Forensic Psychology

Forensic psychology occupies the interface between psychological science and legal practice, applying theoretical models of cognition, emotion and behaviour to questions of evidence, responsibility and risk. Practitioners and researchers in this field support courts by assessing the reliability of witness testimony, evaluating the mental state and recidivism risk of offenders, advising on interview and interrogation methods, and examining how professionals themselves cope with exposure to distressing material. Beyond individual assessment, forensic psychology informs policy and procedure by revealing how cognitive biases and organisational factors can shape decisions at every stage—from crime‐scene analysis to courtroom verdicts. The discipline thus advances both public safety and the integrity of justice systems worldwide.

Research from Nature Portfolio

Analytical professionals working in criminal justice and related sectors often review graphic or traumatic content, yet the mechanisms that underlie their stress responses were poorly understood. A new model proposes that repeated exposure to violent material can trigger post‐traumatic stress reactions through disrupted memory processing, empathic overarousal and maladaptive coping strategies. By integrating established theories of trauma with qualitative accounts from investigative staff, this work identifies critical points for resilience training and organisational support.

In the domain of eyewitness identification, a novel application of a two‐high‐threshold model directly measures biased suspect selection from actual witness decisions rather than from mock tasks. When standard photo lineups include subtly altered fillers, pre‐lineup instructions that discourage rejection amplify suspect‐selection bias. Restoring typical procedural safeguards—such as emphasising a right to say “not present”—eliminates biased choices. This approach establishes a quantitative framework for gauging lineup fairness and refining police protocols.

Research from all publishers

Firearms examiners demonstrate exceptionally low rates of false identification when comparing bullets and cartridge cases, yet the prevalence of inconclusive determinations rises sharply with case difficulty. A controlled study of trained experts reported conclusive error rates below 1 per cent, but noted that inconclusive outcomes occurred much more often on different‐source comparisons, underscoring the need to interpret results in light of both conclusive and inconclusive findings.

Similarly, a large‐scale investigation of cartridge‐case comparisons under field conditions found that, although conclusive identifications accurately reflected ground truth over 99 per cent of the time, including inconclusive decisions reduced true‐positive and true‐negative rates substantially. Importantly, even inconclusive judgments carried measurable evidential value, prompting calls for reports that explicitly communicate probabilistic strength rather than categorical assertions of match or non‐match.

In forensic handwriting examination, document experts were surveyed across hundreds of comparisons, revealing false‐positive rates of around 3 per cent on non‐matching samples and false‐negative rates of about 1 per cent on matching samples. Error patterns varied with examiner training and case complexity—twins’ handwriting proved especially challenging—highlighting how formal education and experience shape decision criteria in jurisdictions worldwide.

Forensic Psychology publication trend

The graph below shows the total number of articles in forensic psychology across all publications each year (not limited to Nature Index journals).

Technical terms

Secondary traumatic stress: Psychological distress resembling post‐traumatic stress disorder that arises from indirect exposure to traumatic events, common among professionals reviewing graphic evidence.

Lineup fairness: The degree to which no single lineup member stands out to a witness, ensuring each has an equal chance of selection.

False positive error rate: The proportion of non-matching samples incorrectly identified as matches by a forensic examiner.

Inconclusive decision: A forensic judgment that evidence is insufficient to support either a match or a non-match finding.

Biased suspect selection: Increased likelihood of identifying a suspect when procedural cues or lineup composition signal that one individual “must” be the perpetrator.

Likelihood ratio: A quantitative measure comparing the probability of observing the evidence under competing hypotheses (e.g. same‐source versus different‐source).

References

1. A model for secondary traumatic stress following workplace exposure to traumatic material in analytical staff. Communications Psychology (2024).
2. Measuring lineup fairness from eyewitness identification data using a multinomial processing tree model. Scientific Reports (2023).
3. Accuracy of comparison decisions by forensic firearms examiners. Journal of Forensic Sciences (2022).
4. Validity of forensic cartridge-case comparisons. Proceedings of the National Academy of Sciences of the United States of America (2023).
5. Accuracy and reliability of forensic handwriting comparisons. Proceedings of the National Academy of Sciences of the United States of America (2022).