Demonstrating Group Polarization

Peter Gray (1993) suggests a simple exercise that readily demonstrates the group polarization effect. Before lecturing on group decision making in Chapter 15, have your students declare on a Likert scale how strongly they agree or disagree with some statement or idea (Gray suggests the idea that the next exam should be essay rather than multiple choice). Collect the responses and divide students into like-minded groups for a short, 5-minute discussion. After the group discussion, have students rate their agreement with the proposition again on the same Likert scale. The results should be consistent with group polarization: those who initially agreed should agree more strongly after group discussion, and those who initially disagreed should disagree even more strongly after group discussion. According to Gray, asking your students to speculate about the causes of the effect should generate the same explanations generated by psychologists over the years (i.e., that members are exposed to new, persuasive arguments, and that members gradually take a more extreme position in order to be viewed positively by others). An added benefit is that, in addition to learning the group polarization effect in a memorable way, students learn that they can successfully "think like psychologists" in generating plausible explanations for observed events.

Gray, P. (1993). Engaging students' intellects: The immersion approach to critical thinking in psychological instruction. Teaching of Psychology, 20, 68-74.