Investigating the multivariate relationship between impulsivity and psychopathy using canonical correlation analysis

Background Impulsivity is generally considered a core feature of psychopathy, however one problem with understanding the association between these constructs is that both are multifaceted. Existing research often treats one or both of these constructs as unidimensional with important information regarding the complex nature of the relationship being lost. To clarify this issue the present study employs a canonical correlation analysis (CCA) which allows for the comparison of two multifaceted measurement scales simultaneously. Methods Respondents (n = 970) completed the Barratt Impulsiveness Scale (BIS-11) and the Psychopathic Personality Inventory (PPI). CCA was performed to explore the strength and nature of the association between impulse control and psychopathy. Results There was a large correlation (r = 0.57) between BIS-11 and PPI total scores. Further exploration using CCA showed that 70.2% of the variance was shared between the subscales, and three significant canonical functions emerged. These were found to be interpretable and suggest that impulsivity relates to the broader psychopathy domain in a complex fashion, and that non-planning impulsivity may be the primary trait which distinguishes between psychopathy subtypes. Discussion The findings support a complex multi-dimensional relationship between impulsivity and psychopathy. The simple impulsivity-psychopathy correlation has much less explanatory power than has a multivariate approach.