Effects of two procedural factors on group decision-making: Deliberation style and assigned decision rule

Many important decision making groups in our society are guided, formally or informally, by a variety of procedures that serve to facilitate the consensus process (e.g., quorum rules, voting procedures, fixed agenda). Despite abundant anecdotes concerning the procedural effects on group decisions and sophisticated formal developments by welfare economists, the number of relevant empirical studies on this issue is quite limited. This study examined procedural influences in a legal context. Six-person mock juries discussed two civil cases in which applicable law required either a conjunctive or disjunctive assessment of key evidence (i.e., proving either all or at least one legal criterion) to render a verdict of liability. Under these task requirements, jury deliberation style, analogous to the verdict-driven/evidence-driven distinction by Hastie, Penrod, and Pennington (1983), and official decision rule were manipulated. Consistent with predictions derived from Grofman's (1985) conceptual framework, deliberation style was found to interact with the task environment in affecting jury verdicts: the "elemental" (cf., evidence-driven) deliberation style yielded a liable verdict more often than the "compound" (cf., verdict-driven) deliberation style in the conjunctive case, whereas this pattern was reversed when the case required a disjunctive judgment. Although the decision rule factor (i.e., majority/unanimity) revealed no significant effect on group decisions, it affected members' postdecision responses (e.g., acceptance of the group decision, opinion change). Implications of these procedural influences for legal/administrative decision contexts were discussed.U of I OnlyETDs are only available to UIUC Users without author permissio