Much human behavior is social behavior, that is, behavior that occurs in interaction with other people. Let’s look at social behavior in three types of settings, ranging from large to small:

Would you kill someone to get a good seat at a concert? Your answer surely is no. How many of your friends would kill somebody to get a good seat at a concert? Your answer is probably zero. Who would kill someone just to get a good seat?

In Cincinnati in 1979, tragedy struck at a concert. Eleven people were killed by concertgoers trying to get a good seat for a show by the British rock band The Who.

How could this have happened? Were there 11 Who fans crazy enough to kill somebody to get a good seat? Was there one crazed murderer who needed seats for himself and 10 friends?

There is no evidence that the concert attracted any crazed murderers. It attracted normal people like yourself who wouldn’t choose to kill anybody; reports indicate that fans were “not riotous or violent” (The Who Concert Tragedy Task Force, 1980, p. 1). The culprit, then, was not any individual person. It was something bigger, with a force of its own: a crowd. The uncontrollable behavior of the crowd resulted in those 11 deaths.

Here is what happened. Seating at the concert was not reserved. Thousands of fans lined up ahead of time to get a good seat when the doors opened. There were few doors. As a result, a huge physical force, the crowd, propelled itself through a small physical space, the few doorways. “Rippling human waves of pressure knocked people down and rendered them helplessly trapped and fighting for breath” (http://www.crowdsafe.com/taskrpt/).

Unfortunately, this crowd disaster was not unique. About 2000 people a year die from being trapped in crowds (Hughes, 2003). Sometimes these tragedies are much larger in scope than the Who concert tragedy. In early 2006, roughly 1 million people were in Mecca, Saudi Arabia, for the Hajj, the annual Islamic pilgrimage. Crowding on a pedestrian bridge resulted in the death of 345 of these pilgrims, who were crushed, trampled, or suffocated (Murphy, 2006).

These tragedies teach us something important about people’s social behavior in crowds. The behavior cannot be explained in terms of the desires of the individual people in the crowd. No individual Who fan wanted to kill anybody. No individual person on the Hajj wanted anyone else to be trampled to death. The tragedies resulted from the action of the crowd as a whole.

How, then, can we begin to understand the force of the crowd as a whole? One way is to treat the crowd as a physical object.

THE PHYSICAL CROWD. People take up space. A big crowd of people thus requires a lot of space. If too big a crowd is crammed into too small a space, people can be squeezed so tightly that they will literally be unable to breathe. One way to understand the behavior of crowds and to avert crowd tragedies is to study the physical nature of crowds in tight spaces. This is what the government of Saudi Arabia concluded after the deaths of the 345 religious pilgrims in 2006.

When people watched videos of that tragedy, they saw that the crowding problem occurred at a very precise spot on the pilgrims’ path: a narrow “pinch point” (Murphy, 2006) on the overall route. Might the sheer physical force of the crowd at this particular point have caused the tragedy?

To find out, the Saudi government sought the advice of physicist Dirk Helbing (Helbing et al., 2014; Holden, 2007). In analyzing crowd flow through the physical layout of the Hajj route, Helbing developed an analogy: A human crowd is analogous to a fluid. Specifically, the flow of a crowd through walkways and bridges is like the flow of a liquid through trenches or pipes. Whether crowd flow is smooth or turbulent does not depend on the psychological characteristics of the individual people in the crowd. It depends on the rate of flow of the crowd as a whole and the space through which the crowd flows. If flow is too fast or the space is too small, flow—of a liquid or a human crowd—becomes turbulent.

The crowd-as-fluid approach enabled Helbing not only to identify turbulent spots on the Hajj route (e.g., narrow passages that did not allow for a consistently smooth flow of people), but also to redesign the route to eliminate the turbulence. He reconfigured walkways, barriers, and plazas to create more elongated spaces that reduced “bottlenecks” in the system. The Saudi government then reconstructed the Hajj route according to his plan, and the changes worked: The next year’s pilgrimage proceeded safely (Helbing, Johansson, & Al-Abideen, 2007) and there have been no Hajj crowding disasters since.

THE PSYCHOLOGY OF THE CROWD. Treating a crowd as a physical object—a giant flowing liquid—tells us only part of the story of crowds. Crowds aren’t only physical. They are also psychological. There might be a unique “psychology of the crowd.”

This possibility was addressed in one of the first works in the history of social psychology, by a nineteenth-century Frenchman, Gustave Le Bon (1896). Le Bon’s interests were both psychological and political. In nineteenth-century Europe, political power shifted from royal dynasties to the public. Although most of us today would applaud this, Le Bon was concerned. He believed that individuals, once gathered into crowds, would become unruly and violent. “Isolated,” Le Bon wrote, “[a person] may be a cultivated individual; in a crowd, he is a barbarian—that is, a creature acting by instinct” (Le Bon, 1896, p. 36).

