Conformity among Cowitnesses Sharing Same or Different Information about an Event in Experimental Collaborative Eyewitness Testimony

Abstract

Using the Mori technique in which two different movies presented on the same screen were viewed separately by two groups without their noticing the duality, two experiments were carried out with 138 undergraduates in groups of varying sizes to examine the effects of cowitnesses with the same or different information on these witnesses' memory distortion. Exp. 1 investigated the cowitness effects in a one-versus-two situation, while Exp. 2 investigated the effects in a two-versus-two situation. Analysis showed isolated eyewitnesses who had no supporting cowitnesses changed their minds more frequently toward the majority and, when they had a cowitness who shared the same information, they tended to stick to their original reports even after being confronted with conflicting information in a discussion.