Making of a mistake: UK police lineups deliver significantly worse results than US equivalent, new research shows

Both UK and US police forces regularly use lineups to enable eyewitnesses to identify suspects. Researchers from Royal Holloway, University of London and the University of California, San Diego compared the ways in which these lineups are administered, testing which procedure harnessed the most accurate results. The UK's method proved much less accurate than the US counterpart, leading the researchers to argue for more scientific methods of eyewitness investigation.

The characteristics of an accurate lineup

In the UK, police generally conduct lineups using videos, shown one after the other of eight 'filler' individuals and one suspect. Each video lasts up to 15 seconds and the eyewitness asked to make their choice at the end of the sequence. One possibility is that this can lead to the witness losing attention, as the procedure takes around six minutes to complete.

In the US, still photographs are used -- shown simultaneously and with fewer options, usually five fillers and one suspect who can be chosen from within seconds.

Using a method of statistical analysis known as receiver operating characteristic (ROC) the researchers were able to show that this second method of simultaneous lineup outperforms the sequential procedure.

The experiment involved 2,249 participants watching a video of a mock burglary. They were then asked to choose the suspect from a lineup using either a six-person simultaneous photo procedure or a nine-person sequential video lineup.

Mistakes and misdirection

Psychologist, Dr Laura Mickes, Royal Holloway explained, "The use of lineups in criminal investigations has been controversial for decades, with plenty of cases of mistaken identity and wrongful convictions attributed to their use. The issue has recently been bought to the fore again with the massive popularity of the TV series 'Making of a Murderer', in which an American rape suspect spent 17 years in prison, having been wrongfully picked out of a lineup."

"Eyewitness evidence has been shown to be open to suggestion and misremembering but is still a vital tool in identifying criminals," continued Mickes, "What we must do is ensure that the ways in which we present lineups are conducted in ways that bring about the most accurate results."

Seeing science as the answer

Dr Mickes and her colleagues are calling on agencies to reconsider the ways in which police procedures are developed, arguing that a more scientific approach is needed to ensure justice is done.

"Lineups in the UK and in the US were not developed by scientists and then implemented in the field, but were created by law enforcement agencies who have no objective bias for preferring one method over another. The best way to determine what works accurately and fairly is through scientific analysis."