Enhancing Legal Interviews and Eyewitness Reliability with Forensic Psychology

A wrongful conviction can shatter a life. And more often than not, the chain of errors starts not in the courtroom but in the interview room – or at the scene where a witness first recalls what they saw. Forensic psychologists work at this critical junction, applying scientific research on memory, deception, and human behaviour to improve how law enforcement gathers information. Their contributions help ensure that interviews yield accurate accounts, that deception is assessed using evidence-based methods, and that eyewitness testimony is treated with the appropriate level of scrutiny.

Why traditional police interviews needed an overhaul 🔗

For decades, police interviews and interrogations in many countries relied on confrontational, pressure-based methods. The most well-known of these is the Reid Technique, which became the dominant approach in the United States starting in the 1950s. This method involves a guilt-presumptive, accusatory process in which the investigator tells the suspect that evidence clearly points to their involvement. The technique uses psychological pressure, including theme development, minimisation of the offence, and discouragement of denials, to move the suspect toward a confession.

The problem? This approach has been linked to a troubling rate of false confessions. A 2024 systematic review and meta-analysis published in Campbell Systematic Reviews found that accusatorial approaches produced significantly more false confessions compared to information-gathering methods. The same review concluded that accusatorial techniques have contributed to roughly 12% of known wrongful convictions in the United States. Forensic psychologists have been instrumental in documenting these failures and pushing for reform.

The cognitive interview: a psychology-driven alternative 🔗

One of the most significant contributions of forensic psychology to the interview process is the Cognitive Interview (CI), developed by psychologists Ronald Fisher and Edward Geiselman. Rather than pressuring interviewees, the CI uses principles of cognitive and social psychology to help witnesses retrieve memories more effectively.

Core techniques of the cognitive interview 🔗

The CI rests on several key techniques. First, the “report everything” instruction encourages witnesses to share all details, even those they consider unimportant. As the Open University’s forensic psychology course explains, members of the public often withhold information because they assume it is irrelevant or that police already know it. Training officers to explain that every detail contributes to a larger investigative picture significantly increases the quantity of useful information obtained.

Second, context reinstatement asks witnesses to mentally return to the environment where the crime occurred – the sights, sounds, smells, and their emotional state at the time. This technique leverages the well-established psychological principle of encoding specificity: memory retrieval improves when the conditions at recall match those at encoding.

Third, the CI includes the reverse-order technique, where witnesses recount events backward. This disrupts the tendency to rely on scripted or rehearsed narratives and often surfaces details that a chronological retelling would miss.

Laboratory tests of the CI conducted across the United States, England, Germany, and Australia have consistently found that it produces between 25% and 100% more correct statements than standard police interviews, while maintaining high accuracy rates. These results have made the CI one of the most well-validated tools in forensic psychology.

The PEACE model: building ethical interviews from the ground up 🔗

Beyond individual techniques, forensic psychologists helped develop the PEACE model – a comprehensive framework for investigative interviewing that originated in England and Wales in the early 1990s. PEACE is an acronym that stands for Preparation and Planning, Engage and Explain, Account, Closure, and Evaluation.

The model was created in direct response to several high-profile miscarriages of justice in the UK, including the Birmingham Six and Guildford Four cases, where confessions were later found to have been coerced. PEACE takes a non-confrontational, rapport-based approach that focuses on gathering accurate and complete information rather than extracting confessions.

How PEACE works in practice 🔗

During the Preparation and Planning stage, interviewers review all available evidence and plan their approach. The Engage and Explain phase is devoted to building rapport – introducing the purpose of the interview, addressing the interviewee’s welfare, and setting a cooperative tone. In the Account stage, the interviewee provides their narrative using open-ended questions, with the interviewer probing for clarification without leading the witness. Closure ensures the interviewee has nothing more to add, and Evaluation requires officers to assess the quality of the information obtained and their own interviewing performance.

Research has validated this approach. According to the FBI Law Enforcement Bulletin, the PEACE model focuses on determining relevant facts while encouraging interviewers to remain fair and open-minded. The model has been adopted by police forces in the UK, Australia, New Zealand, Norway, and parts of Canada, and is gaining traction in North America.

Detecting deception: what science actually says 🔗

One of the most persistent myths in criminal justice is that trained investigators can reliably tell when someone is lying by reading body language. Forensic psychology research has thoroughly debunked this idea.

The limits of human lie detection 🔗

Decades of research have shown that the human ability to detect deception is barely above chance level – typically around 54% accuracy, where 50% would be pure guessing. This finding holds even for experienced law enforcement professionals. People tend to rely on stereotypical cues like gaze aversion and fidgeting, but these behaviours are not reliably associated with lying. Nervousness, cultural differences, and individual personality all produce similar behaviours in truthful people.

The traditional polygraph, too, has significant limitations. While it measures physiological arousal, it cannot distinguish between the anxiety of lying and the anxiety of being falsely accused. This is why forensic psychologists have shifted focus toward more evidence-based approaches.

Cognitive load approaches 🔗

A more promising direction in deception detection is the use of cognitive load techniques. The underlying principle is straightforward: lying is mentally harder than telling the truth. A liar must suppress the true version of events, construct a plausible alternative, monitor the interviewer’s reaction, and maintain consistency – all simultaneously.

Research published in Trends in Cognitive Sciences highlights that cognitive load approaches aim to exploit this mental burden by making the interview task more demanding. For example, asking a suspect to recount events in reverse order places additional strain on someone fabricating a story, making inconsistencies more likely to emerge.

