The Dark Triad of personality and unethical behavior at different times of day

• We assessed the Dark Triad and unethical behavior at different times of day.
• In contrast to previous studies, time of day did not influence unethical behavior.
• Machiavellianism and psychopathy were differentially related to unethical behavior.

The Dark Triad of personality – narcissism, Machiavellianism, and psychopathy – is characterized by callous manipulation and social exploitation. Thus, dark personalities should be more prone to unethical behavior. Unethical behavior has been shown to vary during the course of the day with individuals displaying lower morality in the evening (Morning Morality Effect, MME). Hence, the present study investigated the association between the Dark Triad and unethical behavior as a function of time of day in an experimental design. Participants (N = 195) completed the study either in the morning or in the evening. In one task, participants had the choice to cheat on a fictitious partner for monetary benefit at the partner's expense. In a second task, they had the opportunity to lie about their performance for personal gain. Machiavellianism scores positively predicted unethical behavior in the first task. In the second task, psychopathy scores positively predicted lying. Neither could the MME be replicated, nor did time of day moderate the influence of the Dark Triad on unethical behavior. Thus, the present study indicates that the dark traits are differentially related to aspects of unethical behavior, such that Machiavellians display a preference for complex deception, while psychopaths engage in impulsive cheating.