About a half-century later, some American social psychologists proposed a similar theory (Festinger, Pepitone, & Newcomb, 1952). They suggested that people in a crowd lose their normal sense of self and act impulsively, failing to judge whether actions are right or wrong. Anonymity was thought to trigger impulsive, aggressive action. In a huge crowd, you’re anonymous, and that anonymity might cause you to disregard rules of civilized behavior (Zimbardo, 1970).

If you are thinking like a psychological scientist, you are skeptical. Just because Le Bon and others said that anonymity causes crowd violence does not mean their conclusion is correct; you need to consider research findings. As it turns out, quantitative and qualitative research findings (Chapter 2) highlight factors other than anonymity. Let’s look at the quantitative (numerical) data first.

Many researchers have measured levels of aggression displayed by participants in two types of experimental conditions. In one, participants are made anonymous (e.g., by dressing them in oversized coats with hoods). In the other, they are identifiable (they wear regular clothing and name tags). People in both conditions have the opportunity to act aggressively; for example, they may deliver electric shocks to people in another room (Zimbardo, 1970). A summary of 60 such experiments did not support the view that anonymity increases aggression (Postmes & Spears, 1998). Rather, results highlighted a different psychological factor: social norms.

A social norm is a socially shared belief about the type of behavior that is acceptable in any given setting. In almost any setting, some types of behavior are acceptable or “normative,” whereas others are not. At a funeral, the norm is quiet, somber behavior. At a party, carefree, sociable behavior is normative. Norms often are not stated explicitly; instead, you learn them by observing others. In crowds, people learn social norms by observing others who are near them; they respond to “norms in the immediate social context” (Postmes & Spears, 1998, p. 254). If people near you in a crowd of political protesters are cursing loudly at government officials, you learn that it is acceptable to curse loudly in this setting, and you may do so, too. Crowds, then, affect behavior by defining local social norms.

Qualitative data (information derived from interviews or written descriptions of behavior; Chapter 2) reveal a second cause of crowd violence, when it occurs. Some people in crowds intend to act violently. They do not lose their sense of self and ability to plan. Rather, they do plan—to be violent (McPhail, 1994). Consider an interview of a British soccer “hooligan” who took part in attacks on fans of a rival team. “I go to a [soccer] match for one reason only: the aggro [the opportunity to act aggressively],” he said. “It’s an obsession, I can’t give it up” (McPhail, 1994, p. 23). In an interview, one member of a Los Angeles gang said, “It’s going to be hard to bring [the violence] to an end. A lot of us been doing this for years and don’t want it to stop” (p. 24). Analysis of crowd behavior reveals that small groups of people who intend to act violently create much of the violence in a crowd (McPhail, 1994).

Think about how this finding conflicts with Le Bon’s explanation of crowd violence. Le Bon claimed that crowds cause peaceful people to become impulsively violent. But qualitative evidence shows that people who are not peaceful strategically choose to engage in violence in crowds.

CROWD RESPONSE TO DISASTER. Crowds often gather for a purpose: to hear a concert, cheer for the home team, or support a politician. Yet sometimes, people don’t intentionally gather at all. Instead, they are thrown together unexpectedly. People who previously had no shared purpose—who merely happened to be in the same place at the same time—suddenly can have a common purpose thrust upon them. This happens when disasters strike.

Many of us will never experience firsthand a disaster such as a plane crash, terrorist bombing, or natural catastrophe (earthquake, hurricane, etc.). Yet disasters are more common than you might think. An Internet service (http://hisz.rsoe.hu/alertmap/index.php?lang=eng) that details current disasters and emergencies worldwide lists, at the time of this writing, not just one or two disasters worldwide, but 15: 3 floods, 4 tropical storms or other cases of extreme weather, 5 disasters involving biological contaminants or the release of hazardous materials, 1 forest fire; 1 outbreak of an epidemic disease; and 1 explosion. How do people respond to such events?

One possibility is that they panic. Movies and TV programs sometimes show people responding to disasters by waving their hands in the air and screaming. Yet this is not what people usually do; evidence suggests that widespread panic is rare (Drury, 2004, p. 119). People usually follow instructions from authorities and help each other. Consider some examples:

Why do people so often respond to disasters by helping rather than panicking? A crowd thrown together by a disaster develops a sense of “shared identity” (Drury & Cocking, 2007, p. 4). The disaster reminds them of something they otherwise might forget: that they are part of the human family, their fate bound together with that of neighbors, coworkers, and even complete strangers. They recognize that they must pull together—and they usually do.

