Group decision, choice shift, and polarization in consulting, political, and local political scenarios: An experimental investigation and theoretical analysis

Abstract

Five-person groups discussed for 15- or 30-min one of three different decision tasks: a personal consulting, a political attitudinal, or a local political problem. Groups were instructed to consider themselves committees who were to achieve joint decisions on the matter. Eleven Social Decision Schemes (SDS), resulting in different predictions of group decisions, have been tested for systematic bias and precision. The Black-Median model turned out to be best fitting with regard to both criteria, indicating that the group decision can be described as the result of a voting over alternative courses of action. Additionally, individual shift and group choice shift were analyzed with regard to Persuasive Argument Theory (PAT) and the Black-Median Decision Scheme. In a correlational analysis no indications could be found for a PAT process, whereas the SDS Black-Median covaried with individual shift as well as with group shift.