Interoceptive Brain Processing Influences Moral Decision Making

Not harming others is widely regarded as a fundamental tenet of human morality. Harm aversion based on the consequences of an action is called utilitarianism while focusing on the action itself is associated with deontology. This study investigated how interoceptive processing affects the neural processing of utilitarian and deontological moral decision-making. The study utilized the heartbeat-evoked potential (HEP), an averaged electrophysiological component from electroencephalogram (EEG) to gauge cardiac interoceptive processing. Twenty-seven participants were asked to make utilitarian and deontological decisions for personal and impersonal moral dilemmas (18 for each) with direct and indirect harm actions, respectively, while their EEG and electrocardiogram were being recorded. We found no difference in HEPs between personal and impersonal moral dilemmas. In contrast, differential HEPs were observed between utilitarian and deontological moral decision-making, regardless of type of dilemmas. Significant differences were observed over centro-posterior electrodes between 110 and 172 milliseconds after R-peaks during the Scenario Phase, and over right fronto-temporal electrodes between 314 and 404 milliseconds after R-peaks in the Decision Phase. We confirmed that these differences in HEP amplitude between deontological and utilitarian decisions did not stem from cardiac artifacts. These findings reveal that the brain utilizes interoceptive information to make subsequent moral decisions.