We now move from crowds to groups. This might not seem like much of a move, but it is. The psychological dynamics of crowds and groups differ.

Unlike crowds, the collections of people called groups generally know each other, communicate with one another, and share a common purpose. Group members often have well-defined responsibilities; one may be a leader, another an assistant to the leader, and still others may primarily follow the leader’s command. Group members may have different goals, creating conflict within the group. Some may hold opinions that differ from those of others in the group and feel pressure to change their opinions. These psychological processes involving communication, conflict, and pressure among group members are group dynamics.

Social psychologists try to understand how group dynamics influence the behavior of individuals in the group. Research addresses three types of group influence: conformity, compliance, and obedience.

CONFORMITY. Conformity occurs when people alter their behavior to match the norms of a group (Cialdini & Goldstein, 2004). If you show up for your first day at work wearing jeans but notice everybody else is wearing a suit, deciding to dress in a suit the next day would be conforming to the group of employees at work.

Classic research by social psychologist Solomon Asch (1955) shows the power of conformity. Participants, upon arriving at Asch’s laboratory, joined a small group of people taking part in an experiment that supposedly was about visual perception. Across a series of 18 trials, they were shown a “standard line” and three “comparison lines” and were asked to judge which comparison line was the same length as the standard (Figure 12.1). People expressed their judgments out loud; group members, one at a time, indicated which line they thought matched the standard line.

Had you participated in this experiment, you would have found the task easy. On the first trial, one line clearly matches the standard, whereas the other lines differ. The experimenter goes around the room and everyone gives the same answer. On the second trial, the same thing happens: The perceptual task is easy and everyone gives the same answer. But on the third trial, something strange happens. It looks to you, a participant, as if one line obviously matches the standard and the others do not. Yet the first person who responds gives an answer that seems wrong. You think the person just made a mistake. Then the next person gives the same wrong answer. One by one, everybody gives that same incorrect answer. Next it’s your turn. What do you do? “Stick to your guns” and give the answer you believe is right, or conform to the group and give the answer everyone else did?

Participants faced this dilemma on 12 of 18 trials. Each time, all other participants gave the same answer, but it plainly was wrong. Did participants conform, that is, give answers that matched those of others in the group?

Before learning the results, you need to know a key piece of information. The other people—the group members who gave the wrong answer—were accomplices of the experimenter (or experimental “confederates”; see Research Toolkit, on the next page). Asch scripted their responses, instructing them to answer incorrectly on 12 of the 18 trials. The real research participant, of course, thought the others were real participants, too.

Asch found that conformity—the degree to which people conformed to the opinions of the group—depended on two factors that he manipulated experimentally: group size and unanimity.

The second lesson about conformity is that group pressures for conformity are greatest when the group is unanimous. When in a group—even a small one—in which no one else’s opinions or behaviors match yours, you feel enormous pressure to conform.

Remarkably, conformity occurred in Asch’s study even though group members (1) did not explicitly ask the participant to conform (they merely voiced their own answers) and (2) were not in a position of authority with respect to the participant (they seemed merely to be other people who signed up for the study). Group pressures may increase when people make explicit requests or are in positions of authority, as you’ll see below.

RESEARCH TOOLKIT

Conformity pressures also are influential when groups come together to make a joint decision. Pressure for conformity can produce groupthink, a decision-making phenomenon in which group members are so motivated to avoid disagreement, and to reach a shared decision, that they do not properly evaluate the quality of the decision they are reaching (Esser, 1998). Case study research launched social psychology’s interest in groupthink. Irving Janis (1971) analyzed historical cases in which government officials made poor decisions, such as the Bay of Pigs decision in which the Kennedy administration invaded Cuba with a military force that was far too small for the task. Janis did not find that Kennedy administration officials were unintelligent. Rather, despite their high intelligence, groupthink produced a decision that was poor. Decision makers neglected critical information that conflicted with the most popular opinion in the group. As a result, their final decision was misguided and costly.

COMPLIANCE. Everyday life bombards us with requests: donate to our charity; learn about our candidate; complete our survey; try our new energy drink. Often you just say no. But sometimes, you find yourself saying yes. You donate, take some campaign materials, complete the survey, or try a free sample of the drink. If you do, your actions are cases of compliance, behavior in which individuals agree to an explicit request.

Social psychologists have identified techniques that increase compliance. One method is the foot-in-the-door technique.

