Physiological tests of the cheater hypothesis for the Dark Triad traits: Testosterone, cortisol, and a social stressor

In order to test the cheater hypothesis in relation to the Dark Triad traits (i.e., psychopathy, narcissism, and Machiavellianism), we conducted (N = 25 men) a pre- and post-test assessment of testosterone and cortisol with a social evaluative stress (i.e., lying while being video-taped) in between. Machiavellianism was positively correlated with pre-test testosterone, while psychopathy and Machiavellianism were positively correlated with pre-test cortisol. Cortisol decreased in men who were higher in Machiavellianism immediately after completing the lie-task and the patterns for narcissism and psychopathy were in the same direction, suggesting that these individuals were less stressed after the two truths and a lie task. Testosterone increased in those high in psychopathy and narcissism post-task, possibly reflecting, at least among narcissists, their enjoyment of the challenge to deceive others. Results provide physiological support to the hypothesis of the Dark Triad traits represent a “cheater strategy”.