Dissociation between morality and disgust: An event-related potential study

• Morally wrong conditions elicited greater P300-400 than morally neutral conditions.
• Physically disgusting conditions elicited larger P500-600 than neutral conditions.
• Morality and disgust are neurologically dissociable in the temporal dimension.
• The detection of moral violations may occur earlier than that of disgust.

This study explored the neural correlates of morality and disgust, particularly, how the mechanisms that mediate our avoidance of physically disgusting and morally abhorrent behaviors are neurologically dissociated during the time-course of processing. Twelve participants were asked to judge the acceptability of different types of behaviors, which varied in their level of moral wrongness and physical disgust, while event-related potentials (ERPs) were recorded. The main results showed that the two morally wrong conditions elicited greater amplitudes of P300-400 at frontal sites than the neutral condition and the physically disgusting, but not morally wrong, condition. The physically disgusting conditions (with and without moral content) elicited significantly more positive deflections in the 500–600 ms timeframe than the neutral condition at central–posterior sites. These findings indicate that our aversion to harmful substances in the physical environment and offensive behaviors in the social environment may be neurologically dissociable in the temporal dimension. Furthermore, the detection of moral violations may be processed earlier in time than that of physical disgust.