<P> The PCL was originally developed in the 1970s by Canadian psychologist Robert D. Hare for use in psychology experiments, based partly on Hare's work with male offenders and forensic inmates in Vancouver, and partly on an influential clinical profile by American psychiatrist Hervey M. Cleckley first published in 1941 . </P> <P> An individual's score may have important consequences for his or her future, and because the potential for harm if the test is used or administered incorrectly is considerable, Hare argues that the test should be considered valid only if administered by a suitably qualified and experienced clinician under scientifically controlled and licensed, standardized conditions . Hare receives royalties on licensed use of the test . </P> <P> In psychometric terms, the current version of the checklist has two factors (sets of related scores) that correlate about 0.5 with each other, with Factor One closer to Cleckley's original personality concept than Factor Two . Hare's checklist does not incorporate the "positive adjustment features" that Cleckley did . </P> <P> The PCL - R is used for indicating a dimensional score, or a categorical diagnosis, of psychopathy for clinical, legal or research purposes . It is rated by a mental health professional (such as a psychologist or other professional trained in the field of mental health, psychology, or psychiatry), using 20 items . Each of the items in the PCL - R is scored on a three - point scale according to specific criteria through file information and a semi-structured interview . </P>

Research shows that high scores on the pcl-r are associated with