Leonard Bickman

Leonard Bickman was a social psychologist who, with Stanley Milgram and Lawrence Berkowitz, conducted a 1968 street-corner study of how people respond to others’ attention. By varying the number of men looking upward, the researchers showed how a visible crowd can become evidence in its own right: passersby may follow not because anyone pressures them, but because they infer that many people must have seen something worth looking at. The study gives Bickman a concise but important role in the book’s account of collective judgment: group influence can be sensible social learning, yet it can also undermine the independence on which sound collective decisions depend.

Identity and Research

The book identifies Bickman as one of three social psychologists responsible for the study, alongside Stanley Milgram and Lawrence Berkowitz. It does not supply a personal biography or describe his individual contribution separately from theirs. His place in the narrative is instead defined by a collaborative experiment that makes an abstract question about group influence visible on an ordinary street corner.

The Street-Corner Study

In 1968, the researchers began with a single man standing on a street corner and looking up at an empty sky for sixty seconds. Only a tiny fraction of the pedestrians stopped to see what he was watching; most continued on their way. They then increased the number of people gazing upward to five. Four times as many pedestrians stopped. With fifteen men looking up, 45 percent of passersby joined them, and when the group grew further, more than 80 percent tilted their heads toward the sky.

The changing numbers made the social influence measurable. The scene offered no visible object to explain the men’s attention: the evidence available to pedestrians was the behavior of the observers themselves. As the number of people looking upward increased, so did the proportion of passersby who copied their action. The study thus presented group influence not as an abstract disposition but as a response that intensified with each additional observer.

Social Proof and Its Limits

The book stresses that the experiment is not simply evidence of conformity. The pedestrians were not described as looking up because of peer pressure or fear of reprimand. Rather, they assumed that a growing number of people would not all be looking upward without a good reason. This is social proof: using other people’s behavior as evidence when the situation is uncertain. The inference can be reasonable; if a group often knows more than an individual, following its lead can be a sensible strategy.

But the logic contains its own danger. Each person who follows adds another apparent confirmation for the next person, even when the original signal has not been independently checked. The book’s qualification is that if too many people adopt the strategy of following the group, it ceases to be sensible and the group ceases to be smart. Bickman’s study therefore illustrates both the usefulness of social learning and the way an apparently informative crowd can magnify its influence without adding new knowledge.

Role in the Book’s Argument

The street-corner experiment appears in a discussion of whether people can make collectively intelligent decisions while continually interacting with one another. Its rising participation rates dramatize how observation can become a feedback loop: the growing crowd attracts more attention, and each new participant makes the crowd look more persuasive. That mechanism differs from a group independently combining its members’ information, because the people who join may be responding to the same visible cue rather than contributing distinct evidence.

Bickman’s documented role remains bounded to the study and its use in the book’s argument; the text gives no further account of his career or personal life. The experiment’s lasting significance within that account lies in the distinction it clarifies: people may follow others for a rational reason, yet a strategy that works when the group has independent knowledge can fail when following itself becomes the group’s main source of evidence.