The effects of confederate influence and confidence on the accuracy of crime judgements.

Building on recent work which has investigated social influences on memory and remembering, the present experiment examined the effects of social pressure and confederate confidence on the accuracy and confidence of eyewitnesses. Sixty undergraduate participants watched a video of a staged mugging and then answered questions about the video out loud in the presence of either one or three confederates who had also watched the film with them. Unbeknownst to the participant, the confederate(s) always gave incorrect responses to four out of the eight questions. Participants and confederates were also asked to give confidence scores out loud for each of their answers. Again, unbeknownst to the participant, the confederate(s) always expressed either high or low confidence scores for the incorrect information, depending on condition. Participants gave fewer correct answers, and were less confident, in the presence of three, as opposed to one, confederates. Participants were also more confident, yet no more accurate, when the confederate(s) gave high, as opposed to low, confidence scores. Thus the presumed independence of evidence given by multiple witnesses cannot be safely assumed.