Automatic detection of moral information: evidence from visual mismatch response (vMMR)

A theoretical debate persists regarding whether moral judgment is primarily driven by moral intuition or moral reasoning. Furthermore, it remains unclear whether moral information is processed automatically, despite the social intuitionist model's assertion that moral judgments arise from rapid, intuitive processes.

To investigate the automaticity of moral judgment, the present study employed the visual mismatch response (vMMR) as an electrophysiological marker. The vMMR is an event-related potential component that indexes the brain's automatic detection of environmental changes. Using a reversed block design, we presented moral and immoral stimuli while manipulating task relevance.

The results revealed that only immoral stimuli elicited an early vMMR, and its amplitude was unaffected by task relevance. In contrast, both moral and immoral stimuli elicited a late vMMR.

These findings suggest that the automatic detection of moral information, consistent with the notion of moral intuition, occurs during the early stage of moral judgment and operates as a highly automatic and negatively biased process. Moreover, the presence of both early and late vMMR indicates that moral judgment involves multi-stage automatic processing, encompassing both rapid deviance detection and subsequent, more elaborate automatic analysis.