Self-reported personality traits in forensic populations: a meta-analysis

The current study covers a systematic review and meta-analysis of the prevalence of self-reported deviant or disruptive personality traits: anger, aggression, hostility, antisocial traits, psychopathy, and impulsivity in forensic populations worldwide. A computer-based search of titles was carried out using the PubMed electronic database for articles published in English that included a self-report instrument for personality characteristics in combination with a forensic population (i.e. detained in remand, sentenced and/or in enforced treatment, or on parole). The final sample consisted of 39 studies (N=11,716) that together used 17 different instruments and reported on 32 subscales or constructs that fitted our current interest. Results showed significantly higher levels of self-reported antisocial and psychopathic features in forensic samples, including a significant effect of the assessment instrument and subscale used. No significant differences were found for self-reported impulsivity, anger, aggression, or hostility in forensic populations compared to norm scores of non-forensic samples. Possible explanations, including suggestions that forensic populations are prone to providing socially desirable answers on self-report questionnaires, possibly to gain advantages such as a lower prison sentence or to avoid enforced treatment, are discussed, as well as limitations, and suggestions for future research and clinical practice.