The foot-in-the-door technique is a compliance strategy in which someone first makes a small request, in order later to convince people to comply with a larger request. The initial request is so small that almost everyone will agree to it; the small request gets your “foot in the door.” Once you’re “in,” compliance with a big request is more likely. In one study (Freedman & Fraser, 1966/1971), the small request was an appeal to homeowners to sign a “safe driving” petition. The request was so simple that almost everyone agreed. A couple of weeks later, experimenters visited the homes of these people, plus a second group who had not been contacted about the petition. On the visit, the experimenters made a big request: to install a large “drive carefully” sign on their front lawn—a sign so big that workmen would have to dig a hole for a post to hold it. Who’d ever agree to that? People who had previously signed the “foot-in-the-door” petition would! A majority of them agreed to have the sign installed. Among people who had not signed the petition, more than four out of five people refused to have the sign installed. Subsequent research confirms that foot-in-the-door enhances compliance (Burger, 1999; Cialdini & Goldstein, 2004).

Why is foot-in-the-door so effective? It can change the way people think about themselves. For example, after signing the petition, people may feel personally involved in the cause of safe driving. This sense of personal involvement increases later compliance (Freedman & Fraser, 1966/1971).

Another compliance strategy uses distraction. When asked to comply with a request, people often have two reactions in sequence: (1) positive feelings about the request, because it supports a good cause, and (2) negative thoughts about it, because it requires an expenditure of time or money. The disrupt-then-reframe technique (Davis & Knowles, 1999) increases compliance by distracting people, so they cannot formulate any negative thoughts. In one demonstration of the technique, researchers conducted door-to-door sales of $3 boxes of Christmas cards for a purportedly good cause; profits went to charity. In one experimental condition, researchers said, “They’re $3. It’s a bargain.” In a second condition, they said, “They’re 300 pennies … that’s $3. It’s a bargain.” The unusual “pennies” phrasing distracts people. The distraction increased compliance: About one-third of the people purchased cards after hearing that they were $3, but two-thirds bought them after hearing that they cost 300 pennies.

Compliance research has significant real-world implications. Findings reveal that people can be affected by compliance techniques without being fully aware of what happened to them. Outside the lab, these techniques can become “weapons of influence” (Cialdini, 2009)—forces that cause people to comply unwittingly with requests from advertisers, political parties, and others who wish to change public opinion and behavior.

OBEDIENCE. Research on conformity and compliance shows that ordinary people who hold no position of power can influence our behavior. What about people who are in positions of power? Their influence is explored in social psychological research on obedience, which occurs when people adhere to the instructions and commands of an authority figure.

Historically, social psychologists were motivated to study obedience by events of the past century. The twentieth century witnessed extraordinarily horrific genocides, such as the deaths of 800,000 Tutsis in Rwanda (1994), 1.5 million Armenians in Turkey (1915–1918), 2 million Cambodians (1975–1979), and 6 million Jews in the Nazi Holocaust of World War II (1938–1945). It was, as one of the century’s leading historians put it, an “age of extremes” (Hobsbawm, 1994).

No one person can individually kill hundreds of thousands of others. For a genocidal system to work, a large number of people must participate. How are we to understand the actions of the thousands of people who played some role in these twentieth-century genocides? Were they all crazed maniacs—Le Bon’s “primitive beings”?

For the most part, no, these people weren’t crazed maniacs. Many would have described themselves as ordinary employees who were merely following the orders of their superiors. Consider one of the twentieth century’s most unforgettable images—“unforgettable” because it was so mundane. When Nazi officers who ran the genocidal system that put 6 million Jews to death were brought to trial after World War II, what did the world see? The officials often looked more like pencil-pushing middle managers running a bureaucracy than mass murderers running a massacre. Adolph Eichmann, who administered the transportation system that took Jews to Nazi death camps, didn’t declare his hatred for Jews when he appeared in court. He told the world that he was just following orders: “[I] had no choice but to obey the orders of the Reich government” (Von Lang & Sibyll, 1983, p. 30).

The social psychologist Stanley Milgram observed these trials and posed a scientific question: Why are some orders from authority figures so powerful that people will obey them even if it means harming or killing other human beings? He then devised experimental procedures to identify social determinants of obedience to authority. They proved to be the most compelling studies in the history of psychological science.

Before learning about the experimental procedures, first take note of Milgram’s question. He did not ask about the type of person who obeys orders. He asked about the orders themselves and the situation in which those orders are issued. Once again, then, we see a social psychologist reasoning that some social factors are so powerful that they can affect anyone.

Milgram’s experiment included three people: an experimenter, a research participant who was assigned the role of “teacher,” and a confederate who played the role of “learner” and acted according to a fixed script. In the study, the learner attempted to memorize a series of words. Whenever he made a mistake, the teacher (the real research participant) was instructed to punish him by delivering an electric shock, using the machine pictured here. As the learner made more and more mistakes (according to the script), the experimenter ordered the research participant to deliver stronger and stronger shocks. The dependent variable was the harshest punishment—that is, the highest level of shock—the teacher would deliver before refusing to go on with the experiment. (The machine did not actually deliver electric shocks to the confederate, but research participants did not know this.)

