How attitude strength and information influence moral decision making: Evidence from event-related potentials

Moral judgments are based on complex processing. This study aimed to investigate neural correlates of moral decisions. Participants (N=32) were asked to express their opinion on various moral issues while ERPs were recorded. After reading texts containing either confirming or contradicting arguments regarding the issues, participants were asked to express their opinion again. A higher N400 amplitude and a higher amplitude of the late positive potential for value-incongruent words compared to value-congruent words could be observed. Furthermore, after participants had read conflicting arguments, slower responses and larger N400 differences (value-incongruent minus value-congruent) were observed. These results showed that language processing for a moral context is influenced by the subjective value system, and it can be assumed that a demanding cognitive elaboration contributed to the observed RT and N400 priming effects. This is the first ERP study comparing moral judgments before and after reading confirming or conflicting information; it revealed that evaluative reasoning can influence neural processing for moral decisions.