the boys and their “interactions in group activities.”

Twenty-two sets of parents took the bait. The researchers divided the boys into two groups of eleven, balanced for height, weight, athletic ability, popularity, and certain skills related to the activities they would be engaging in at camp. The groups were assembled separately, not told of each other’s existence, and kept isolated during their first week. In that week, there were really two boys’ camps at Robbers Cave, and the boys in each were kept unaware of the other.

As the campers engaged in baseball games, singing, and other normal camp activities, they were watched closely by their counselors, who in reality were all researchers studying them and secretly taking notes. One point of interest to the researchers was whether, how, and why each collection of boys would coalesce into a cohesive group. And coalesce they did, each group forming its own identity, choosing a name (the Rattlers and the Eagles), creating a flag, and coming to share “preferred songs, practices and peculiar norms” that were different from those of the other group. But the real point of the study was to investigate how and why, once the groups had coalesced, they would react to the presence of a new group. And so, after the first week, the Rattlers and the Eagles were introduced to each other.

Films and novels depicting either the distant past or the postapocalyptic future warn that isolated groups of Homo sapiens should always be approached with care, their members more likely to cut off your nose than offer you free incense. The physicist Stephen Hawking once famously endorsed that view, arguing that it would be better to beware of aliens than to invite them in for tea. Human colonial history seems to confirm this. When people from one nation land on the shores of another with a far different culture, they may say they come in peace, but they soon start shooting. In this case, the Rattlers and Eagles had their Christopher Columbus moment at the start of the second week. That’s when an observer-counselor separately told each group of the other’s existence. The groups had a similar reaction: let’s challenge the other to a sports tournament. After some negotiations, a series of events was arranged to take place over the following week, including baseball games, tug-of-war matches, tent-pitching contests, and a treasure hunt. Camp counselors agreed to provide trophies, medals, and prizes for the winners.

It didn’t take long for the Rattlers and the Eagles to settle into the dynamics of the countless other warring factions that had preceded them. On the first day of competition, after losing at tug-of-war, the Eagles, on their way back to their cabin, happened by the ball field where the Rattlers had hung their flag high up on the backstop. A couple of Eagles, agitated about getting beaten, climbed up and took it down. They set it on fire, and when the fire went out, one of them climbed back up and rehung it. The counselors had no response to the flag burning, except to dutifully and surreptitiously take their notes. And then they arranged the next meeting of the members of the two groups, who were told that they would now compete at baseball and other activities.

After breakfast the following morning, the Rattlers were taken to the ball field, where, while they waited for the Eagles to arrive, they discovered their burnt flag. The researchers watched as the Rattlers plotted their retaliation, which resulted in a mass brawl when the Eagles did show up. The staff observed for a while, then intervened to stop the fighting. But the feud continued, with the Rattlers’ raid on the Eagles’ cabin the next night, and other events in the days that followed. The researchers had hoped that by setting up groups with competitive goals but no inherent differences, they could observe the generation and evolution of derogatory social stereotypes, genuine intergroup hostility, and all the other symptoms of intergroup conflict we humans are known for. They were not disappointed. Today, the boys of Robbers Cave are past retirement age, but the tale of their summer, and the researchers’ analysis of it, is still being cited in the psychological literature.

Humans have always lived in bands. If competing in a tug-of-war contest generated intergroup hostility, imagine the hostility between bands of humans with too many mouths to feed and too few elephant carcasses to dine on. Today we think of war as being at least in part based on ideology, but the desire for food and water is the strongest ideology. Long before communism, democracy, or theories of racial superiority were invented, neighboring groups of people regularly fought with and even massacred each other, inspired by the competition for resources.2 In such an environment, a highly evolved sense of “us versus them” would have been crucial to survival.

There was also a sense of “us versus them” within bands, for, as in other hominid species, prehistoric humans formed alliances and coalitions inside their own groups.3 While a talent for office politics is useful in the workplace today, twenty thousand years ago group dynamics might determine who got fed, and the human resources department might have disciplined slackers with a spear through the back. So if the ability to pick up cues that signal political allegiances is important in contemporary work, in prehistoric times it was vital, for the equivalent of being fired was being dead.

