The effects of group conformity on the prototypical majority effect for confidence and response latency

The Prototypical Majority Effect (PME) refers to the observation that people endorse majority opinions faster and with greater confidence than minority opinions. Although the PME has been assumed to stem from social influence, recent studies showed that it can arise from internal processes underlying decision and confidence alone. We used a conformity paradigm adapted from Asch (1951) to examine the relative contributions of internal and external processes to the PME. Four participants responded in turn to items that had correct or wrong predetermined majority responses. A robust PME was observed before participants saw others' responses. Seeing these responses, however, increased endorsement, confidence, and speed. Notably, social influence had a considerably weaker impact when it ran counter to the consensus observed in its absence. Thus, internal processes underlying decision and confidence constrain the impact of social conformity. The failure to consider these processes leads to overestimating the magnitude of social influence.