Milgram added three features to the experiment that were so extreme that one would probably expect everyone to refuse to follow the experimenter’s orders:

Participants faced incredible stress. They had agreed to be in the experiment, and the authority figure running it was ordering them to go on. Yet a person was screaming in pain and demanding to be released from the study. Who would continue to deliver shocks to the learner in a circumstance like this?

It turns out that most people would. In Milgram’s study, 26 of 40 participants—about two-thirds—obeyed the authority figure’s orders and continued delivering shocks, despite the learner’s protests, all the way up to 450 volts, the highest shock level!

Why? Did those participants not care about the learner? That’s not it. They cared a lot and, as a result, were under severe strain. “Tension,” Milgram reports, “reached extremes. … [S]ubjects were observed to sweat, tremble, stutter, bite their lips, groan, and dig their fingernails into their flesh” (1963/1971, p. 536). Yet the majority followed orders. Situational forces caused people—ordinary people who cared very much about the welfare of the learner—to deliver severe shocks.

Milgram’s results have profound implications. They show that people will obey authorities even when ordered to harm others, and even when the authority figure is merely an experimental psychologist. Real authority figures—police, government officials, military officers—have greater power to induce obedience. No wonder, then, that governments were able to order the violent campaigns that marked twentieth-century history.

“Maybe,” the optimists among you may be thinking, “this sort of brutality can only happen when someone is issuing direct orders. Otherwise, people would treat each other with kindness and respect.” Unfortunately, this sunny view of human nature is darkened by the social psychological research you’ll read about next.

“All the world’s a stage,” Shakespeare wrote. Of all the metaphors to describe human social life—“It’s a rat race,” “It’s a jungle out there”—none is more apt than Shakespeare’s. The stage has actors, the actors have roles, and the roles shape the actors’ behavior. When you’re assigned a role in a play, you know what you are expected to do. If your role is that of a hero, you shouldn’t look scared when the villains arrive. If you’re the evil stepmother, it’s a license for cruelty.

Everyday life resembles a play or movie (Scheibe, 2000). People have roles. A role is a set of behaviors that is expected of a person in a given situation. Here’s a simple example. When your psychology class meets, one person has the role of course instructor. Everyone expects a certain type of behavior from the person in that role: showing up on time for class, organizing class plans, doing a lot of talking once class begins. Maybe outside of class your professor is chronically late, disorganized, and quiet. But in class, in the role of course instructor, he or she likely is punctual, organized, and talkative.

ROLES AND THE STANFORD PRISON EXPERIMENT. How can one study the impact of roles experimentally? In everyday life, people differ not only in their roles in society, but in their personalities, intelligence, physical appearance, and many other qualities—and these factors are jumbled together. Suppose a sports coach is competitive and strong-willed. Did the role of coach create that behavior, or was it her natural personality? To study the causal impact of roles, you could create an “experimental society” in which people are assigned to roles randomly. Thanks to random assignment, if people with different roles behaved differently, you’d know the cause was the roles, not the people’s personalities.

Stanford University psychologist Philip Zimbardo and his colleagues created such a society. It was a simulated prison. In the Stanford Prison Experiment (Haney, Banks, & Zimbardo, 1973; Zimbardo, 2007), 24 college students participated in what was planned as a two-week-long study of simulated prison life. Students were randomly assigned to the role of guard or prisoner. Guards wore khaki uniforms and sunglasses, carried nightsticks, and were assigned to 8-hour work shifts. Prisoners wore loose-fitting smocks (with no undergarments) with an ID number printed on the front and back, a nylon cap on their heads, and a chain around one of their ankles. They spent 24 hours a day in the simulated prison, in the basement of the Stanford University psychology department.

Zimbardo, the “Superintendent” of the prison, gave students little explicit information about their roles. He merely told the guards to maintain order and told the prisoners that, in the simulated jail, they were to be prisoners. Unlike the Milgram experiment, there were no specific orders about exactly how to act. In principle, prisoners and guards could have behaved however they liked; they could have spent the week just relaxing.

But that’s not what they did. Instead, students assigned to the role of guard treated prisoners in a “negative, hostile, affrontive, and dehumanizing” manner (Haney et al., 1973, p. 80). They belittled the prisoners. “I got tired of seeing prisoners in their rags and smelling the strong odors of their bodies” (p. 88), a guard reported. They abused prisoners physically. “I went to cell 2 to mess up a bed which the prisoner had made,” another guard reported, “and he grabbed me, screaming that he had just made it, and … I lashed out with my stick and hit him in the chin” (p. 88).

