Psychopathy and malingering of psychiatric disorder in criminal defendants.

Because the use of deception is an important clinical characteristic of psychopathy, there is intuitive appeal to the idea that psychopathy and malingering are associated. There is, however, very little research showing that psychopaths are more likely to malinger. We classified a sample of criminal defendants as high, moderate, or low in psychopathy, based on PCL-R scores, and compared their scores on indices typically used to detect malingering on the MMPI-2, the PAI and the SIRS. The high psychopathy group scored significantly higher on the MMPI-2 F and F-K; the PAI NIM, and the SIRS, but not the MMPI-2 Fb, F(p), or the PAI RDF or Mal, lending some support for the DSM-IV recommendation that malingering should be considered whenever there is a diagnosis of antisocial personality disorder. Logistic regression analysis (LGA) revealed that Factor I but not Factor II of the PCL-R significantly discriminated malingerers from nonmalingerers with 75% correct classification. However, receiver operating characteristic (ROC) analysis revealed that psychopathy ratings had poor sensitivity and specificity in the detection of malingering. Calculation of the percentages of those exceeding accepted cut-offs on each of the malingering measures revealed that a high percentage of severe psychopaths did not attempt to feign psychiatric disorder. The results suggest that psychopathy is not a clinically useful indictor of malingering. The results are discussed in terms of confirmatory bias and the impact such a bias could have on the evaluation of criminal defendants.