Strategic use of evidence (SUE) 🔗

Another approach developed by forensic psychologists is the Strategic Use of Evidence (SUE) technique. In SUE, interviewers withhold known evidence early in the interview and allow the suspect to give their account freely. If the suspect is lying, their statement will often contradict the evidence the interviewer already holds. If truthful, their account is more likely to be consistent with it. Studies have shown that training interviewers in the SUE technique significantly improves deception detection accuracy compared to untrained control groups.

Eyewitness memory: reliable but fragile 🔗

Eyewitness testimony remains one of the most influential types of evidence in criminal trials. Juries tend to find it persuasive. But forensic psychology research has revealed just how easily eyewitness memory can go wrong.

How memory works – and fails 🔗

According to a review published in Frontiers in Psychiatry, eyewitness error was involved in approximately 75% of the first 312 DNA exoneration cases in the United States. The American Psychological Association estimates that roughly one in three eyewitnesses makes an erroneous identification.

Memory is not a video recording. It is a reconstructive process – every time we recall an event, we are actively rebuilding it, influenced by subsequent experiences, conversations, emotions, and even the way questions are phrased. Post-event information from media coverage, discussions with other witnesses, or suggestive police questioning can alter a witness’s memory without them even realising it. And once a memory is contaminated, the original version is extremely difficult, if not impossible, to recover.

Key factors that affect eyewitness accuracy 🔗

Forensic psychologists distinguish between two categories of variables that influence eyewitness reliability:

Estimator variables are factors that the justice system cannot control. These include the lighting conditions at the time of the crime, the distance between the witness and the perpetrator, the duration of exposure, the level of stress or fear the witness experienced, and the presence of a weapon. Research on the weapon focus effect, for instance, shows that witnesses who see a weapon tend to focus on it at the expense of other details, particularly the perpetrator’s face.

System variables are those that the justice system can control – and this is where forensic psychology has had its greatest practical impact. System variables include how police conduct interviews, how lineups are structured, and what instructions witnesses receive before making an identification.

The confidence-accuracy problem 🔗

One of the most dangerous findings in eyewitness research is the weak relationship between a witness’s confidence and their accuracy. A witness who says “I am absolutely certain that’s the person” is not necessarily more likely to be correct. Confidence can be inflated by confirming feedback (such as being told they picked the right person), by repeated questioning, or simply by the passage of time. As the British Psychological Society has noted, confidence is often treated as proof in courtrooms, despite decades of research warning that it should not be.

However, recent cognitive science research has added nuance to this picture. A 2025 review in Trends in Cognitive Sciences argues that eyewitness memory, like other forensic evidence, can be reliable if it is tested early in an investigation before contamination occurs. The initial, uncontaminated memory test tends to be far more accurate than later ones shaped by intervening events.

How forensic psychologists are improving the system 🔗

The practical contributions of forensic psychologists extend well beyond the research lab. They train police officers in evidence-based interview techniques. They serve as expert witnesses in court, educating juries about the limitations of eyewitness testimony and the psychology of false confessions. They develop and evaluate lineup procedures – such as recommending double-blind administration, where the officer conducting the lineup does not know which person is the suspect, eliminating the possibility of unintentional cues.

Forensic psychologists have also developed specialised interview protocols for vulnerable witnesses, including children, elderly individuals, and people with intellectual disabilities. The NICHD (National Institute of Child Health and Human Development) protocol, for example, is a structured forensic interview guide specifically designed for children, emphasising rapport-building, open-ended prompts, and developmentally appropriate language.

These contributions are not just academic – they directly impact whether investigations lead to the conviction of guilty individuals or the wrongful imprisonment of innocent ones. Every improvement in interview quality, every reduction in eyewitness contamination, and every move away from pseudoscientific deception detection brings the justice system closer to the accuracy it demands.

The road ahead 🔗

Despite significant progress, challenges remain. Many law enforcement agencies worldwide still lack training in evidence-based interview techniques. The Reid Technique remains widely taught in parts of the United States. Jurors continue to overvalue confident eyewitness testimony. And emerging technologies like AI-driven behavioural analysis raise new ethical questions about privacy, bias, and the appropriate role of technology in assessing truthfulness.

Forensic psychology will continue to be essential in navigating these challenges – grounding criminal justice practices in rigorous science rather than intuition, tradition, or convenience.

What do you think? How much weight should eyewitness testimony carry in a criminal trial when we know memory can be so easily distorted? And should countries that still rely on confrontational interrogation methods be required to adopt evidence-based alternatives like the PEACE model?

References

1. https://en.wikipedia.org/wiki/Reid_technique
2. https://pmc.ncbi.nlm.nih.gov/articles/PMC11465838/
3. https://www.open.edu/openlearn/mod/oucontent/view.php?id=68095&section=2.2
4. https://criminal-justice.iresearchnet.com/forensic-psychology/cognitive-interview/
5. https://www.caseiq.com/resources/investigative-interviewing-techniques-the-peace-model
6. https://leb.fbi.gov/articles/featured-articles/current-state-of-interview-and-interrogation
7. https://criminal-justice.iresearchnet.com/forensic-psychology/police-psychology/detection-of-deception-in-adults/
8. https://pmc.ncbi.nlm.nih.gov/articles/PMC4309739/
9. https://pmc.ncbi.nlm.nih.gov/articles/PMC4131297/
10. https://www.simplypsychology.org/eyewitness-testimony.html
11. https://www.open.edu/openlearn/mod/oucontent/view.php?id=68093&section=2.4
12. https://www.bps.org.uk/psychologist/rethinking-reliability-eyewitness-testimony
13. https://www.sciencedirect.com/science/article/pii/S1364661325000270
14. https://pmc.ncbi.nlm.nih.gov/articles/PMC10913353/