Students assigned to the role of prisoner behaved passively, seemingly accepting that the guards were in control. They experienced great stress from the guards’ abuse, with five prisoners having to be released from the experiment due to depression, anxiety, or bouts of crying. Prisoners reported personality changes. “I began to feel,” one said, “[that] I was losing my identity, that … the person who volunteered to get me into this prison [in other words, the person’s pre-prison self] was distant from me. … I was [prisoner number] 416, I was really my number and 416 was going to have to decide what to do” (Haney et al., 1973, p. 87).

Eventually, the experiment spiraled out of control. Some prisoners staged a rebellion. Guards suppressed it forcefully. Afterward, guards treated prisoners even more harshly, compelling them to perform demeaning tasks, such as cleaning toilet bowls. Prisoners showed more and more signs of emotional disturbance. Finally, Zimbardo had to halt the experiment—after only 6 of the planned 14 days.

Why were the guards abusive and the prisoners passive? It can’t be due to their personalities, since people were assigned to their roles randomly; with a different flip of a coin, the guards would have been the prisoners and vice versa. Their differences in behavior, then, were caused by their different social roles. Once assigned to their roles, guards and prisoners knew how to act. From stories, movies, news reports, TV shows, and so forth, they understood the expected behavior of a guard and a prisoner, and their actions fit those expectations.

Zimbardo (2007) argues that the Stanford Prison experiment’s lessons extend to real-world events. For American citizens, one of the most shocking events of recent history was the abuse of prisoners by U.S. soldiers during the Iraq War. News reports and photographic evidence revealed that soldiers at the Abu Ghraib prison, near Baghdad, Iraq, had beaten prisoners, stripped them and made them assume humiliating poses, and intimidated them with military work dogs (Hersh, 2004). Were the American soldiers inherently evil people? Zimbardo argues they were not. The source of evil was not the personality of the soldiers but the situation they were in, which caused people—even people who were not inherently evil—to mistreat prisoners. “The Pentagon blamed the whole thing on a ‘few bad apples,’” Zimbardo noted, but “I knew from our experiment, if you put good apples into a bad situation, you’ll get bad apples” (Dreifus, 2007, April 3).

The Stanford Prison experiment has limitations. As the researchers themselves were aware (Haney et al., 1973), it was not a carefully designed study with multiple experimental and control conditions (see Chapter 2). It was merely a demonstration of the power of social factors over the behavior of individuals assigned to different roles. Zimbardo’s presence within the prison (as Superintendent) complicates interpretations of these factors. His behavior may have influenced participants in a manner that went beyond the effects of their assigned roles, per se (Griggs, 2014; Haslam & Reicher, 2003). Yet, even if so, the Stanford Prison experiment stands as a compelling demonstration of one of the major lessons of social psychology: the potential power of social forces over the behavior of ordinary people.

GROUP IDENTITY AND ROBBERS CAVE. Prisons are unusual—virtually the only place where one group has complete control over another. Do groups exert much influence in typical, everyday situations?

Anecdotal evidence suggests that they do. Whatever group you are a part of—a group of friends, a neighborhood, a church, an ethnic group, a city, a nation—if it is important to you, not only do you become part of the group, the group also becomes a part of you. Social psychologist Marilyn Brewer (1991, p. 467) explains that people develop social identities—an understanding of who they are in the social world—that is based significantly on their group membership. Once you identify with a group, your social identity influences your thoughts, feelings, and behavior.

Social identities are apparent in how people describe themselves. Self-descriptions commonly include not only a personal identity (e.g., physical characteristics, personality traits) but also a social identity; people say that they see themselves as members of groups (Hornsey, 2008).

Group identities can form rapidly. Even people who have been members of groups for only a few days may strongly identify with their group and see others as rivals. A classic study by Muzafer Sherif and collaborators (1954), conducted at Robbers Cave State Park in Oklahoma, illustrates this. Sherif divided 22 fifth-grade boys at a summer camp into two random, equally sized groups. The groups spent time apart during the camp’s first week. In that week, boys quickly became attached to their group, even giving their group a nickname: the “Rattlers” and the “Eagles.” When the boys were then brought together for sports competitions, they were heated rivals. They called each other names, burned each other’s group flag, and planned raids of the others’ campsite. They looked like lifelong enemies—even though the groups were formed randomly just a week earlier!

