When the killing has been done: Influences of personality on third-party judgment and punishment of homicides in moral dilemma scenarios

Killing people is universally considered reprehensible and evokes in observers a need to punish perpetrators. To investigate how observers’ personality influences their cognitive, emotional, and punishing reactions towards perpetrators, we analyzed data from 1,004 participants who responded to three scenarios describing deliberate killings from a third-party perspective. Utilitarian motive of killing and inevitability of harm varied systematically between scenarios. Participants’ moral appropriateness judgments, emotions towards perpetrators, and assigned punishments revealed complex scenario-personality interactions. Trait psychopathy led to more understanding emotions but harsher punishments in all scenarios. Regarding utilitarian killings, need for cognition led to milder punishments, whereas intuitive/authority-obedient thinking led to stronger negative emotions and harsher punishments. Other-oriented empathy, trait anxiety, and justice sensitivity did not account for differences in third-party punishments. Our findings highlight the importance of interindividual differences on moral decision making and sense of justice.