Competition in the Courtroom: When Does Expert Testimony Improve Jurors' Decisions?

Many scholars lament the increasing complexity of jury trials and question whether the testimony of competing experts helps unsophisticated jurors to make informed decisions. In this paper, we analyze experimentally the effects that the testimony of competing experts has on 1) sophisticated versus unsophisticated subjects' decisions and 2) subjects' decisions on difficult versus easy problems. Our results demonstrate that competing expert testimony, by itself, does not help unsophisticated subjects to behave as though they are sophisticated, nor does it help subjects make comparable decisions on difficult and easy problems. When we impose additional institutions (such as penalties for lying or a threat of verification) upon the competing experts, we observe such dramatic improvements in unsophisticated subjects' decisions that the gap between their decisions and those of sophisticated subjects closes. We find similar results when the competing experts exchange reasons for why their statements may be correct. However, these additional institutions and the experts' exchange of reasons are much less effective at closing the gap between subjects' decisions on difficult versus easy problems.