Witnesses routinely pick out the wrong suspect during a police line-up according to a new study in the journal, Psychological Science, reports the New Scientist.
But the alarming thing—says the study's author, Daniel Wright—is the reluctance of police to reaffirm a witness' correct choice by questioning it.
Witnesses are often told when they have chosen the suspect. This only serves to reinforce their confidence and makes it impossible to tell if they are confident because they are certain or just because they happened to pick the suspect, says Wright. His research shows that witnesses are inaccurate at least 20 per cent of the time, and that simply measuring how confident they are helps to reduce reliance on inaccurate choices.
The article notes Wright has recommended the introduction of "confidence-measuring procedures" as part of a government review of police line-ups.