The Brain Basis Of Moral Judgment Based On The Doctrine Of Doing And Allowing: An ERP Study

In the present research, event-related potentials (ERP) were recorded to examine the neural mechanism of moral judgment under a moral dilemma paradigm. Previous studies found that more emotion related brain regions were activated for the personal moral dilemmas, while more cognition related brain regions were activated for the impersonal moral dilemmas. Based on these results, researchers proposed the dual-process theory of moral judgment which suggests both emotions and reasoning are engaged during the processing of moral judgment. The personal/impersonal distinction of moral dilemmas has been criticized for lacking of theoretical basis and data supports. The deficiency of evidence from time course also makes the dual-process theory less persuasive. According to the classical utilitarian principle and the DDA principle (doing harm is more unacceptable than allowing harm, namely, non-maleficence is a more basic moral requirement than beneficence) ofdeontology, we examined how people deal with a conflict between utilitarian outcome and the principle of non-maleficence, a conflict between utilitarian outcome and the principle of beneficence, and a no harm behavior, as well as the scalp event related potentials (ERP) during these three kinds of moral situations.We found that:(a) behavioral results:Facing a conflict with utilitarian outcome, people tended to be more disapproving to the doing harm behavior than the allowing harm behavior; it took more reaction time to agree with the doing harm decision than the allowing harm decision even for a utilitarian consideration; for the doing harm moral dilemma, people took more reaction time when they made a utilitarian choice than they gave up the doing harm behavior (b) ERP results:allowing harm behavior elicited more negative N400-like than doing harm behavior and no harm behavior; doing harm behavior elicited more negative N400-like than no harm behavior; doing harm behavior and no harm behavior elicited more positive LPP than allowing harm behavior; (c) the score of moral emotion preferences from moral judgment test (MJT) was significantly related to the amplitudes of N400-like and LPP components.Those results suggested that both utilitarian and deontological principles are very important moral rules. And our study verified the dual-process theory which claims moral judgment contains a fast emotional process from the bottom up, as well as a slower cognitive process from the up down. In the early stage of moral judgment processing, the moral intuition of approving no harm behavior makes least semantic processing involve in the no harm situation (manifest as the smallest N400-like effect) relative to the doing harm and allowing harm situations; though people dislike the doing harm behavior instinctively, they still want to save more lives which weakens such kind of intuition, so more semantic processing involves in the doing harm situation (manifest as bigger N400-like effect) than the no harm situation; for the allowing harm situation, which cannot arouse a direct emotional judgment, people invest more semantic processing to gain a better situational understanding, and help with the later moral judgment. In the late stage of moral judgment processing, the doing harm behavior and no harm behavior that are more personally significant get more attention resource than the allowing harm behavior (manifest as more positive LPP which reflect some kind of emotional regulation and cognitive evaluation). In addition, the moral emotion preferences can regulate the brain mechanism of moral judgment.