People who witness crimes are often asked to identify suspects in a lineup. Traditionally, police would present them with six people simultaneously, five of whom are fillers who are innocent but resemble the suspect. Photo arrays are more common these days than live lineups, and previous studies found that these work better if the pictures are presented in a sequence, rather than all at once. Almost a third of U.S. law enforcement agencies have since adopted this sequential procedure.
However, juries have been increasingly encouraged to disregard eyewitness confidence. Eyewitness misidentification has played a role in the majority of 333 wrongful convictions that have been overturned since 1989 by DNA evidence, and research using mock observers to simulated crimes have further challenged the accuracy of eyewitness confidence.
But now, according to findings published in Proceedings of the National Academy of Sciences this week, the accuracy of eyewitness identifications during police lineups increases when the witnesses are confident. "Most of the mistaken IDs were initially made with low confidence, not high confidence," UC San Diego’s John Wixted explains in a statement. "In other words, the witnesses appropriately signaled that their identifications were error-prone."
Wixted’s team examined the accuracy of 348 photo lineup identifications with actual eyewitnesses to crimes committed in Houston, Texas. These lineups – 187 simultaneous and 161 sequential – were presented by investigators in the Robbery Division of the Houston Police Department between January 22 and December 5, 2013. And the lineups were double-blind: The suspects were strangers to witnesses, and the investigators administering the lineups didn’t know the identify of the suspects either. The witnesses made their identifications using a three-point confidence scale: high, medium, or low.
Eyewitness confidence, the team found, appeared to be a strong, reliable indicator of accuracy when an identification is made from a fair police lineup. And surprisingly, simultaneous photo lineups were better than sequential ones.
Recent reforms in the legal system, the authors write, may need to be reevaluated. "Ignoring low confidence in the beginning is a grave error. The witness is telling you that there's a good chance they're making a mistake," Wixted says. "To protect the innocent, it is important to realize that an initial low-confidence ID is untrustworthy. On the other hand, when lineups are fair and administered neutrally, high confidence at the start can also be quite telling."