Deliberating groups, including juries, typically end up in a more extreme position in line with their predeliberation tendencies. A jury whose members are inclined, before deliberation, to find a defendant not guilty will likely render a verdict of not guilty; a jury whose members want to award punitive damages will likely produce an award higher than that of the median juror. The phenomenon of group polarization, found in many domains, stems from a combination of information pooling and peer pressure. The events portrayed in the film 12 Angry Men seem to defy the logic of group polarization, but the film nonetheless shows an acute psychological sense.

One of the most striking features of the film 12 Angry Men is its apparent inconsistency with what social scientists know about group dynamics. True, Henry Fonda is an impressive guy, in this movie as in every other. But a single juror is highly unlikely to be able to move eleven people who are leaning the other way. In fact, the usual pattern is just the opposite: If almost all members of a twelve‐member jury are inclined to convict the defendant, the jury is overwhelmingly likely to convict that defendant. My goal here is to examine why this is so — and to connect that examination with an inquiry into the social dynamics of the jury in 12 Angry Men. It turns out that the movie is not quite as unrealistic as it seems (Brown 1985). To appreciate that conclusion, let us begin with some political issues.

In the summer of 2005, my colleagues and I conducted a small experiment in democracy in Colorado (Hastie, Schkade, and Sunstein Forthcoming). About sixty American citizens were brought together and assembled into ten “juries,” mostly consisting of six people. Members of each “jury” were asked to deliberate on three of the most controversial issues of the day:

  • Should states allow same‐sex couples to enter into civil unions?

  • Should employers engage in “affirmative action” by giving a preference to members of traditionally disadvantaged groups?

  • Should the United States sign an international treaty to combat global warming?

As the experiment was designed, the groups consisted of “liberals” from Boulder and “conservatives” from Colorado Springs. In election‐year parlance, they comprised five “Blue State” groups, whose members initially tended toward liberal positions in general, and five “Red State” groups, whose members tended generally toward conservative positions. People were asked to state their opinions anonymously both before and after fifteen minutes of group discussion.

What was the effect of discussion? In almost every jury, people were moved toward a more extreme position in line with the original tendency within the group. “Outliers”— those whose opinions, like Juror 8 portrayed by Henry Fonda in 12 Angry Men, diverged significantly from the majority — were never to able to make much progress; they were more likely to become converts than converters. More specifically, discussion made civil unions even more popular among liberals and even less popular among conservatives. Liberals favored an international treaty to control global warming before discussion; they favored it more strongly after discussion. Conservatives were slightly negative about that treaty before discussion; they strongly opposed it after discussion. Mildly favorable toward affirmative action before discussion, liberals became strongly favorable toward affirmative action after discussion. Firmly negative about affirmative action before discussion, conservatives became even more negative about affirmative action after discussion.

The Colorado experiment is an illustration of the well‐established phenomenon of group polarization, by which members of deliberating groups typically end up in a more extreme position in line with their tendencies before deliberation began (Brown 1985). Within small groups, those with unusual or contrary positions are rarely able to move other group members in their preferred direction. In fact, group polarization has been found in hundreds of studies involving people in more than a dozen countries (Brown 1985). In one study, white people who were not inclined to show racial prejudice showed less prejudice after deliberation than before; but white people who were inclined to show such prejudice displayed even more prejudice after deliberation (Myers and Bishop 1970). Similarly, after deliberation, French people became more distrustful of the United States and its intentions with respect to foreign aid (Brown 1985). In the same vein, feminism became more attractive to women after internal discussions, at least if those women were antecedently inclined to favor feminism (Myers 1975).

In the domain of law, as well, ample evidence attests to the pervasiveness of group polarization. Group polarization can occur for judgments of guilt and for sentencing in criminal cases (Myers and Kaplan 1976). Studies have shown that when a strong majority of jurors are inclined to convict, the jury is likely to convict. Across the general run of cases, there is essentially zero probability that a group of eleven to one will shift to zero to twelve (Brown 1985) — which makes accepting the verisimilitude of the events depicted in 12 Angry Men somewhat problematic.

In punitive damage cases as well, deliberating juries have been found to polarize, producing awards that are often higher than those of the median juror before deliberation begins (Schkade, Sunstein, and Kahneman 2000). When individual jurors begin with a high degree of moral outrage about a defendant's conduct, juries become more outraged after deliberation than their median member had been before deliberation; dollar awards are often as high as or even higher than the highest award favored, before deliberation, by any individual juror. For example, Schkade, Sunstein, and Kahneman (2000) found in 27 percent of the cases they studied that the jury's award was as high as or higher than that favored by any individual juror before deliberation.

