In chapter 2, when I was discussing what made someone like Mark Alpert so important in word-of-mouth epidemics, I talked about two seemingly counterintuitive aspects of persuasion. One was the study that showed how people who watched Peter Jennings on ABC were more likely to vote Republican than people who watched either Tom Brokaw or Dan Rather because, in some unconscious way, Jennings was able to signal his affection for Republican candidates. The second study showed how people who were charismatic could — without saying anything and with the briefest of exposures — infect others with their emotions. The implications of those two studies go to the heart of the Law of the Few, because they suggest that what we think of as inner states — preferences and emotions — are actually powerfully and imperceptibly influenced by seemingly inconsequential personal influences, by a newscaster we watch for a few minutes a day or by someone we sit next to, in silence, in a two-minute experiment. The essence of the Power of Context is that the same thing is true for certain kinds of environments — that in ways that we don't necessarily appreciate, our inner states are the result of our outer circumstances. The field of psychology is rich with experiments that demonstrate this fact. Let me give you just a few examples.

In the early 1970s, a group of social scientists at Stanford University, led by Philip Zimbardo, decided to create a mock prison in the basement of the university's psychology building. They took a thirty-five-foot section of corridor and created a cell block with a prefabricated wall. Three small, six- by nine-foot cells were created from laboratory rooms and given steel-barred, black-painted doors. A closet was turned into a solitary confinement cell. The group then advertised in the local papers for volunteers, men who would agree to participate in the experiment. Seventy-five people applied, and from those Zimbardo and his colleagues picked the 21 who appeared the most normal and healthy on psychological tests. Half of the group were chosen, at random, to be guards, and were given uniforms and dark glasses and told that their responsibility was to keep order in the prison. The other half were told that they were to be prisoners. Zimbardo got the Palo Alto Police Department to "arrest" the prisoners in their homes, cuff them, bring them to the station house, charge them with a fictitious crime, fingerprint them, then blindfold them and bring them to the prison in the Psychology Department basement. Then they were stripped and given a prison uniform to wear, with a number on the front and back that was to serve as their only means of identification for the duration of their incarceration.

The purpose of the experiment was to try to find out why prisons are such nasty places. Was it because prisons are full of nasty people, or was it because prisons are such nasty environments that they make people nasty? In the answer to that question is obviously the answer to the question posed by Bernie Goetz and the subway cleanup, which is how much influence does immediate environment have on the way people behave? What Zimbardo found out shocked him. The guards, some of whom had previously identified themselves as pacifists, fell quickly into the role of hard-bitten disciplinarians. The first night they woke up the prisoners at two in the morning and made them do pushups, line up against the wall, and perform other arbitrary tasks. On the morning of the second day, the prisoners rebelled. They ripped off their numbers and barricaded themselves in their cells. The guards responded by stripping them, spraying them with fire extinguishers, and throwing the leader of the rebellion into solitary confinement. "There were times when we were pretty abusive, getting right in their faces and yelling at them," one guard remembers. "It was part of the whole atmosphere of terror." As the experiment progressed, the guards got systematically cruder and more sadistic. "What we were unprepared for was the intensity of the change and the speed at which it happened," Zimbardo says. The guards were making the prisoners say to one another they loved each other, and making them march down the hallway, in handcuffs, with paper bags over their heads. "It was completely the opposite from the way I conduct myself now," another guard remembers. "I think I was positively creative in terms of my mental cruelty.'' After 36 hours, one prisoner began to get hysterical, and had to be released. Four more then had to be released because of "extreme emotional depression, crying, rage, and acute anxiety." Zimbardo had originally intended to have the experiment run for two weeks. He called it off after six days. "I realize now," one prisoner said after the experiment was over, "that no matter how together I thought I was inside my head, my prisoner behavior was often less under my control than I realized." Another said: "I began to feel that I was losing my identity, that the person I call ___, the person who volunteered to get me into this prison (because it was a prison to me, it still is a prison to me, I don't regard it as an experiment or a simulation…) was distant from me, was remote, until finally I wasn't that person. I was 416. I was really my number and 416 were really going to have to decide what to do."

Zimbardo's conclusion was that there are specific situations so powerful that they can overwhelm our inherent predispositions. The key word here is situation. Zimbardo isn't talking about environment, about the major external influences on all of our lives. He's not denying that how we are raised by our parents affects who we are, or that the kind of schools we went to, the friends we have, or the neighborhoods we live in affect our behavior. All of these things are undoubtedly important. Nor is he denying that our genes play a role in determining who we are. Most psychologists believe that nature — genetics — accounts for about half of the reason why we tend to act the way we do. His point is simply that there are certain times and places and conditions when much of that can be swept away, that there are instances where you can take normal people from good schools and happy families and good neighborhoods and powerfully affect their behavior merely by changing the immediate details of their situation.

This same argument was made, perhaps more explicitly, in the 1920s in a landmark set of experiments by two New York-based researchers, Hugh Hartshorne and M.A. May. Hartshorne and May took as their subjects about eleven thousand schoolchildren between the ages of eight and sixteen, and over the course of several months they gave them literally dozens of tests, all designed to measure honesty. The types of tests that Hartshorne and May used are quite central to their conclusion, so I'll identify a number of them in some detail.

One set, for example, was simple aptitude tests developed by the Institute for Educational Research, a precursor to the group that now develops the SATs. In the sentence-completion test, children were asked to fill in words that had been left blank. For example: "The poor little ___ has nothing to ___; he is hungry." In the arithmetic test, children were given math questions like "When sugar costs 10 cents a pound, how much will five pounds cost" and asked to write their answers in the margin. The tests were given in only a fraction of the time usually needed for completion, so most children had lots of unanswered questions, and when the time was up the tests were collected and graded. The following day the students were given the same kinds of tests again, with questions that were different but of equal difficulty. This time, though, the students were given an answer key and, under minimal supervision, told to grade their own papers. Hartshorne and May, in other words, had set up a sting operation. With the answers in hand and lots of unanswered questions, the students had ample opportunity to cheat. And with the previous day's tests in hand. Hartshorne and May could compare the first day's answers to the second, and get a good sense of how much each student was cheating.