Eye-witness identification may be attributed to bias

September 13, 2010

For the first time, eye-witness identifications are to be studied to determine if people avoid pointing the finger at someone they like in a police line-up.

Psychologists Dr. Hartmut Blank and Dr. Jim Sauer of the University of Portsmouth are studying eye-witness memory and ‘liking bias’ funded by a £100,000 Economic and Social Research Council grant.

Pilot research indicates people are more likely to identify line-up members they dislike as the of a crime and less likely to identify someone they like. Such decisions are automatic and spontaneous rather than thought out.

Dr. Blank is a specialist in memory and the effect of social influences on how and what we remember.

He said: “It’s natural that we don’t enjoy creating trouble for someone we like by identifying them as a perpetrator. Our contribution is to apply this insight to eye-witness identification because nobody has studied this before.

“The feeling of liking can definitely influence . The liking bias is a subtle effect though - otherwise the justice system would have long been aware of it.” Dr. Sauer is interested in the effect of liking bias because of the growing number of documented cases in which mistaken identifications contributed to the convictions of people who were later proved through DNA testing to be innocent.

He said: “The legal system finds eye-witness identification evidence compelling but it has contributed to many wrongful convictions over the years. “Eye-witness error represents a significant cost to society and . The first cost is an innocent person is jailed; the second cost is once an individual has been identified, police investigations may narrow, so the perpetrator remains at large.

“Most people think their memories are reliable but no-one is exempt from vulnerability to bias. Some people are more resistant than others; generally, those with better memories of an event are more resistant to biases, and those with poorer memories of an event are more vulnerable.

“In a police line-up, the witness goes in thinking they have a job to do. They assume the police have caught someone and that person is standing in the line-up. They also assume the police have other information to back up their arrest or suspicions. They think their job is to pick the suspect.

“If the eye-witness has no clear memory of the perpetrator, they look for cues available in the identification situation - perhaps subconsciously they just don’t like the look of someone in the line-up, so they point to them.”

The researchers will conduct four experiments trying to identify the underlying causes and boundaries of liking bias in the hope that they can then find ways of limiting or eliminating the effect of such bias in real-world identification procedures.

Explore further: Study: Traditional police lineups valuable

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