Witnesses may point out a suspect in an identification parade simply because of the way he looks. And may unwittingly book an innocent.
Initial research suggests that people are more likely to identify those they dislike and less likely to identify someone they like.
Jim Sauer of the University of Portsmouth in Britain said this 'liking bias' might explain a growing number of mistaken identification cases.
According to Sauer, such decisions are automatic and spontaneous rather than thought out, reports the Daily Mail.
Hartmut Blank, a memory specialist at the Portsmouth University, said: "It's natural that we don't enjoy creating trouble for someone we like by identifying them as a perpetrator. The feeling of liking can definitely influence judgment."
"The liking bias is a subtle effect otherwise the justice system would have long been aware of it.
"The legal system finds eyewitness identification evidence compelling but it has contributed to many wrongful convictions over the years. Most people think their memories are reliable but no one is exempted from this vulnerability," Blank said.