News
Witnesses given new tool to fight gang crime
Wed, 20 Mar 2013 08:52:00 GMT
Witnesses to crimes involving gangs or several offenders are much more likely to remember who did what if they record what happened using a new timeline-based approach, according to new research.
The first study to test a timeline technique as a means of improving eyewitness memory performance was carried out by scientists at the University of Portsmouth.
The research, lead by applied cognitive psychologist Dr Lorraine Hope, of the Department of Psychology, is published in the Journal of Applied Research in Memory and Cognition.
Dr Hope and colleagues tested the memories of witnesses to a mock filmed crime using various interview and recall methods.
Those given the freedom to provide their report on a timeline from when the crime started to when it ended, using notes stuck to the timeline to indicate who did what and what happened, performed significantly better, remembering nearly 50 per cent more information, than those asked to recall facts in the ‘start at the beginning and tell me what you saw’ traditional interview approach.
Mock witnesses asked to recall on a timeline what they saw even two weeks after the ‘crime’ also outperformed other witnesses.
Dr Hope said: “The results are promising, particularly for multiple perpetrator crimes, with those using a timeline approach able to recall significantly more detail about who did what and when than those who were interviewed.
“Accurately recalling complex incidents with more than one person involved is extremely difficult for witnesses.
“Our research suggests people perform much better – they remember more and they make fewer errors – than when they are simply asked to report what they saw in an interview.”
Recalling detailed information about a witnessed event, such as a robbery, assault or other crime, has been shown to be a cognitively demanding task.
The researchers’ timeline approach fixes the time during which the crime or incident took place but allows people to move around the ‘who’ and the ‘what’ of a crime they’ve witnessed until they are satisfied with the accuracy of the ‘account’ of what they have witnessed.
Dr Hope said: “Traditional interviews often require that witnesses start at the beginning and keep going until the end, but this may not be the best way of helping people remember complex events with multiple perpetrators.”
In two experiments, nearly 200 people watched a video of a mock complex mugging and assault, resulting in a gang stealing a laptop from a women passerby.
Some of the research participants were asked to report details of the different people involved using one set of cards, while on another set of cards, report descriptions of what happened – the ‘who did what’. They were able to move the cards around on a fixed timeline in the appropriate order to help make it clear who did what and when. They were allowed to re-order the cards as many times as they wished until they were satisfied of the accuracy of their account.
Others taking part in the same experiment were asked to submit to a “start at the beginning and tell me what you saw” style of free recall interview.
Others were asked to not report anything straight away but to come back two weeks later and go through either the timeline or free recall interview techniques.
In comparison to the standard recall, research participants who provided their recall of the witnessed incident using the timeline technique reported 47 per cent more correct details when tested immediately and 32 per cent more correct details when tested after a tw0-week delay than participants who were simply asked to report what they had seen.
Dr Hope said: “It is likely the timeline technique reduces the constraints associated with linear ‘start-at-the-beginning’ approaches. The timeline technique reduces the cognitive load on the brain, people no longer have to hold details or rehearse them in their memory, instead they can record things immediately and put them into sequence later.”
The research has potential to be applicable to crime investigators especially in multi-perpetrator crimes, though it is still in the early stages of development and more research is needed.