Dr Seale-Carlisle

A team of researchers led by Dr Travis Seale-Carlisle collated expert opinion gathered from scientists from all over the world on a variety of eyewitness memory phenomena. They found an “almost unanimous” shift in beliefs about the relationship between eyewitness confidence and accuracy.

The research showed that in 2001, around 90 per cent of experts thought that the degree of confidence expressed by the eyewitness had little relationship to how accurate they ultimately were. This opinion has now flipped to around 90 per cent of experts agreeing that the higher the confidence of the eyewitness, the more likely they are to be accurate in their identification.

This is true if certain conditions are applied when collecting confidence and if the identity parade is administered properly. Another condition that the experts agree is crucial, is the time at which this confidence statement is collected. It is most informative of accuracy at the initial identification attempt – not later at trial, for example, which can occur months or even years after the crime occurred.

Psychologists who investigate eyewitness memory have periodically gathered their thoughts on a variety of eyewitness memory phenomena since the 1980s. However, the most recent survey of expert opinion of eyewitness memory phenomena was conducted more than 20 years ago in 2001. The team in Aberdeen sought to update this.

This new understanding of the relationship between confidence and accuracy is crucial for those in the legal system to know and understand, according to Dr Seale-Carlisle.

He said: “Psychologists who investigate eyewitness memory used to think that how sure a witness was – or their confidence in their eyewitness identification, was very weakly related to how accurate they were. These opinions may have influenced policy surrounding eyewitness identification procedures in the UK.

“Guidelines in Scotland, for example, encourage eyewitnesses to justify the reason they identified someone from the identity parade, but say nothing about asking eyewitnesses for their level of confidence in their identification.

“In England and Wales, the policies surrounding identity parades also remain silent about eyewitness confidence. However, we now know from this research that most psychologists in the field believe eyewitness confidence, when collected properly, to be a valuable piece of information.

“Most psychologists in the field also agree that it is most valuable when gathered as early as possible rather than further down the line such as in court. This survey shows that most experts have changed their thinking on this issue. These policies in England, Scotland, and Wales therefore need to change.

The solution, Dr Seale-Carlisle said, is simple: “In my opinion this is the most important piece of information the legal system can collect from eyewitnesses aside from who eyewitnesses identify – and the legal system in the UK does not currently collect it.

“The policy to refrain from collecting confidence is based on an outdated notion that experts today do not agree with.

“All it takes is a simple question: “How confident are you that this is the person who committed the crime?”

“The US Department of Justice recently updated their department-wide policy to encourage the collection of initial confidence, and we encourage the UK to do the same.”

The findings are published in full in Perspectives on Psychological Science.