Constructing insanity: jurors' prototypes, attitudes, and legal decision-making

Research consistently indicates that jurors' intuitive prototypes of insanity and case-relevant attitudes shape their verdicts more strongly than legal definitions of insanity. Based on a sample of 113 prospective jurors, this study was designed to (a) assess the extent to which three prototypes of insanity held by jurors in a past study generalize to a sample of jurors in another state and (b) determine the relative influence of attitudes toward the insanity defense and prototypes of insanity on jurors' case judgments across four insanity case vignettes. Results suggest that jurors' attitudes toward the insanity defense affected case judgments so strongly (r = .41-.61) that they swamped efforts to assess jurors' prototypes of insanity. Further, jurors' prototypes of insanity offered little incremental utility beyond that of insanity defense attitudes. Implications for identifying biased jurors and potential interventions for bringing jurors' decisions into greater accord with the law are discussed.