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UBC Theses and Dissertations

The validity of lie detection with criminal psychopaths Patrick, Christopher John


The idea that psychopaths may be able to "beat" a standard polygraph ("lie detector") test remains a controversial issue. The one published study to date that has addressed this question directly (Raskin & Hare, 1978) has been challenged on the grounds that: 1) the polygraph testing situation lacked a 'realistic threat component, and 2) the examiner's decisions were not based on blind chart analyses (Lykken, 1978). The present study re-assessed the accuracy of the polygraph with psychopaths using a revised procedure, in response to Lykken's criticisms. Subjects were 24 psychopathic and 24 nonpsychopathic male prison inmates (aged 18-54) selected on the basis of psychopathy checklist scores (Hare, 1980) and DSM-III ratings within each diagnostic sample, equal groups of "guilty" and "innocent" subjects were tested regarding their involvement in a mock theft by experienced professional polygraphers using control question procedures. Methodological innovations included: a) a "group contingency threat" manipulation which produced a realistic motivational; atmosphere for the polygraph test, b) simultaneous recordings of physiological activity on field and laboratory polygraph instruments, and c) blind numerical analyses of the field polygraph charts. Consistent with Raskin and Hare's results, the guilty psychopaths in the present study were detected just as easily as the guilty nonpsychopaths, and the majority of guilty subjects (87%, excluding inconclusives ) were correctly identified, even when the decisions were based on blind chart analyses. However in contrast to Raskin and Hare's 91% accuracy figure for innocent subjects, the overall hit rate for innocent subjects in the present study was only 56%. Quantitative analyses of the laboratory polygraph recordings revealed few meaningful differences between psychopaths and nonpsychopaths, and the results for guilty and innocent subjects closely matched those obtained with the field polygraph. The findings were discussed in terms of their implications for the field validity of the control question test and the responsivity of psychopaths to threat.

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