A staged robbery. A roomful of witnesses. Yet few correct answers to the question,

Photo by: World Science Foundation

A staged robbery. A roomful of witnesses. Yet few correct answers to the question, “Whodunnit?”

“That’s the guy!”

Practically every courtroom drama has this scene: The tearful eyewitness pointing out the criminal at the defense table, or picking out a hardened perp from a lineup. But in reality, eyewitnesses are actually not all that great at picking out the person from a scene of a crime—and the result is often a tragic miscarriage of justice.

Skeptical? Below is a visceral demonstration of just how bad people are at identifying criminals right under their noses. At a recent World Science Festival event, “The Science of Justice: A Matter of Opinion,” we staged a theft onstage midway through the panel, then presented the audience with a photo lineup of suspects at the end of the talk. You can see how well they did at identifying a brazen thief who had appeared right in front of them in a well-lit room just an hour or so earlier:

83 percent picked the wrong man—and the most popular choice by far was one of the five innocent suspects! What’s more, this was a mostly white audience faced with a lineup of six white suspects; witnesses tend to perform even worse when asked to distinguish between individuals of a different race than their own. And yet eyewitness testimony remains one of the most powerful tools that a prosecutor can use to sway judge and jury.

Faulty eyewitness identifications are one of the leading causes of wrongful convictions. According to the Innocence Project, of the 317 people in the U.S. exonerated by DNA evidence after conviction, 73 percent were put away by a mistaken eyewitness ID. And at least 40 percent of those cases involved a cross-racial identification.

It isn’t that eyewitnesses are maliciously maligning innocent people; often they’re just trying to help solve a case. They might pick the guy in a lineup that looks most like the perp, even if they’re not sure, because they feel that they have to pick someone. Police officers contribute to the problem in a variety of ways: they may subtly or unconsciously indicate who the suspect is in a lineup, or reinforce a shaky ID by telling the witness that the suspect is a “bad guy.”

There are a number of ways that the justice system could ensure that eyewitness testimony doesn’t put away innocent people and let the real criminals go free. Police departments could ensure that the officers administering a lineup do not know who the primary suspect is; they should also tell witnesses that the perpetrator may not be in the lineup at all, and ask them to rate their level of confidence in their identification.

The Innocence Project also recommends that jurisdictions show the people in a lineup sequentially (one at a time), rather than all at once; research shows this reduces the likelihood of an incorrect identification. A few states and cities have already adopted some of these procedures—but across most of the country, justice is still in the eye of the beholder far too often.