Social deficits associated with schizophrenia defined in terms of interpersonal Machiavellianism.

The social deficits of schizophrenia have been interpreted in an evolutionary context of Machiavellian social dexterity, stressing deficits in evolved psychological mechanisms that mediate the interpretation of affect and deceptive intention in others. A complementary hypothesis was tested, that patients with schizophrenia will be relatively non-Machiavellian compared to controls, and that social problems associated with the condition may reflect this relative social credulity. This hypothesis was addressed by assessing Mach IV psychometric scale performance in a group of 51 patients with schizophrenia and in 93 controls. Males, but not females, with schizophrenia scored significantly lower on the Mach IV scale than control groups. This result is interpreted in conjunction with the existing literature on social competence and sex differences in the symptomatology of patients with schizophrenia.