Analyser l’effet de la présence de données neuroscientifiques dans une expertise psychiatrique pénale sur la perception que les magistrats professionnels ont de la qualité, la scientificité, le caractère convaincant du raisonnement de l’expertise, ainsi que sur la situation pénale de la personne expertisée.

Cette étude a été conduite auprès de 41 magistrats français. Les magistrats devaient lire un cas clinique, résumant une expertise, avec ou sans données neuroscientifiques, puis répondre à différentes questions fermées et ouvertes. La moitié des magistrats a reçu un rapport contenant des données neuroscientifiques et l’autre moitié un rapport similaire, sans ce type de données. Des analyses statistiques permettant d’évaluer les liens entre les caractéristiques de l’échantillon et les réponses données (corrélations) et de comparer les résultats aux deux conditions ont été réalisées (t de student), ainsi que des analyses qualitatives, terminologiques et thématiques.

Les résultats montrent que l’expertise est perçue comme étant significativement plus pertinente, de meilleure qualité, plus objective, plus fiable, plus convaincante et plus scientifique lorsqu’elle contient des données neuroscientifiques. Les magistrats font davantage de liens entre les troubles évoqués et les actes, allant dans le sens d’une diminution de responsabilité pénale, lorsque l’expertise contient des données neuroscientifiques.

L’introduction de données neuroscientifiques dans une expertise psychiatrique « traditionnelle » modifie la perception que les magistrats ont de cette dernière. Ces résultats peuvent être mis en lien avec différents biais cognitifs décrits dans la littérature.

To analyze whether the judge's perception of the quality, and scientific basis of a psychiatric expert report of a criminal defendant can vary according to whether or not this evaluation includes neuroscientific data (a written description of a structural neuroimaging MRI scan) and their effects on the decisions made by judges. Experimental psychology has demonstrated a number of cognitive effects arising from exposure to neuroscientific explanations and/or neuroimaging data and which may bias judgments and lead to (mis)interpretations that can affect decisions. This research suggests that including neuroscience evidence in an expert report may impact they way the report is assessed by non-specialists, such as judges, whose work requires them to take into account such reports.

We conducted a study on 41 French judges in order to determine whether their perceptions of the expert report (objectivity, reliability, scientific basis, quality, relevance, credibility, and persuasiveness) and their assessment of risk of recidivism, link between the disorder and offense and the influence of expert report on their decision-making, vary according to whether or not the evaluation includes neuroscientific data. The magistrates had to read a clinical case, summarizing an expertise, with or without neuroscientific data, and then answer various closed (criteria were evaluated using 7-point Likert-scales) and open-ended questions (asking respondents to indicate the reasons underlying their Likert-scale responses). Half of the magistrates received report containing neuroscientific data and the other half a similar report, without this type of data. Quantitative analyses were carried out to assess the effect of the sample's characteristics on the responses given and to compare the results between the two conditions (correlation analyses and Student T). Qualitative analyses, terminological and thematic, were also carried out.

Quantitative and qualitative results show that the presence of neuroscience data in an expert report affects judges’ perceptions of the report and the magistrates’ perceptions of the link between disorder and offense. The judges considered the expert report including neuroscientific data to be more relevant, more objective, better quality, and more reliable than the report without such data. Furthermore, they found the expert's arguments to be more persuasive and that these arguments had a greater scientific basis when the report included neuroscientific data than when such data was absent. Moreover, this phenomenon was stronger in more experienced magistrates than in less experienced magistrates. The qualitative finding shows a greater ability to recognize shortcomings in expert reports when they do not contain neuroscience data. The Expert reports including neuroscience data are perceived as more scientific and objective.

The presence of neuroscience data in an expert report affects judges’ perceptions of that report. These effects may be related to cognitive biases described in the literature, in particular the perceived scientific nature of neuroscience data. If judges are aware of their limits when it comes to assessing technical data, they appear relatively unaware that scientific data can induce cognitive biases and thereby affect their perceptions of expert reports.