Development of a psychopathy self-report measure
Hill, James Kevin
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Psychopathy is a multifaceted disorder that has been defined using behavioral, affective and cognitive criteria. However, much research focuses on the behavior of the psychopath, typically using criminal samples. The purpose of the present investigation is the development of a self-report measure based on the core personality characteristics of psychopathy that can be applied to both incarcerated and non-incarcerated respondents. Based on a dimensional concept of personality, the Social Personality Inventory (SPI) measures the core of asocial personality, while focusing on both the intrapsychic and interpersonal manifestations of the psychopathy. The project was divided into a developmental stage and a confirmation stage. In the development stage, a small group of forensic clients (n = 13) and a larger group of university students (n = 288) were administered an experimental version of the SPI. Several other self-report personality measures were included in the package to enhance the convergent validity of the resulting inventory (California Personality Inventory - Socialization Scale; Narcissistic Personality Inventory; Interpersonal Adjective Scales - B5; Balanced Inventory of Desirable Responding). Based upon the results of this phase, the 46-item SPI was developed. The subsequent confirmation phase was subdivided into two stages. The first phase used university undergraduates (N = 402) to establish the internal consistency of the SPI (alpha =.89). A subset of this group (n = 75) also completed the SPI on a second occasion, thus providing and estimate of test-retest reliability (r =.83). A second university sample (N = 170) completed the SPI and the same set of self-report measures used in the development stage to assess the validity of the instrument. It appears that, among university students, the SPI measures hostile-dominant personality, with narcissistic elements that also relates to low conscientiousness and low socialisation. The final phase of the project applied the SPI to a forensic sample (N = 172) which established the internal consistency of the SPI in this group (alpha =.92). A subset of the forensic sample (n = 55) was also rated on Hare's psychopathy Checklist-Revised (Hare, 1991). The correlations between the SPI and PCL-R were nonsignificant. Several explanations for the low relationship between the two instruments are presented. Finally, the SPI is discussed with reference to its overall characteristics and potential future applications.