The Effect of Serial Position on Lineup Decisions

Abstract

Incorrect eyewitness testimony causes many issues for the justice system - with the most severe being high numbers of incorrect prosecutions and this therefore calls for a redesign of the structure of lineups to assess what may be the cause of such inaccuracies. Positioning of targets within lineups has been theorised as being influential for witnesses identifications of potential perpetrators and is therefore the key area of investigation for the current study. Many studies have aimed to investigate whether there is a serial position effect observed in recall for list items, but very few have investigated whether said serial position effect can also be reported in tests of recognition - specifically, within lineup decisions. To gain a better insight into the possibility of such effects, we assessed the influence of target position on 72 participants' recognition for the target, whilst also recording potential influences on accuracy through one or two lap viewing of lineups. The results revealed non-significant results for position or lap viewings on accuracy of identifications, but instead reported significant results for confidence within accurate decisions when influenced by position of target within target present lineups - although both target-present and target-absent lineups were tested. It was proven that witnesses report higher confidence levels for accurate decisions made for targets in later positions (7-9) when compared to earlier positions (1-3). However, these results suggest that there is no serial position effect, or lap effect within sequential lineups - thus meaning that police officers may not have to account for position as much as was first thought - however, it must be acknowledged that the current study does not fully support the results presented by past research.