Scientists call any group that people feel part of an “in-group,” and any group that excludes them an “out-group.” As opposed to the colloquial usage, the terms “in-group” and “out-group” in this technical sense refer not to the popularity of those in the groups but simply to the us-them distinction. It is an important distinction because we think differently about members of groups we are part of and those in groups we are not part of, and, as we shall see, we also behave differently toward them. And we do this automatically, regardless of whether or not we consciously intend to discriminate between the groups. In the last chapter I talked about how putting other people into categories affects our assessment of them. Putting ourselves into in- and out-group categories also has an effect—on the way we see our own place in the world and on how we view others. In what follows we’ll learn what happens when we use categorization to define ourselves, to differentiate “us” from others.

WE ALL BELONG to many in-groups. As a result, our self-identification shifts from situation to situation. At different times the same person might think of herself as a woman, an executive, a Disney employee, a Brazilian, or a mother, depending on which is relevant—or which makes her feel good at the time. Switching the in-group affiliation we’re adopting for the moment is a trick we all use, and it’s helpful in maintaining a cheery outlook, for the in-groups we identify with are an important component of our self-image. Both experimental and field studies have found, in fact, that people will make large financial sacrifices to help establish a feeling of belonging to an in-group they aspire to feel part of.4 That’s one reason, for example, that people pay so much to be members of exclusive country clubs, even if they don’t utilize the facilities. A computer games executive once shared with me a great example of the willingness to give up money for the prestige of a coveted in-group identity. One of his senior producers marched into his office after finding out that he had given another producer a promotion and raise. He told her he couldn’t promote her for a while yet, because of financial constraints. But she was insistent on being given a raise, now that she knew her colleague had gotten one. It was tough for this executive because his business was ultracompetitive, and other companies were always hovering in the background looking to steal good producers, yet he didn’t have the funds to hand out raises to all who deserved them. After discussing the matter for a while, he noticed that what really bothered his employee was not the lack of a raise but that the other producer, who was junior to her, now had the same title. And so they agreed on a compromise: he would promote her and give her a new title now, but the raise would come later. Like the country club sales office, this executive had awarded her a high-status in-group membership in exchange for money. Advertisers are very much attuned to that dynamic. That’s why, for example, Apple spends hundreds of millions of dollars on marketing campaigns in an attempt to associate the Mac in-group with smarts, elegance, and hipness, and the PC in-group with loser qualities, the opposites of those.

Once we think of ourselves as belonging to an exclusive country club, executive rank, or class of computer users, the views of others in the group seep into our thinking, and color the way we perceive the world. Psychologists call those views “group norms.” Perhaps the purest illustration of their influence came from the man who engineered the Robbers Cave study. His name was Muzafer Sherif. A Turk who immigrated to America for graduate school, Sherif earned his PhD from Columbia University in 1935. His dissertation focused on the influence of group norms on vision. You’d think vision would arise through an objective process, but Sherif’s work showed that a group norm can affect something as basic as the way you perceive a point of light.

In his work, decades ahead of its time, Sherif brought subjects into a dark room and displayed a small illuminated dot on a wall. After a few moments, the dot would appear to move. But that was just an illusion. That appearance of motion was the result of tiny eye movements that caused the image on the retina to jiggle. As I mentioned in Chapter 2, under normal conditions the brain, detecting the simultaneous jiggling of all the objects in a scene, corrects for this jiggling, and you perceive the scene as motionless. But when a dot of light is viewed without context the brain is fooled and perceives the dot as moving in space. Moreover, since there are no other objects for reference, the magnitude of the motion is open to a wide degree of interpretation. Ask different people how far the dot has moved and you get widely different answers.

Sherif showed the dot to three people at a time and instructed them that whenever they saw the dot move, they should call out how far it had moved. An interesting phenomenon occurred: people in a given group would call out different numbers, some high and some low, but eventually their estimates would converge to within a narrow range, the “norm” for that group of three. Although the norm varied widely from group to group, within each group the members came to agree upon a norm, which they arrived at without discussion or prompting. Moreover, when individual group members were invited back a week later to repeat the experiment, this time on their own, they replicated the estimates arrived at by their group. The perception of the subjects’ in-group had become their perception.


