"The present study was designed to test the hypothesis that greater modification of perception of an objective stimulus in the direction of a common norm following presentation of individual estimates and their average, would be obtained in group-centered units than in leader-centered units." The principal difference between these two kinds of groups was that member-to-member verbal interaction was at a maximum in the former, and held to a minimum in the latter. The data seem to bear out the major hypothesis. (PsycINFO Database Record (c) 2006 APA, all rights reserved)