Estimating the reliability of eyewitness identifications from police lineups

Abstract

Laboratory-based mock crime studies have often been interpreted to mean that ( i) eyewitness confidence in an identification made from a lineup is a weak indicator of accuracy and ( ii) sequential lineups are diagnostically superior to traditional simultaneous lineups. Largely as a result, juries are increasingly encouraged to disregard eyewitness confidence, and up to 30% of law enforcement agencies in the United States have adopted the sequential procedure. We conducted a field study of actual eyewitnesses who were assigned to simultaneous or sequential photo lineups in the Houston Police Department over a 1-y period. Identifications were made using a three-point confidence scale, and a signal detection model was used to analyze and interpret the results. Our findings suggest that ( i) confidence in an eyewitness identification from a fair lineup is a highly reliable indicator of accuracy and ( ii) if there is any difference in diagnostic accuracy between the two lineup formats, it likely favors the simultaneous procedure.