SEEING OURSELVES AS a member of a group automatically marks everyone as either an “us” or a “them.” Some of our in-groups, like our family, our work colleagues, or our bicycling buddies, include only people we know. Others, like females, Hispanics, or senior citizens, are broader groups that society defines and assigns traits to. But whatever in-groups we belong to, they consist by definition of people we perceive as having some kind of commonality with us. This shared experience or identity causes us to see our fate as being intertwined with the fate of the group, and thus the group’s successes and failures as our own. It is natural, then, that we have a special place in our hearts for our in-group members.

We may not like people in general, but however little or much we like our fellow human beings, our subliminal selves tend to like our fellow in-group members more. Consider the in-group that is your profession. In one study, researchers asked subjects to rate the likability of doctors, lawyers, waiters, and hairdressers, on a scale from 1 to 100.5 The twist was, every subject in this experiment was him- or herself either a doctor, a lawyer, a waiter, or a hairdresser. The results were very consistent: those in three of the four professions rated the members of the other professions as average, with a likability around 50. But they rated those in their own profession significantly higher, around 70. There was only one exception: the lawyers, who rated both those in the other professions and other lawyers at around 50. That probably brings to mind several lawyer jokes, so there is no need for me to make any. However, the fact that lawyers do not favor fellow lawyers is not necessarily due to the circumstance that the only difference between a lawyer and a catfish is that one is a bottom-feeding scavenger and the other is a fish. Of the four groups assessed by the researchers, lawyers, you see, form the only one whose members regularly oppose others in their own group. So while other lawyers may be in a given lawyer’s in-group, they are also potentially in his or her out-group. Despite that anomaly, research suggests that, whether with regard to religion, race, nationality, computer use, or our operating unit at work, we generally have a built-in tendency to prefer those in our in-group. Studies show that common group membership can even trump negative personal attributes.6 As one researcher put it, “One may like people as group members even as one dislikes them as individual persons.”

This finding—that we find people more likable merely because we are associated with them in some way—has a natural corollary: we also tend to favor in-group members in our social and business dealings, and we evaluate their work and products more favorably than we might otherwise, even if we think we are treating everyone equally.7 For example, in one study researchers divided people into groups of three. Each group was paired with another, and then each of the paired groups was asked to perform three varied tasks: to use a children’s toy set to make a work of art, to sketch a plan for a senior housing project, and to write a symbolic fable that imparts a moral to the reader. For each task, one member of each group in the pair (the “nonparticipant”) was separated from his or her cohorts, and did not take part in the tasks. After each pair of groups had completed a task, the two nonparticipants were asked to rate the results of the efforts of both groups.

The nonparticipants had no vested interest in the products their in-group had turned out; nor had the groups been formed with regard to any distinctive shared qualities. If the nonparticipants had been objective, therefore, you’d think that on average they would have preferred the products of their out-group just as often as they preferred those of their in-group. But they didn’t. In two cases out of three, when they had a preference, it was for what their in-group had produced.

Another way the in- and out-group distinction affects us is that we tend to think of our in-group members as more variegated and complex than those in the out-group. For example, the researcher conducting the study involving doctors, lawyers, waiters, and hairdressers asked all of his subjects to estimate how much those in each profession vary with regard to creativity, flexibility, and several other qualities. They all rated those in the other professions as significantly more homogeneous than those in their own group. Other studies have come to the same conclusion with regard to groups that differ by age, nationality, gender, race, and even the college people attended and the sorority women belonged to.8 That’s why, as one set of researchers pointed out, newspapers run by the predominantly white establishment print headlines such as “Blacks Seriously Split on Middle East,” as if it is news when all African Americans don’t think alike, but they don’t run headlines like “White People Seriously Split on Stock Market Reform.”9

It might seem natural to perceive more variability in our in-groups because we often know their members better, as individuals. For instance, I know a great many theoretical physicists personally, and to me they seem to be quite a varied bunch. Some like piano music; others prefer the violin. Some read Nabokov; others, Nietzsche. Okay, maybe they’re not that varied. But now suppose I think of investment bankers. I know very few of those, but in my mind I see them as even less varied than theoretical physicists: I imagine they all read only the Wall Street Journal, drive fancy cars, and don’t listen to music at all, preferring to watch the financial news on television (unless the news is bad, in which case they just skip it and pop open a $500 bottle of wine). The surprise is that the feeling that our in-group is more varied than our out-group does not depend on having more knowledge of our in-group. Instead, the categorization of people into in-groups and out-groups alone is enough to trigger that judgment. In fact, as we’ll see in just a bit, our special feelings toward our in-group persist even when researchers artificially sort strangers into random in-groups and out-groups. When Mark Antony addressed the throngs after Caesar’s assassination, saying, in Shakespeare’s version of the events, “Friends, Romans, countrymen, lend me your ears,” he was really saying, “In-group members, in-group members, in-group members …” A wise appeal.

