Kaplan, M. F., & Miller, C. E. (1977). Judgments and group discussion: Effect of presentation and memory factors on polarization. Sociometry, 40, 337-343.
Mock juries, composed of six females each, listened to a tape-recording of facts in a courtroom trial. Twelve juries heard incriminating facts, and twelve heard exonerating facts. In half the juries, all jurors heard the facts in the same (homogeneous) order; in the remaining juries, each juror heard the facts in a different (heterogeneous) order. Jurors individually rated the defendant’s guilt, then discussed the case as a jury, and again individually rated guilt. It was expected that a greater variety of facts would be remembered and shared during discussion under heterogeneous than under homogeneous order conditions and that this would lead to greater polarization of postdiscussion judgments under the former condition. This prediction was supported. The results suggest that, in cases where all group members are exposed to the same information, differential memory may be a mechanism for producing variety in the information shared during group discussion, and thus for enhancing discussion-induced judgment shifts.Deliberation induced polarization consistent with evidence strength, especially when all jurors heard evidence in same order. Facts from last third of trial most likely to be recalled during deliberation.