The Effects of Positioning on the Accuracy of Lineup Decisions.

Abstract

Lineup decisions can be crucial in deciphering whether a suspect is guilty of a crime or not. However, lineup decisions can often be inaccurate which can often result in innocent people being convicted of a crime. Previous research has investigated if the suspect's position in a sequential lineup has any effect on whether the suspect will be chosen or not. However, much of the research has used six-person lineups - the norm in North America - rather than nine-person lineups as is the norm in the UK. We manipulated the position of the suspect in target-present and target-absent sequential nine-person lineups. The experiment also investigated if there were any differences between viewing the lineup once versus twice. Whilst position and number of viewings had no effect on identification accuracy, significant results were found in confidence ratings which showed that confidence of correct decisions increased when the perpetrator was presented later in the lineup. Implications are discussed and it is suggested that future research is required to investigate the effects of positioning further.