A FEW YEARS ago, three Harvard researchers gave dozens of Asian American women at Harvard a difficult math test.10 But before getting them started, the researchers asked them to fill out a questionnaire about themselves. These Asian American women were members of two in-groups with conflicting norms: they were Asians, a group identified with being good at math, and they were women, a group identified as being poor at it. One set of participants received a questionnaire asking about what languages they, their parents, and grandparents spoke and how many generations of their family had lived in America. These questions were designed to trigger the women’s identity as Asian Americans. Other subjects answered queries about coed dormitory policy, designed to trigger their identity as women. A third group, the control group, was quizzed about their phone and cable TV service. After the test, the researchers gave the participants an exit survey. Measured by the subjects’ self-reports in that exit questionnaire, the initial questionnaire had had no impact on their conscious assessment of either their ability or the test. Yet something had clearly affected them subliminally, because the women who had been manipulated to think of themselves as Asian Americans had done better on the test than did the control group, who, in turn, had done better than the women reminded of their female in-group. Your in-group identity influences the way you judge people, but it also influences the way you feel about yourself, the way you behave, and sometimes even your performance.

We all belong to multiple in-groups, and, like the groups Asian Americans and women, they can have conflicting norms. I’ve found that once we are conscious of this, we can use it to our advantage. For example, I occasionally smoke a cigar, and when I do I feel a certain in-group kinship with my best friend in college, my PhD adviser, and Albert Einstein, all fellow physicists who liked their cigars. But when I think my smoking is getting dangerously out of hand, I find I can kill the urge quickly by coaxing myself to focus instead on another in-group of smokers, one that includes my father, who suffered from lung problems, and my cousin, who had debilitating mouth cancer.

The conflicting norms of our in-groups can at times lead to rather curious contradictions in our behavior. For example, from time to time, the media will broadcast public service announcements aimed at reducing petty crimes like littering and pilfering relics from national parks. These ads often also decry the alarming frequency with which these crimes occur. In one such ad, a Native American dressed in traditional garb canoes across a debris-ridden river. After the Native American reaches the heavily littered opposite shore, a driver—John Q. Public—zooms down an adjacent road and tosses trash out of his car, strewing garbage at the Native American’s feet. The ad cuts to a close-up, showing a lone teardrop running down the man’s face. That ad explicitly preaches an anti-litter message to our conscious minds. But it also conveys a message to our unconscious: those in our in-group, our fellow parkgoers, do litter. So which message wins out, the ethical appeal or the group norm reminder? No one studied the effects of that particular ad, but in a controlled study done on public service announcements, another ad that simply denounced littering was successful in inhibiting the practice, while a similar ad that included the phrase “Americans will produce more litter than ever!” led to increased littering.11 It’s doubtful that anyone consciously interpreted “Americans will produce more litter than ever!” as an order rather than a criticism, but by identifying littering as a group norm, it had that result.

In a related study, researchers created a sign condemning the fact that many visitors steal the wood from Petrified Forest National Park.12 They placed the sign on a well-used pathway, along with some secretly marked pieces of wood. Then they watched to see what effect the sign would have. They found that in the absence of a sign, souvenir hunters stole about 3 percent of the wood pieces in just a ten-hour period. But with the warning sign in place, that number almost tripled, to 8 percent. Again, it is doubtful that many of the pilferers literally said to themselves, Everyone does it, so why not me? But that seems to be the message received by their unconscious. The researchers pointed out that messages that condemn yet highlight undesired social norms are common, and that they invite counterproductive results. So while a college administration may think it is warning students when it says, “Remember! You must cut down on binge drinking, which is prevalent on campus!” what sinks in may instead be a call to action: Remember! Binge drinking is prevalent on campus! When, as a child, I tried to use my friend’s habits to justify, say, playing baseball on Saturday instead of going to the synagogue, my mother would say something like “So, if Joey jumped into a volcano, would you do it, too?” Now, decades later, I realize I should have said, “Yeah, Mom. Studies show that I would.”

