The Biasing Influence of a Police Showup: Does the Observation of a Single Suspect Taint Later Identification?

Abstract

This experiment investigated whether a police showup or presentation of a single suspect to a witness has a biasing effect on later identification at a lineup. All of the subjects viewed a videotape of a simulated crime, ostensibly real and photographed by a surveillance camera. After a short delay, approximately half of the subjects were shown a single photograph of an innocent suspect and told that he had been apprehended by the police. Five to seven days later, all of the subjects, including those who had not observed the showup, viewed a photographic lineup of six people. The proportion of subjects choosing the innocent suspect from the lineup was significantly higher in the group who had viewed the showup than in the control group who had not observed it. Of those subjects who had observed the showup and made a choice from a subsequent lineup, approximately 40% identified the innocent suspect as the perpetrator. These results indicate that a showup procedure is a biasing method of identification.