Temporal dynamics of explicit and implicit moral evaluations

Explicit moral evaluation is often accompanied with active attention and explicit responses to moral information, while implicit moral evaluation happens in passive attention and implicit response to moral information. Previous studies have pointed out the differences in the neural mechanisms underlying explicit and implicit moral processing on the spatial dimension, however, the temporal differences between these two processes have not been clear. This study aimed at comparing the temporal dynamics between explicit and implicit moral evaluation of harm/care-related moral scenarios with high/low emotional arousal by using event-related potentials (ERP) technique. The behavioral results showed that the accuracy of the explicit task is higher than that of the implicit task, especially for high-arousal moral actions. The ERP results mainly revealed that regardless of the task type, the brain responses to moral evaluations can be divided into early emotional arousal processing indexed by the frontal N1, moral intuition indexed by the frontal N2, and middle/late stages of processing integration of emotional arousal and moral cognition which involve elaborative processing and cognitive control, reflected by the frontal P2, parietal P3, parietal LPP, and FSW. Moreover, explicit and implicit moral evaluations mainly differed in the late stage of moral processing indexed by the P3, LPP and FSW. Our findings provide robust evidence for the "hybrid" model supposed by Huebner, which suggested that both explicit and implicit moral evaluations involved a complex interaction between emotional processes and moral cognition, and the later ERP results strongly supported that explicit and implicit moral evaluations represented two relatively independent processes, fitting the multinomial model supposed by Cameron.