I’VE SAID THAT we treat our in-groups and out-groups differently in our thinking, whether or not we consciously intend to make the distinction. Over the years, curious psychologists have tried to determine the minimal requirements necessary for a person to feel a kinship with an in-group. They have found that there is no minimal requirement. It is not necessary for you to share any attitudes or traits with your fellow group members, or even for you to have met the other group members. It is the simple act of knowing that you belong to a group that triggers your in-group affinity.

In one study, researchers had subjects look at images of paintings by the Swiss artist Paul Klee and the Russian painter Wassily Kandinsky and then indicate which they preferred.13 The researchers labeled each subject as either a Kandinsky fan or a Klee fan. The two painters had distinctive styles, but unless the subjects happened to be fanatic art historians specializing in early-twentieth-century avant-garde European painters, they probably had no reason to feel any particular warmth for those who shared their opinion. For the vast majority of people, on the passion scale, Klee versus Kandinsky was not exactly Brazil versus Argentina or fur coat versus cloth coat.

After labeling their subjects, the researchers did something that may appear odd. They, in essence, gave each subject a bucket of money and told them to divide it among the other subjects in any way they saw fit. The division was carried out in private. None of the subjects knew any of the other subjects, or could even see them during the course of the experiment. Still, when passing out the money, they favored their in-group, those who shared their group label.

A large body of research replicates the finding that our group-based social identity is so strong that we will discriminate against them and favor us even if the rule that distinguishes them from us is akin to flipping a coin. That’s right: not only do we identify with a group based on the flimsiest of distinctions, we also look at group members differently—even if group membership is unrelated to any relevant or meaningful personal qualities. That’s not just important in our personal lives; it also affects organizations. For example, companies can gain by fostering their employees’ in-group identification, something that can be accomplished by creating and making salient a distinctive corporate culture, as was done very successfully by companies such as Disney, Apple, and Google. On the other hand, it can be dicey when a company’s internal departments or divisions develop a strong group identity, for that can lead to both in-group favoritism and out-group discrimination, and research suggests that hostility erupts more readily between groups than between individuals.14 But regardless of what kind of shared identity does or doesn’t exist within a company, many companies find it effective to use marketing to foster a group identity among their customers. That’s why in-groups based on Mac versus PC ownership, or Mercedes versus BMW versus Cadillac, are more than just computer clubs or car clubs: we treat such categorizations as meaningful in a far broader realm than they have any right to be.

Dog person versus cat person. Rare meat versus medium. Powdered detergent versus liquid. Do we really draw broad inferences from such narrow distinctions as these? The Klee/Kandinsky study, and literally dozens more like it, followed a classic experimental paradigm invented by Henri Tajfel, who conducted the line-length experiment.15 In this paradigm, subjects were assigned to one of two groups. They were told that their group assignments had been made on the basis of something they shared with other members of the group but which, objectively speaking, was really quite meaningless as a way of affiliating with a group—either the Klee/Kandinsky preference or whether they had overestimated or underestimated the number of dots that were quickly flashed on a screen.

As in the study I quoted earlier, Tajfel allowed his subjects to dole out awards to their fellow subjects. To be precise, he had them give out points that could later be cashed in for money. The subjects did not know the identities of the people they were giving points to. But in all cases they knew the group to which the person belonged. In Tajfel’s original study, the handing out of points was a bit complicated, but the crux of the experiment lies in just the way it was done, so it is worth describing.

The experiment consisted of over a dozen stages. At each stage, a subject (“awarder”) had to make a choice regarding how to dole out points to two other subjects (“recipients”), who, as I said, were anonymous. Sometimes the two recipients were both members of the subject’s own group or both members of the other group; sometimes one was a member of the subject’s own group and the other was a member of the other group.

