Abertay-led team develops new tool to ‘freeze’ crime-scene memories

The tool, developed by a team led by the University of Abertay Dundee, combats natural memory decay by using the latest cognitive psychology techniques.

Witnesses use a self-administered interview (SAI) to 'freeze' images and details of crime scenes and perpetrators in their minds, particularly small and seemingly insignificant details that often turn out to be crucial in solving cases.

Tests at simulated crimes scenes showed that witnesses using the tool reported 42% more information that was forensically relevant and accurate than other witnesses who were simply asked to 'report as much as you can remember'.

The tests also revealed that witnesses using SAI recorded 44% more personal details about other people – ie, possible suspects – who had been involved in the event.

In another test, researchers waited seven days after an event before asking witnesses to provide a full account. Half of the witnesses had completed SAIs just after the event, while the others had given only their names and contact details. A week later, those who had completed the SAI were still reporting almost 30 per cent more correct details than those who had not.

The SAI protocol tool has been developed by Dr Fiona Gabbert from the University of Abertay Dundee, supported by Dr Lorraine Hope (University of Portsmouth) and Professor Ronald Fisher (Florida International University), supported by a £55,622 grant from the British Academy.

Dr Gabbert’s team worked with police forces in Scotland and England to develop the witness ‘recall and report’ tool to record memories at the earliest possible opportunity – at the scene of the incident.

Dr Gabbert said the completeness and accuracy of eyewitness evidence decreases over time: the longer the gap between witnessing an event and fully recalling it under formal interview conditions, the less accurate and less complete a witness report is likely to be.

“Decades of research in cognitive psychology demonstrate that memory decay, or forgetting, occurs rapidly at first. In a witnessing situation, this ‘forgetting’ will occur naturally and within hours of the incident. As the delay between witnessing and formal interview increases to days, memory decay will level off. However, by that time, many useful and forensically relevant details or clues may be lost forever,” she said.

Dr Gabbert said the SAI tool could play a significant role for law enforcement as the benefits were obvious – witnesses have the opportunity to record their memories before any potentially crucial information is forgotten.

“The forensic implications of these findings for current police practice are considerable. At present witnesses are likely to engage in a very brief initial interview prior to giving a full statement at some later date. This very brief initial interview may actually have a detrimental effect on the ability of a witness to fully recall the incident at a later occasion. In other words, only the memory for the brief outline is strengthened – not the memory for the details, which can sometimes become harder to recall as a result,” Dr Gabbert said.

“Research has proven, however, that recalling an event before any substantial forgetting or memory loss has taken place means that the way the event is represented in memory is strengthened, making it easier to recall in future. In this way, an early recall attempt serves to protect or ‘freeze’ the memory against the course of natural forgetting.”

Dr Gabbert said using the techniques of the cognitive interview, and providing instructions to think carefully about the witnessing environment and report everything no matter how insignificant without resorting to guesswork, the SAI supports the witness in both the recall and reporting of as much information as possible before that information has been lost.