Why does group polarization occur? There are several explanations (see Brown 1985).The first and most important involves the exchange of information. Fortunately, most people do listen to the arguments made by other people. In any group whose members have a definite initial inclination, the views of most people in the group will (by definition) be skewed in the direction of that inclination. Suppose that the majority position within a group is that a defendant should be convicted, that global warming is a serious problem, or that the incumbent president is doing a terrific job. As a statistical matter, the arguments favoring that initial position will be more numerous than the arguments pointing in the other direction. Individuals will have heard of some, but not all, of the arguments that emerge from group deliberation. As a result of hearing the various arguments, deliberation will lead people toward a more extreme point in line with what group members initially believed. Through this process, many minds can polarize, and in exactly the same direction.

The second explanation involves social comparison. People usually want to be perceived favorably by other group members, even on a jury. Sometimes people's publicly stated views are, to a greater or lesser extent, a function of how they want to present themselves and to be perceived. Once they hear what others believe, some will adjust their positions at least slightly in the direction of the dominant position. In a left‐wing group, for example, those who lean to the left will be more acceptable, and for this reason they might well end up leaning somewhat more to the left. So too on a jury: most people do not want to be perceived as silly or stupid, so if eleven people are inclined to convict a defendant, the twelfth will usually go along.

The third explanation of group polarization stresses the close links among confidence, extremism, and corroboration by others (Baron et al. 1996). As people gain confidence, they usually become more extreme in their beliefs. Agreement from others tends to increase confidence, and for this reason like‐minded people, having deliberated with one another, become more extreme as they become less tentative. In many contexts, people's opinions become more extreme simply because their views have been corroborated, and because they become more confident after learning that others share their views (Baron et al. 1996). So, too, on a criminal jury: if ten people want to convict a defendant, and two others are unsure, their proconviction inclinations will be strengthened after corrobation. If the two others are Juror 8, they must have a lot of confidence to resist the impact of the other jurors' views.

For juries, the central lesson is clear. If most jury members believe that a defendant is guilty, the jury is likely to convict that defendant, simply because it will polarize in the direction of a guilty verdict. The principal qualification involves the “beyond a reasonable doubt” standard; that standard creates a deliberate skew in the defendant's favor, and that skew will also affect the jury (MacCoun and Kerr 1988). But the skew is most unlikely to save the defendant if only one or two jurors believe that he or she is innocent.

At this point, one might easily conclude that 12 Angry Men is a bit of a fairy tale — gripping to watch, and entertaining too, but psychologically implausible. On the other hand, simple intuition and casual empiricism suggest that it is possible for one person to sway eleven others. As one example, consider the tale of the Emperor's New Clothes, in which a small boy, having said what he sees, is able to turn around a large group of people who have operated under (what they know in their hearts to be) a fiction. ButJuror 8's task is much harder. He must convince people who actually believe that the defendant is guilty.

To understand why he succeeds, and why the movie works, notice three simple points. First, the most guilt‐inclined jurors have very little information, and Juror 8 has much more, or at least he is able to ask the right questions. In most groups, the distribution of initial information strongly favors the position that most people initially hold; this is not true in the context of 12 Angry Men. Second, Juror 8 is a firm, highly likable, rational, and generally confident dissenter, relatively impervious to the ordinary kinds of social influence that dampen minority positions (Sunstein 2003). Third, the least competent jurors are the most certain that the defendant is guilty; the most competent jurors are the most ambivalent (Brown 1985). The audience can plainly see this fact and hence the stage is set for a reversal of opinion: if Juror 8 can convince the most competent jurors, who are already ambivalent, he might be able to create a cascade in the defendant's favor.

If we want to know how most groups, including most juries, tend to work, we will not take 12 Angry Men very seriously. Group polarization is the human regularity, and deliberation rarely leads group members to abandon their initial inclination. But however rare, exceptions are important and revealing. 12 Angry Men works in large part not because the outcome is realistic, but because the movie shows a realistic and even acute understanding of the kinds of processes that produce the rare exceptions.

Those rare exceptions are exceedingly important. Over the long arc of history, those with a minority position have often proved able to convince the majority; consider the movements for abolishing slavery, civil rights, women's suffrage, and environmental protection. Group polarization is the general rule, but 12 Angry Men has the signal virtue of casting a clear light on the social processes by which one or a few can indeed convince the many.

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