Effect of word-list consistency on the correlation between group memory and group polarization.

Two studies investigated the effect of shared knowledge, manipulated using associated or randomly ordered word lists, on the correlation between group remembering and group polarization. Group polarization due to accumulation of information was expected only if it was consistent with shared knowledge among group members (the knowledge shared among group members before discussion). Consistency of information with shared knowledge was manipulated by lists of words that were ordered either randomly or in a manner consistent along with four stereotype categories. In Experiment 1, 159 college students answered a questionnaire about the common stereotype that blood type determines personality; half were given lists of words that were consistent with the stereotype (consistent condition) and the other half, randomly ordered word lists (inconsistent condition). After completion of the questionnaire, they were given, a surprise free-recall test including words from the lists that had appeared in the questionnaire; the test was administered in a group (group condition) or individual (individual condition) setting. The results indicated that stereotype-consistency of the word list reduced the groups' ability to detect incorrect answers compared with the individual condition. In Experiment 2 (N = 132), the divergence of memory among group members was manipulated by altering the constitution of each group with regard to members' blood type. The results showed that the shift in the score representing belief in the blood-type stereotype correlated with the number of words recalled in the stereotype-consistent word-list condition.