Response time modelling reveals evidence for multiple, distinct sources of moral decision caution

In everyday life, moral judgments are frequently made in dynamic information environments, in which we are required to revise our first impressions after learning new information. Further, overly harsh moral judgments may damage social relationships. For these reasons, we often need to be cautious in our moral judgments, yet how caution impacts moral decision-making processes remains poorly understood. We investigated how moral valence-driven caution and contextual information expectancy-driven caution affect decision processes underlying moral judgements using the diffusion decision model (DDM) framework. Across two experiments, participants (N = 122) made moral judgements of others’ sharing actions. Prior to judging, participants were informed whether contextual information regarding the deservingness of the recipient would follow. We found that participants slowed their moral judgements when judging negatively valenced actions and when expecting contextual updates. Using a hierarchical Bayesian Markov Chain Monte Carlo estimation of the DDM, we showed that these changes can be accounted for by shifts in drift rate and decision bias (valence) and boundary setting (context), respectively. These findings demonstrate that moral decision caution can be decomposed into distinct aspects of the unfolding decision process: the widening of boundaries in response to contextual update expectancy which may serve to reduce erroneous responding in general; and decision bias shifts, which reflect additional guarding against erroneous judgements which are negative.