Persuasive message effects on individuals versus interacting groups

The purpose of this dissertation was to examine the impact that a persuasive message has on group decision making among interacting face-to-face groups. The outcomes from these conditions were compared to those outcomes yielded from individuals' reactions to the same persuasive message. The logic underlying this approach is twofold: (1) To serve as a test of Petty and Cacioppo's Elaboration Likelihood Model generalizability to group behavior and, (2) to investigate the general question of whether groups and individuals process information in a similar fashion. The major dependent variables of interest were the degree to which subjects agreed with the arguments presented in the persuasive message, the valence of cognitive responses generated in reaction to the persuasive message, the extent to which individual group members influenced each other during group discussion, and the rate (in real time units) at which groups reached a decision.

The design called for the use of a three-way analysis of variance where the factors were (1) source credibility, (2) personal involvement of the subjects in the attitude issue and, (3) individual subjects versus interacting groups. These comparisons were made at three time periods—before group discussion, the groups' collective responses, and after group discussion.

The findings showed a partial confirmation of the hypothesis that groups and individuals would differ in their agreement with the persuasive message. Groups evidenced more message agreement after the conclusion of group discussion (i.e., as individuals) relative to individuals after an elaborative reprocessing of the persuasive message. It was hypothesized that the groups' collective responses would differ from those of individual subjects responding alone. Such an effect was not evidenced from the data.

Results also showed that groups took longer to process the decision task as a function of the level of personal involvement in the persuasive message. Groups under the high personal involvement condition took longer to complete the task than did those subjects under the low involvement condition. It was also shown that the credibility manipulation had a greater impact on the way that individual group members influence the attitudes of each other during the process of group interaction than did the involvement manipulation.

These findings are discussed in terms of (a) the elaboration likelihood model, (b) social versus informational influences on group related attitude change and, (c) the nature of persuasive message effects on individuals versus interacting groups.