The catch was that the choices offered to awarders did not represent a zero-sum game. That is, they did not entail simply deciding how to divide a fixed number of points. Rather, the options offered added up to varying point totals, as well as differing ways of splitting those points among the two recipients. At each stage, the awarder had to choose from among over a dozen alternative ways to award points. If the awarders felt no in-group favoritism, the logical action would be to choose whichever alternative bestows upon the two recipients the greatest total number of points. But the awarders did that in only one circumstance: when they were dividing points among two members of their in-group. When awarding points to two members of the out-group, they chose options that resulted in awarding far fewer points. And what is really extraordinary is that when the options required awarders to divide points between one in-group member and one out-group member, they tended to make choices that maximized the difference between the rewards they gave to the two group members, even if that action resulted in a lesser reward for their own group member!

That’s right: as a trend, over dozens of individual reward decisions, subjects sought not to maximize their own group’s reward but the difference between the reward their group would receive and that which the other group would be awarded. Remember, this experiment has been replicated many times, with subject pools of all ages and many different nationalities, and all have reached the same conclusion: we are highly invested in feeling different from one another—and superior—no matter how flimsy the grounds for our sense of superiority, and no matter how self-sabotaging that may end up being.

You may find it discouraging to hear that, even when group divisions are anonymous and meaningless, and even at their group’s own personal cost, people unambiguously choose to discriminate in favor of their in-group, rather than acting for the greatest good. But this does not doom us to a world of never-ending social discrimination. Like unconscious stereotyping, unconscious discrimination can be overcome. In fact, though it doesn’t take much to establish grounds for group discrimination, it takes less than we think to erase those grounds. In the Robbers Cave experiment, Sherif noted that mere contact between the Eagles and the Rattlers did not reduce the negative attitude each group had for the other. But another tactic did: he set up a series of difficulties that the groups had to work together to overcome.

In one of those scenarios, Sherif arranged for the camp water supply to be cut off. He announced the problem, said its cause was a mystery, and asked twenty-five volunteers to help check the water system. In reality, the researchers had turned off a key valve and shoved two boulders over it and had also clogged a faucet. The kids worked together for about an hour, found the problems, and fixed them. In another scenario, Sherif arranged for a truck that was supposed to get food for the boys not to start. The staff member who drove the truck “struggled and perspired” and got the truck to make all sorts of noises, as more and more of the boys gathered around to watch. Finally the boys figured out that the driver might be able to start the truck if they could just get it moving. But the truck was on an uphill slope. So twenty of the boys, from both groups, tied a tug-of-war rope to the truck and pulled it until it started.

These and several other scenarios that gave the groups common goals and required cooperative intergroup actions, the researchers noted, sharply reduced the intergroup conflict. Sherif wrote, “The change in behavior patterns of interaction between the groups was striking.”16 The more that people in different traditionally defined in-groups, such as race, ethnicity, class, gender, or religion, find it advantageous to work together, the less they discriminate against one another.17

As one who lived near the World Trade Center in New York City, I experienced that personally on September 11, 2001, and in the months that followed. New York is called a melting pot, but the different elements tossed into the pot often don’t melt, or even blend very well with one another. The city is perhaps more like a stew made of diverse ingredients—bankers and bakers, young and old, black and white, rich and poor—that may not mingle and sometimes distinctly clash. As I stood beneath the north tower of the World Trade Center at 8:45 a.m. on that September 11, among the bustling crowd of immigrant street vendors, suited Wall Street types, and Orthodox Jews in their traditional garb, the city’s class and ethnic divisions were amply apparent. But at 8:46 a.m., as that first plane hit the north tower and chaos erupted, as the fiery debris fell toward us and a horrific sight of death unfolded above us, something subtle and magical also transpired. All those divisions seemed to evaporate, and people began to help other people, regardless of who they were. For a few months, at least, we were all first and foremost New Yorkers. With thousands dead, and tens of thousands of all professions, races, and economic status suddenly homeless, or jobless because their place of work had been shut down, and with millions of us in shock over what those in our midst had suffered, we New Yorkers of all kinds pulled together as I had never before experienced. As entire blocks continued to smolder, as the corrosive smell of the destruction filled the air we breathed, and as the photos of the missing looked down on us from buildings and lampposts, subway stations and cyclone fences, we showed a kindness to one another, in acts large and small, that was probably unprecedented. It was the best of our human social nature at work, a vivid exhibition of the positive healing power of our human group instinct.