Markus Germar

Building on the seminal studies of Solomon Asch and Muzafer Sherif, recent research has advanced our understanding of the mechanisms underlying social influence by applying a diffusion model analysis. Here, we combined the social identity approach to social influence with a diffusion model analysis to unravel the mechanisms underlying social influence. In particular, we aimed to disentangle whether the difference between in‐group and out‐group influence on perceptual decision‐making is driven by a judgmental bias (i.e., changes in decision criteria) or a perceptual bias (i.e., changes in the uptake of sensory information). Preregistered analyses indicated that in‐groups exerted stronger social influence than out‐groups because in‐groups induced a stronger perceptual bias than out‐groups. This finding is in line with the single process assumption of the social identity approach because it implicates that the single process driving social influence (i.e., self‐categorisation) translates into a change in a single subprocess of decision‐making (i.e., biased information uptake). In conclusion, our results highlight that our theoretical understanding of social influence can be expanded by integrating the social identity approach with a diffusion model analysis.