The new ESRC funded research at the Department of Psychology, University of Aberdeen used videotaped simulated crime events followed by photo line ups. Delay between exposure to the event and identification of the subject varied from approximately 40 minutes to around 48 hours. 'Our research was motivated by laboratory studies on the effects of ageing on the ability of adults aged over 60 to accurately recognise the faces of strangers' says Dr Memon.
The first of the four studies looked at how participants were affected by seeing mug-shots before identification. Half of a group of both young and old witnesses were shown mug-shots before watching a video of a car theft. 'Although none of the mug-shots actually showed the car thief, after a delay of 48 hours one of the innocent mug-shot faces was falsely picked out of an identification line up' explains Dr Memon. 'Prior exposure to mugs-hots increased false identifications of innocent people for both age groups with older adults making more false choices overall' she adds.
In another study, witnesses watched a video sequence where a man walked through a park and had a brief interaction with a young woman. A week later, participants were presented with a written account of the video either portraying the stranger in a positive or a negative light. 'Some participants were given an account which described the stranger as innocently meeting the girl for a date whilst others were told the man had assaulted the young woman' says Dr Memon. The positive story resulted in more positive statements about the stranger from all age groups.
However when older participants were asked to say whether or not the stranger was present in a photo identification parade the older group made more mistakes with those aged over 69 made 75% making more false choices. 'Although there were no age differences in the ability to identify whether or not the stranger was actually present in the identification parade an age related increase in false choices was clearly evident in the much older group of participants' says Dr Memon.
Another study focused on 60 older adults to find out their identification abilities. Participants met a confederate during which they had the chance to chat to her and an hour later were asked to pick her out of an identification parade even though she was not in it. 'Eighty seven per cent of these older participants falsely identified a face from the line up' says Dr Memon. 'This research seriously calls into question the age group used in identification parades and whether or not using mug-shots is actually helpful in identifying potential criminals' she adds.