The role of neurological and psychological explanations in legal judgments of psychopathic wrongdoers

Abstract

Although brain imaging has recently taken center stage in criminal legal proceedings, little is known about how neuroscience information differentially affects people’s judgments about criminal behavior. In two studies of community participants (N = 1161), we examined how mock jurors sentence a fictional psychopathic defendant when presented with neurological or psychological research of equal or ambiguous scientific validity. Across two studies, we (a) found that including images of the brain did not alter mock jurors’ sentencing judgments, (b) reported two striking non-replications of previous findings that mock jurors recommend less severe punishments to defendants when a neuroscientific explanations are proffered, and (c) found that participants rated a psychopathic individual as more likely to benefit from treatment and less dangerous when a neurological explanation for his deficits was provided. Overall, these results suggest that neuroscience information provided by psychiatrists in hypothetical criminal situations may not broadly transform mock jurors’ intuitions about a psychopathic defendant’s sentence, but they provide novel evidence that brain-based information may influence people’s judgments about treatability and dangerousness.

Keywords:

• Neuroscience
• dualism
• punishment
• sentencing
• psychopathy

Notes

1. In subsidiary exploratory analyses, we examined whether the effects differed as a function of age, education level, and political orientation, and no significant effects emerged (analyses are available from first author upon request).

2. One additional question was administered in Study 1 asking participants if they believed their punishment decision was fair. However, we ultimately ended up excluding the question from analyses because the question was not administered in Study 2 due to experimenter error. When including this factor in the present analyses, this question loaded on a factor along with the question relating to whether the punishment decisions served as an effective deterrent (See Supplementary Material). Still, we found no significant main effect of neurological explanations or image inclusion (or an interaction) when examining judgments on the two questions that loaded onto this factor.

3. Factor and subsequent analyses were conducted including only the people who scored highly on the comprehension test. Each test was also re-conducted with the entire data-set, and no meaningful differences were found.

4. In exploratory analyses, we examined the Explanation-Type x Image Inclusion x Dualism interaction and each two-way interaction via MANCOVA while including Dualism scores as an interaction term. None of the results were significant and analyses are available from the first author upon request.

5. For all analyses presented here, we examined whether the effect of explanation type differed as a function of age, education level, political orientation, ethnicity, and whether participants had served on a jury. No significant effects emerged (analyses are available from first author upon request).

6. We administered an additional punishment questionnaire (Tyler & Weber, 1982) to assess attitudes toward the death penalty because we predicted that attitudes towards punishment more generally may influence sentencing judgments (Webster & Saucier, 2015). The death penalty beliefs measures asked participants three questions probing under what circumstances (e.g. murder, kidnapping, kill) the death penalty is justified. The responses to these three questions were averaged to create a composite death penalty belief score, with higher scores representing someone who strongly believes that the death penalty is justified in many circumstances (α = .87).

When we examined the effect of neurological explanations on sentencing judgments while controlling for beliefs in the death penalty, no significant differences emerged, F(2, 393) = 1.302, p = .273.

7. Given that we hoped to replicate the Dualism x Explanation-Type interaction from Study 1, we administered the additional dualism measure in Study 2 (Forstmann, Burgmer, & Mussweiler, 2012; Schubert & Otten, 2002). The dualism measure presented participants with two circles that become progressively closer across four depictions. One circle is labeled mind and the other is labeled brain. Participants were asked to pick which picture best represented their understanding of the relation between mind and brain. When using the pictoral measure as an interaction term, there was also no significant Dualism x Explanation-type interaction, F(2, 393) = 2.282, p = .103.