Abstract
4-person group and 2-person group had independently reached a pre-decision by choosing one from five alternatives, followed by a joint discussion to reach a final decision. The determinants of final decision and its implementation in group decision making were examined, focusing on the interpersonal influence process, 1) within both majority and minority, 2) between majority and minority in the joint discussion. interpersonal influence which results from the each speaker's intervention was measured in terms of change of preferences of the other members for each alternative. lt was found that groups, whose majority had showed average preference over a critical level for a minority's pre-decision at the outset of the joint discussion, finally adopted a minority's pre-decision, while the other groups adopted a majority's pre-decision. In the former groups, group memeber's interpersonal influence was higher, and the decision implementation was more frequent than in the latter. Furthermore, the amount of individual member's influence on the other positively related to the decision implementation in the former, but showed little relation in the latter.
