Informed decisions

Diverse juries make better decisions, research shows

“Race makes people see the same thing very differently,” social psychologist Samuel Sommers says. For instance, he says, consider the reaction to the O.J. Simpson trial. Remember the TV images of African-Americans cheering the verdict, while whites appeared dismayed?

Samuel Sommers © ZARA TZANEV

“It’s an overused example,” Sommers acknowledges. “But it’s a good example of how [people of different races] can see the same phenomenon in very different ways.”

Sommers, assistant professor of psychology, researches the influence of race-related norms on perception, judgment and behavior. He has been fascinated by the interplay of psychology and the legal system ever since he took a course on the subject as an undergraduate at Williams College.

“Combining those seemed a natural fit,” he said. “What really interests me about the law is the human dynamic of what goes on in the courtroom.”

Sommers’ latest research, published in the April issue of the Journal of Personality & Social Psychology, tackles racial diversity and group decision-making—specifically, decision-making by juries.

Wiggle room
“A controversial issue in the justice system is how African-American defendants are treated by all-white juries,” Sommers said. Although the U.S. Supreme Court has ruled on several occasions that potential jurors cannot be excluded from serving based on race, “jury representation is still difficult for the courts,” Sommers said. “You often do end up with all-white juries even in racially mixed areas…the law allows for a lot of wiggle room on the issue.”

For his study, Sommers assembled six-person mock juries, with participants drawn from an actual jury pool in the midst of jury duty. Some of the panels consisted entirely of white, non-Latino jurors; others had four white jurors and two African-American jurors. For the purposes of the experiment, Asian-American and Latino jurors were not chosen. All the mock juries were shown the same video of a trial involving an African-American defendant charged with sexual assault.

“The assumption was that white jurors in diverse groups would be less likely to vote to convict a black defendant,” Sommers said. And indeed, that did prove to be the case. In addition, the decision-making behavior of the white jurors, as a group, changed when African-American jurors were present during deliberations.

“The diverse juries discussed more facts from the case during deliberations,” Sommers said. “They made fewer factual errors in discussing the case.” These differences were not simply a result of the performance of the African-American jurors; the white jurors on the diverse juries exchanged a wider range of information and were “more amenable to a discussion of racism” than those on the all-white panels.

Influencing behavior
“Diverse juries had a diversity of perspectives. They made fewer mistakes and processed the information more carefully,” Sommers said. “They had more knowledgeable and thorough discussions, and that can have a significant influence on trial outcomes.”

The effects of diversity also went beyond information exchange, Sommers said. The mere presence of non-white colleagues appeared to influence behavior. “Before the jurors started talking, we asked how they would vote. Even before deliberations, white jurors on a diverse jury were more likely to vote not to convict than those on an all-white jury,” he said.

“This raises a broader question,” Sommers said. “At a cognitive level, a homogenous group lets you be lazier, not challenged.”

The drawback to using a “mock” situation, Sommers said, is that the jurors knew there would be no repercussions from their decision. (There is no way to study the workings of actual juries as they occur because deliberations are private.) Other techniques for investigating the role of race in jury deliberations are conducting post-trial interviews, which rely on the subjective recall of individual jurors, and compiling data from archival cases, which leave many factors unaccounted for.

While this issue is of particular interest to lawyers and judges, “I hope my work is not just related to the legal system, but that it relates to groups, period,” Sommers said. His interest in psychology and social justice issues led Sommers to initiate the psychology department’s Diversity and Cognition Colloquium Series.

“Race, gender, culture, sexual orientation—how do they affect our interactions?” he asked. “These things influence our lives, whether we like to think it or not.”

Helene Ragovin is a senior writer in Tufts Office of Publications. She can be reached at