Sherif was able to eliminate the group rivalry as quickly as he created it. In the last week of camp, he presented challenges that could only be accomplished if the two groups worked together: He disrupted the camp water supply (which required the two groups to work together on repairs), told the boys that the camp couldn’t afford to rent a movie (which prompted the Rattlers and Eagles to pitch in money together), and caused a truck to become stuck in mud (with the boys literally pulling together to get it out). Working together toward shared goals transformed the groups. Former enemies became friends; they sang songs together and laughed about their earlier rivalry. By the time camp ended, the Eagles and Rattlers wanted to leave camp together, on one bus, and cheered when staff said they could.

Sherif’s results have fascinating implications. They suggest that group rivalries can be reduced by having rivals work together toward a shared goal. History shows that shared goals foster a sense of unity. For example, the 9/11 tragedy enhanced American’s sense of national unity, as people realized that they needed to work cooperatively, as one big group, to achieve their aim of national security (Li & Brewer, 2004).

ROLE AMBIGUITY AND BYSTANDER INTERVENTION. The studies you’ve read about so far have something in common: Participants know their role. They are teachers or learners, prisoners or guards, Rattlers or Eagles. But sometimes we don’t know what our role is. If a friend is drinking heavily at a party, what is your role—to be the voice of reason who tells him to stop drinking or the party buddy who encourages more fun? If two friends are arguing, what is your role—to act as the moderator who tries to resolve their differences or the passive onlooker who gets out of their way? And what, the social psychologist asks, determines the role you choose?

Research exploring this question was sparked by a tragedy in 1964. New York City resident Kitty Genovese was stabbed to death while returning home from work. Thirty-eight local residents heard her screams. Some looked out their apartment windows and witnessed the violence. But during the long and bloody attack, none intervened. It wasn’t until the attack was long over that anyone even called the police.

Why did people just stand by instead of trying to help? Research on bystander intervention by John Darley and Bibb Latané (1968) suggests an answer. Darley and Latané invited participants to a discussion of issues in college life. The discussion took place through an intercom system; each participant could hear, but not see, the other participants, who were in nearby rooms. In reality, only one discussant was a real research participant; the others were confederates. During the discussion, the experimenters staged an emergency in which one of the confederates appeared to be having a seizure. “I’m-er-er-h-h-having a-a-a real problem,” said a voice on the intercom, “gonna die-er-help-er-er-seizure-er-.” The dependent variable was the time that elapsed before the real research participant took action to help the apparent seizure victim. The independent variable was group size. Based on the number of voices heard over the intercom, the real participant thought the group consisted of either two, three, or six people.

Group size strongly influenced helping behavior (Figure 12.2). In bigger groups, there was a bystander effect: People were slower to intervene, and in many cases never intervened at all, when a lot of other bystanders were around. Half the participants assigned to six-person groups took nearly two minutes to respond. By comparison, in the two-person groups, when participants believed they were the only bystander who could help, almost everyone responded in less than a minute.

Why was group size so important? In emergencies, bystanders are aware of the people involved in the emergency and also the other bystanders in the vicinity. When there are no other bystanders, an individual knows that he or she is the only person who can provide help. But when lots of bystanders are around, one of them might provide assistance. The presence of other bystanders creates a diffusion of responsibility: lowered feelings of personal obligation to respond to someone in need, because others may respond. Larger groups diffuse responsibility and thereby lower people’s tendency to intervene.

Darley and Latané’s findings teach an important lesson. When hearing that city dwellers failed to respond to an emergency, one might conclude that city dwellers are callous and uncaring. But research indicates that the explanation is the situation, not the people. In big cities, there are likely to be more bystanders, more diffusion of responsibility, and thus less helping. No matter who you are, diffused responsibility causes you to be less likely to help.

Crowds and groups can affect your behavior. But the encounters that most affect your life as a whole are close relationships—those that involve frequent contact and strong psychological connections with another person (Kelley et al., 1983).

Some close relationships occur naturally. From birth, we are in the hands of parents and other caregivers, with whom our first close relationships are formed. Later in life, however, we have choices. We make friends with people we like, develop romantic relationships with people to whom we are attracted, and form committed relationships with people we love. Let’s look at the social psychology of liking and friendships, attraction and romantic relationships, and love and commitment.

LIKING AND FRIENDSHIPS. Look at Figure 12.3, a diagram of an apartment building. Which people, from which of the 10 apartments, do you think are most likely to be friends?

The question might sound ridiculous. How can you predict who will be friends before you know more about the individual people—which ones like loud parties or quiet teas, Mozart or hip-hop, cats or dogs?

As it turns out, you can predict quite well. The big predictor, a team of social psychologists found, is physical distance (Festinger, Schachter, & Back, 1950). The people in the apartment complex shown in Figure 12.3 who tended to like each other and be friends were those who lived near each other; the building’s most common friendship pattern, by far, was that people were friends with their next-door neighbors. Across different floors of the building, the placement of stairwells influenced friendship patterns. People who were closely connected by a stairwell (e.g., people in apartments 7 and 1) were more likely to be friends than others (e.g., people in apartments 7 and 3).

