Thinking forensics: Cognitive science for forensic practitioners.

Human factors and their implications for forensic science have attracted increasing levels of interest across criminal justice communities in recent years. Initial interest centred on cognitive biases, but has since expanded such that knowledge from psychology and cognitive science is slowly infiltrating forensic practices more broadly. This article highlights a series of important findings and insights of relevance to forensic practitioners. These include research on human perception, memory, context information, expertise, decision-making, communication, experience, verification, confidence, and feedback. The aim of this article is to sensitise forensic practitioners (and lawyers and judges) to a range of potentially significant issues, and encourage them to engage with research in these domains so that they may adapt procedures to improve performance, mitigate risks and reduce errors. Doing so will reduce the divide between forensic practitioners and research scientists as well as improve the value and utility of forensic science evidence.

The impact of misinformation presented during jury deliberation on juror memory and decision-making.

When deliberating, jurors may introduce misinformation that may influence other jurors' memory and decision-making. In two studies, we explored the impact of misinformation exposure during jury deliberation. Participants in both studies read a transcript of an alleged sexual assault. In Study 1 (N = 275), participants encountered either consistent pro-prosecution misinformation, consistent pro-defense misinformation, or contradictory misinformation (pro-prosecution and pro-defense). In Study 2 (N = 339), prior to encountering either pro-prosecution or pro-defense misinformation while reading a jury deliberation transcript, participants either received or did not receive a judicial instruction about misinformation exposure during deliberation. Participants in both studies completed legal decision-making variables (e.g., defendant guilt rating) before and after deliberation, and their memory was assessed for misinformation acceptance via recall and source memory tasks. In Study 1, misinformation type did not influence legal decision-making, but pro-prosecution misinformation was more likely to be misattributed as trial evidence than pro-defense or contradictory misinformation. In Study 2, pro-defense misinformation was more likely to be misattributed to the trial than pro-prosecution misinformation, and rape myths moderated this. Furthermore, exposure to pro-defense misinformation skewed legal decision-making towards the defense's case. However, the judicial instruction about misinformation exposure did not influence memory or decision-making. Together, these findings suggest that misinformation in jury deliberations may distort memory for trial evidence and bias decision-making, highlighting the need to develop effective safeguards for reducing the impact of misinformation in trial contexts.

Self-administered mindfulness interventions reduce stress in a large, randomized controlled multi-site study.

Mindfulness witnessed a substantial popularity surge in the past decade, especially as digitally self-administered interventions became available at relatively low costs. Yet, it is uncertain whether they effectively help reduce stress. In a preregistered (OSF https://doi.org/10.17605/OSF.IO/UF4JZ ; retrospective registration at ClinicalTrials.gov NCT06308744 ) multi-site study (nsites = 37, nparticipants = 2,239, 70.4% women, Mage = 22.4, s.d.age = 10.1, all fluent English speakers), we experimentally tested whether four single, standalone mindfulness exercises effectively reduced stress, using Bayesian mixed-effects models. All exercises proved to be more efficacious than the active control. We observed a mean difference of 0.27 (d = -0.56; 95% confidence interval, -0.43 to -0.69) between the control condition (M = 1.95, s.d. = 0.50) and the condition with the largest stress reduction (body scan: M = 1.68, s.d. = 0.46). Our findings suggest that mindfulness may be beneficial for reducing self-reported short-term stress for English speakers from higher-income countries.

Does DNA evidence in the form of a likelihood ratio affect perceivers' sensitivity to the strength of a suspect's alibi?

Forensic expert testimony is beginning to reflect the uncertain nature of forensic science. Many academics and forensic practitioners suggest that forensic disciplines ought to adopt a likelihood ratio approach, but this approach fails to communicate the possibility of false positive errors, such as contamination or mislabeling of samples. In two preregistered experiments (N1 = 591, N2 = 584), we investigated whether participants would be convinced by a strong DNA likelihood ratio (5,500 in Experiment 1 and 5,500,000 in Experiment 2) in the presence of varying alibi strengths. Those who received a likelihood ratio often concluded that the suspect was the source of the DNA evidence and guilty of the crime compared with those who did not receive a likelihood ratio-but they also tended to conclude that an error may have occurred during DNA analysis. Furthermore, as the strength of the suspect's alibi increased, people were less likely to regard the suspect as the source of the evidence or guilty of the crime, and were more likely to conclude that an error may have occurred during DNA analysis. However, people who received a likelihood ratio were actually more sensitive to the strength of the suspect's alibi than those who did not, driven largely by the low ratings in the strongest alibi. Interestingly, the same pattern of results held across both experiments despite the likelihood ratio increasing by two orders of magnitude, revealing that people are not sensitive to the value of the likelihood ratio.

Open forensic science.

The mainstream sciences are experiencing a revolution of methodology. This revolution was inspired, in part, by the realization that a surprising number of findings in the bioscientific literature could not be replicated or reproduced by independent laboratories. In response, scientific norms and practices are rapidly moving towards openness. These reforms promise many enhancements to the scientific process, notably improved efficiency and reliability of findings. Changes are also underway in the forensic. After years of legal-scientific criticism and several reports from peak scientific bodies, efforts are underway to establish the validity of several forensic practices and ensure forensic scientists perform and present their work in a scientifically valid way. In this article, the authors suggest that open science reforms are distinctively suited to addressing the problems faced by forensic science. Openness comports with legal and criminal justice values, helping ensure expert forensic evidence is more reliable and susceptible to rational evaluation by the trier of fact. In short, open forensic science allows parties in legal proceedings to understand and assess the strength of the case against them, resulting in fairer outcomes. Moreover, several emerging open science initiatives allow for speedier and more collaborative research.

Beliefs about error rates and human judgment in forensic science.

Forensic science techniques are often used in criminal trials to infer the identity of the perpetrator of crime and jurors often find this evidence very persuasive. Unfortunately, two of the leading causes of wrongful convictions are forensic science testing errors and false or misleading forensic testimony (Saks and Koehler, 2005). Therefore, it is important to understand jurors' pre-existing beliefs about forensic science, as these beliefs may impact how they evaluate forensic evidence in the courtroom. In this study, we examine people's perceptions of the likelihood of error and human judgment involved at each stage of the forensic science process (i.e., collection, storage, testing, analysis, reporting, and presenting). In addition, we examine people's perceptions of the accuracy of - and human judgment involved in - 16 different forensic techniques. We find that, in contrast to what would be expected by the CSI effect literature, participants believed that the process of forensic science involved considerable human judgment and was relatively error-prone. In addition, participants had wide-ranging beliefs about the accuracy of various forensic techniques, ranging from 65.18% (document analysis) up to 89.95% (DNA). For some forensic techniques, estimates were lower than that found in experimental proficiency studies, suggesting that our participants are more skeptical of certain forensic evidence than they need to be.