Why does a jury have to be a group of six or twelve instead of say, one person? Because groups make better decisions than individuals, most people would say.
And they do make better decisions -- sometimes. Except when they don't:
Much of the time, both private and public groups often blunder not in spite of deliberation but because of it. After deliberation, companies, labor unions, and religious organizations often make bad decisions; the same point holds for governments.
That's Profs. Cass Sunstein and Reid Hastie talking, the University of Chicago's law school and business school respectively. Their paper "Four Failures of Deliberating Groups" has just been posted on SSRN. Jury fans need to understand this paper, and jury doubters will love it.
"The truth played a role, too . . ."
Drawing on research from psychology and business as well as a few studies of jurors, Sunstein and Hastie patiently list the ways groups can go wrong. Mistakes begin at the simplest level, when an individual who has the facts right cannot convince a mistaken majority:
[A] comprehensive study has demonstrated that majority pressures can be powerful even for factual questions to which some people know the right answer. The study involved twelve hundred people, forming groups of six, five, and four members. Individuals were asked true-false questions involving art, poetry, public opinion, geography, economics, and politics. They were then asked to assemble into groups, which discussed the questions and produced answers. The majority played a substantial role in determining each group’s answers. The truth played a role, too, but a lesser one. If a majority of individuals in the group gave the right answer, the group’s decision moved toward the majority in 79 percent of the cases. If a majority of individuals in the group gave the wrong answer, the group’s decision nonetheless moved toward the majority in 56 percent of the cases.
"Much garbage out"
And it gets worse. Groups can not only pick up the errors of individual members, but they can make them bigger:
For purposes of assessing deliberation, a central question is whether groups avoid the errors of the individuals who comprise them. There is no clear evidence that they do, and often they do not—a vivid illustration of the principle, “garbage in, garbage out,” in a way that mocks the aspiration to collective correction of individual blunders. In fact, individual errors are not merely replicated but actually amplified in group decisions—a process of “some garbage in, much garbage out.”
These aren't tort reformers gathering research to support a cause, or at least I don't think so. The paper hardly mentions juries, focusing more on decisionmaking in the business world -- and Sunstein clerked for Thurgood Marshall and is campaigning for Barack Obama. The fact is, they're right that these errors can and do happen. Watch a few mock trials and you'll quickly observe the "four failures" Sunstein and Hastie describe: "amplification of cognitive errors," "cascades," "group polarization," and "over-weighting common knowledge."
If you value juries, and most people do, the value of this paper is the way it dramatizes a skill that all lawyers need and most don't have. You need to be able to explain how juries can make good decisions: how to disagree with respect, how to catch each other's errors, and so on. It isn't easy, but Sunstein and Hastie will soon offer help; this paper is a chapter from their upcoming book, called Smart Groups.
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Note: Thanks to The Situationist for flagging this paper. The Situationist is relevant to jury watchers even when (maybe especially when) its topic is far from the courtroom; if you ever decide to reduce the number of blogs you read, you should probably drop mine before you drop theirs.
(Photo by Julie Berlin at http://www.flickr.com/photos/jule_berlin/839245545/; license details there.)