A study of trainees at a police academy produced a similar result (Segal, 1974). The academy assigned seats in classrooms alphabetically, by last name. After their academy training, officers named their closest friends in the police force. Nearly half the time, they named people right next to them in the alphabet—the people who were closest to them physically in the classroom (Segal, 1974).

Why would physical distance have such a big effect? One explanation is mere exposure; people tend to like things more after they encounter them frequently (see the section on mere exposure and attitude change later in this chapter). We see the folks next door more frequently than the folks far away, and so we like them.

Proximity is not the only factor that affects liking, however. People also tend to like friends who support their opinions, help them to take part in activities they enjoy, and make them feel better about themselves (Finkel & Eastwick, in press). But one factor that reliably causes people to like each other is living next door.

ATTRACTION AND ROMANTIC RELATIONSHIPS. Some close relationships are just friendships. But others have that special spark: romance. What causes us to be romantically attracted to some people but not others?

To find out, social psychologists threw a party—that, in reality, was a psychology experiment (Walster et al., 1966). At the start of an academic year, they invited more than 700 university freshman to a dance party. Three aspects of the party made it a research study: Before the party, (1) students reported their psychological qualities (social attitudes, personality styles, intelligence) to researchers, and (2) the researchers assigned students to dates for the party randomly (each received a randomly chosen opposite-sex partner). After the party, (3) students indicated whether they liked their date and wanted to see that person again. The researchers then determined which psychological characteristics predicted romantic attraction.

Which psychological quality do you think predicted attraction? As it turns out, none were strong predictors. But something else was: physical attractiveness. Unknown to students, as each entered the party, researchers rated their level of physical attractiveness. Physical attractiveness strongly predicted romantic attraction; if a dating partner was rated as highly physically attractive, students wanted to see that person again—no matter what their psychological qualities. Among both men and women, “the only important determinant” of desire for another date “was the date’s physical attractiveness” (Walster et al., 1966, p. 508).

The party study shows what happens when people are paired randomly. But what happens when people have a choice? How do they select others to date? Most can tell, intuitively, that things might not work out if they pursue the singularly most attractive and popular person in town. People therefore tend to “match,” that is, to pursue dating partners whose level of physical attractiveness and popularity is similar to their own (Taylor et al., 2011). In the game of dating, people are strategic.

LOVE AND COMMITMENT. Sometimes the spark of romance triggers the enduring flame of love. Social psychology cannot unravel all the mysteries of love, but it can answer some questions. One asks: What is it—what psychological ingredients have to be present for you to say that you are “in love”?

To find out, psychologists asked a large group of people to rate whether each of a large number of psychological experiences is a component of love (Aron & Westbay, 1996). Statistical analyses of their ratings identified three main components of love: (1) euphoric and sexually aroused feelings of passion; (2) honest and supportive intimacy; and (3) loyal, devoted commitment (Table 12.1). Love, then, is more than romantic attraction; it includes deep commitment within a relationship that is open and supportive.

The relationships that we call “love” have three features: passion, intimacy, and commitment (Aron & Westbay, 1996). The table lists the psychological experiences that people most strongly associate with each.

12.1

Can all three components of love last a lifetime? You may worry that passion is a flame that inevitably flickers out, even if intimacy and commitment remain. If so, then scientific evidence can calm your worry. Research shows that, for some lucky couples, the flames of passion burn for a lifetime. Both qualitative and quantitative evidence support this conclusion (Acevedo & Aron, 2009). When married couples are interviewed, qualitative analyses reveal substantial subgroups of couples who say that they are intensely, romantically in love, even after decades of marriage. When feelings are measured quantitatively, many long-term-married couples are found to have levels of passion that match those of newlyweds.

These happy marriages have major benefits. People in romantically successful marriages are happier with their life as a whole, enjoy better mental health, and even experience better physical health (Acevedo & Aron, 2009).

That last result might sound mysterious: Why would love cause people to feel better physically? Research has begun to unravel that mystery. In one study, participants were asked to rate the amount of pain they experienced when exposed to a very hot physical stimulus (Younger et al., 2010). While this was happening, the participants looked at pictures showing either (1) their romantic partner or (2) an equally attractive acquaintance. When viewing their romantic partner, participants were in less pain. Brain images taken during the study showed why. Pictures of the romantic partner activated the brain’s reward centers (i.e., neural systems involved in the processing of positive, rewarding stimuli). Activation of reward centers, in turn, directly reduces the experience of pain. Romantic love thus was like a pain-relieving drug; it activates biological mechanisms that reduce pain.