Eyewitness Confidence and Decision Time Reflect Identification Accuracy in Actual Police Lineups

Abstract

Objective: Although there are many lab-based studies demonstrating the utility of confidence and decision time as indicators of eyewitness accuracy, there is almost no research on how well these variables function for lineups in the real world. In two experiments, we examined confidence and decision time associated with real lineups that had been conducted using research-based recommendations. Hypotheses: We expected that how confident an eyewitness sounded and how quickly that eyewitness made their identification would be associated with whether that eyewitness identified a suspect or a filler. We also hypothesized that people’s interpretations of eyewitness confidence could be easily influenced by additional, biasing information. Method: Using audio recordings of these lineups, we examined (a) participants’ subjective ratings of how confident an eyewitness sounded at the time of the identification and (b) objective data regarding how quickly the eyewitness made the identification decision. We also manipulated what additional information, if any, participants received in Experiment 2. Results: In both experiments, decision time and confidence predicted whether the eyewitnesses identified the suspect or a known-innocent filler, and when decision time and confidence diverged, it is likely that the eyewitness identified a filler. In Experiment 2, we found that people’s interpretations of eyewitness’s confidence statements could be biased. When observers believed that the witness picked a filler rather than a suspect, or vice versa, this changed how confident they thought the witness sounded. Conclusions: Confidence and decision time should both be collected when administering real lineups, but objective decision time data may be the most useful because people’s perceptions of confidence are easily altered.