How good are you at staying open-minded until you've heard all the facts, or both sides of a story? If you're anything like the people that Kurt Carlson and Edward Russo from Cornell University's Johnson Graduate School of Management recently studied, then you're not very good at all. The duo wanted to find out if so-called predecisional distortionwhich is known to sway consumer and management decisionsmight also affect jurors. In other words, would tentative leanings one way or the other bias how jurors viewed new evidence? The results, published in the June issue of the Journal of Experimental Psychology: Applied, were a resounding yes.

In their first experiment, Carlson and Russo presented 126 college students with packets containing detailed information (background facts, opening arguments, witness affidavits) about a mock civil case. Another 122 students received similar information about a mock criminal case. They showed all of the subjects a 20-minute video, made for jurors in Wisconsin, asking them not to reach "hasty opinions or conclusions," and instructed both groups to read through the material, marking down as they went which evidence supported which side and which verdict they favored. The students were asked to give a decision at the end without looking back at their notes.

When the scientists analyzed the results, they found that 75 percent of the students exhibited some predecisional distortion. And when they repeated the experiment with a group of 148 prospective jurors at the Kenosha County courthouse in Wisconsin, they discovered that 85 percent of these people showed signs of predecisional distortion. What's more, the scientists note that "prospective jurors in a courthouse environment exhibited about twice the magnitude of the students' distortion." They suggest that these older adults may have held stronger beliefs in the first place.

"Much of the work on juror decision making assumes that the evidence is evaluated without bias," Carlson says, "and if that bias exists at all, it occurs in how evidence is weighed, or how the rule of law is applied by jurors. Our work illustrates a somewhat more primitive bias." In conclusion, the scientists write that "any form of overall judgment should be delayed as long as possible."