Group Affiliation influences Information Processing in Collective Decision-Making

Abstract

Group decision-making and group affiliation are typically addressed as separate research topics. Our research combines these two areas to comprehend how groups impact the processing and updating of information during collective decisions. We utilized a minimal group paradigm to establish various levels of group affiliations (first-level in-group, second-level in-group, and outgroup). Participants engaged in majority vote group decisions within these three different groups, along with solo decisions, in two pre-registered online studies on Prolific. Our studies applied established experimental paradigms in human individual behavior to explore group decision-making. In the first study, participants (N=380) performed a learning task that required them to select gambles (among two options) with higher probabilities of winning. In the second study, participants (N=300) completed a perceptual task where they judged the direction of random dots twice, enabling us to assess how initial group decisions influenced information updating based on new information. We observed general effects of group decisions, irrespective of group affiliation: group vs. solo decisions reduced the impact of recent events on information processing (Experiment 1) and updating (Experiment 2). Regarding the effects of group affiliation, participants tended to rely more on in-group judgments compared to out-group judgments only when facing uncertainty. These findings contribute to our understanding of the mechanisms by which groups influence information and misinformation processing.