Monday, March 12, 2007
A new study authored in part by a University of California Professor Robert J. MacCoun of public policy and law throws cold water on a common theory that a confident witness who errs in trial testimony is still more credible than a less confident witness who similarly slips up.
The researchers concluded that self-assured witnesses who make a mistake - even on issues of little importance - undermine their credibility by raising doubts about their competency, their ability to judge their own abilities and their motivations.
"People giving testimony, or advice, or opinions should therefore be careful to express appropriate degrees of confidence in their assertions," the researchers write in a summary of their report in the January issue of the journal Psychological Science. "Otherwise, the 13th stroke of the clock will cast the other 12 in doubt."
The researchers included Robert J. MacCoun of UC Berkeley, a professor at the Goldman School of Public Policy and at the School of Law (Boalt Hall); Elizabeth Tenney, a doctoral student in psychology at the University of Virginia; Barbara Spellman, an associate professor of psychology at the University of Virginia; and Reid Hastie, a professor of behavioral science at the University of Chicago.
MacCoun said the team's findings challenge the frequent tendency of attorneys to pressure their witnesses to project a strong sense of confidence and to minimize the use of hedges like "I think" or "maybe." Academic experts encounter similar pressures when asked to testify before policy makers, he said. But this first-of-its-kind study shows that such a strategy can backfire if a cocky witness gets caught in a mistake. Rest of Story. . . [Mark Godsey]