Probability, danger, and coercion: A study of risk perception and decision making in mental health law.

Young adults were shown hypothetical stimulus vignettes describing mental patients and were asked to judge (a) the probability that the patient would harm someone else, (b) whether or not the patient should be categorized as “dangerous,” and (c) whether coercion should be used to ensure treatment. Probability and dangerousness judgments were systematically related and were predictive of the judged necessity for coercion. However, judged probability was strongly dependent on the form of the response scale, suggesting that probability was not represented consistently and quantitatively in participants' minds. Study 2 replicated these findings with forensic clinicians as participants. These results underscore the importance of violence to others in mental health law and have important implications for the manner in which risk assessments are formulated for use by the legal system.