Differentiating Darkness: Decision-making Differences Between Psychopathy and Machiavellianism

Machiavellianism and psychopathy are correlated but distinct personality traits that are associated with interpersonal manipulation and selfish behaviors (Paulhus & Williams, 2002). Based on a recent meta-analytic review, researchers have questioned whether these traits are distinct (Miller, Hyatt, Maples-Keller, Carter & Lynam, 2016). These meta-analytic reviews, however, have largely been based on atheoretical studies examining the relationship of these traits with self-reported outcomes. The purpose of the present research was to directly test the differences between Machiavellianism and psychopathy with respect to fundamental decision-making processes. In study one, the difference between psychopathy and Machiavellianism was assessed in terms of passive avoidance learning (a core finding in psychopathy research). Results of study one indicates that Machiavellianism is not significantly related to the attentional deficits associated with psychopathy. Further, the effect of psychopathy on passive avoidance learning in this study is significantly affected by gender, highlighting the importance of considering gender in examining the attentional deficits considered to be a core feature of psychopathy. Study two compared the behavioral flexibility of those higher in psychopathy and Machiavellianism using a prisoner\u27s dilemma task. Contrary to previous research, there is not a significant effect of Machiavellianism or psychopathy on selfish behavior in a consequence free condition. However, it is likely this finding is due to infrequency of participants\u27 behaving selfishly in this study. Nevertheless, those higher in Machiavellianism did tend to behave less selfishly when they perceived their partner as valuable to their future success. The implications of these findings are discussed