Side- and similarity-biases during confidence conformity
Memory conformity may develop when people are confronted with some divergent memories of others in social situations and knowingly/unknowingly incorporate these exogenous memories into their owns. Earlier research suggests that memory conformity is more prominent in subjects who bear low confidence towards their memory accuracy. Nonetheless, it is unclear whether and how this subjective confidence may likewise be influenced by the confidence levels of others. Here, we followed participant’s confidence transformation quantitatively over three confederate sessions in a memory test. After studying a set of human motion videos, participants had to answer whether a particular video had appeared before by indicating their side (i.e. Yes/No) and the associated confidence rating simultaneously. Participants were allowed to adjust their responses as they were being shown randomly-generated confederates’ answers and confidence values. Overall, we found that participants tended to become committed to their side early on and gain confidence gradually over subsequent sessions. This polarizing behavior may be explained by two kinds of preferences: (1) Participant’s confidence enhancement towards same-sided confederates was greater in magnitude compared to the decrement towards an opposite-sided confederate; and (2) Participants had the most effective confidence boost when the same-sided confederates shared similar, but not considerably different, confidence level to theirs. In other words, humans exhibit side- and similarity-biases during confidence conformity. Interestingly, among our participants, those who built up their confidence upon others’ retained a higher level of flexibility to change than those who had strong initial confidence. Thus, confidence polarization may not be a totally irreversible trend.