Lay decision-making and the insanity defense: The impact of evidence, judicial instructions, case construals, and attitudes on attributions of criminal responsibility

The first question in this research was: How do variations in jurisprudentially relevant cues affect responsibility judgments? Information reflecting two levels each of thought disorder, behavioral planfulness, and judicial instructions was varied to create a matrix of experimental vignettes which were administered to 145 undergraduate subjects in a between-subjects design. Thought disorder and degree of planfulness affected several relevant attributional measures of criminal responsibility, but accounted for comparatively little of the variance in the predeliberation verdicts. Differences in judicial instructions and verdict form accounted for more of the verdict variance, with the guilty but mentally ill (GBMI) form significantly reducing the probability of Guilty and NGRI verdicts in comparison with traditional Model Penal Code instructions. Subjects reaching GBMI verdicts were not more confident of their decisions. Thought disorder affected perceptions of the defendant's capacity for appreciation of and control over his behavior; planfulness affected perceptions of the defendant's capacity for appreciation of the wrongfulness of his conduct but not of capacity for control; and judicial instructions affected ratings of the defendant's capacity for control over his behavior. The second question was: How do case construals relate to verdicts? Post-verdict case construals were much more highly related to verdicts than were the experimental manipulations, suggesting that the construal of information presented at trial is more determinative of predeliberation verdicts than is the objectively presented information itself. A third objective was to measure attitudes towards the insanity defense and punishment, and to examine their relations with decisional behavior. A second sample ($n$ = 64) in which attitudes were measured before exposure to experimental vignettes was contrasted with subjects who rated attitudes after exposure to vignettes in order to gauge differences in attitudes and in the relations of attitudes to behavior under the two conditions. Results showed that attitudes were not affected by the experimentally varied cues in the vignettes but were strongly related to attributions of criminal responsibility in the post-exposure and weakly related in the pre-exposure conditions. Attitudes were significantly more negative, and the probability of reaching NGRI verdicts was significantly reduced, in the pre-exposure conditions.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Psychology

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Roberts, Caton Forest

• Law
• Psychology, Social
• Psychology, Clinical

Statement dc:rights

• Copyright 1989 Roberts, Caton Forest

Language dc:language

eng

Identifier

AAI8924931
(UMI)AAI8924931

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/23304