Work by experimental psychologists may forever change the way police gather eyewitness testimony--and help to prevent the wrong person from being indicted for a crime.

Monitor staff

A witness to a crime looks intently at a police line-up of people, and says, "Yes, number five. That's the person who did it."

And that's practically the end of the story. Case closed. If the witness can pick the person out of a line-up, police have their perpetrator. At least on television shows.

But late last year, in light of questions raised about the reliability of such evidence, the U.S. Department of Justice (DOJ) published the first-ever national guidelines on gathering such testimony in an attempt to make the process more scientific.

Psychologist Gary L. Wells, PhD, who was on the panel that wrote those guidelines, believes that rarely, if ever, has experimental psychology had such a definitive impact on national policy.

"The benefit for innocent suspects is immense," says Wells, professor of psychology at Iowa State University, "and it could be argued that this is one of psychology's greatest research-to-action achievements."

A flash of light

Research psychologists have been studying the reliability of eyewitness testimony for about 20 years. Their experiments have included having people watch videos of enacted crimes or staging mock crimes and asking them to identify perpetrators from photos, testing various interviewing techniques with eyewitnesses and with police interrogators, and exploring whether eyewitness accounts could be misled by questions after the event.

Early on, they found that eyewitness identification often was not very good. Studies showed that witnesses often identified the wrong person from the photos (in one study, almost half the time) and that police interviewing techniques often hampered information gathering.

At the same time, researchers found that they could improve eyewitness information by changing the way it is gathered. The researchers built, in the psychological literature, a strong case for better police practices and they testified on the reliability of eyewitness testimony in court cases.

But by and large, police departments haven't exactly knocked their doors down to find out what law enforcement was doing wrong in getting testimony to convict people.

Further, the justice system rarely gave police incentives to explore better methods, says Wells. "Courts almost never suppress identification evidence, even when the most egregiously biased line-up procedures are used."

But then came the 1990s and the widespread use of DNA testing. In cases across the country, the technique found that mistakes had been made. People had gone to prison for years for crimes that they did not commit.

Today, more than 60 people have been exonerated by DNA evidence. And most were convicted with eyewitness testimony.

Janet Reno steps in

In 1996, Gary Wells flew to Washington, D.C., at the request of DOJ staff for discussions related to his research. He was surprised to find he would be meeting with Attorney General Janet Reno. A prosecutor for most of her career, Reno had grown concerned about what the exonerations implied about eyewitness testimony. She had read articles by Wells in the American Psychologist and elsewhere and wanted to talk about his findings.

Soon after, she mandated that a national technical panel be brought together to recommend "best practices" for investigations involving eyewitnesses. The DOJ invited Wells to sit on that panel and permitted him to bring in five other psychological researchers.

Wells notes many of the researchers found the turn of events hopeful, yet "odd." They generally believed, he says, that the "experimental literature in psychology had already made a stronger and more informative case for reform than any collection of case studies [such as the DNA exonerations] could possibly muster."

But at least the exonerations had brought pressure on the system to undertake that reform.

Panel does its work

Over the next year-and-a-half, DOJ's panel of 34 people from four professions fought it out. Researchers, prosecutors, defense attorneys and law enforcement officials, in meeting after meeting and over drinks afterward, discussed and argued.

Wells says the researchers found--much to their astonishment--that "they were in the driver's seat." They had done the only research on the topic and that research gave the talks their foundation. The panel's reading material consisted of the psychological studies.

On the other hand, says Wells, he was pleasantly surprised by the police officers' reactions. The officers' own brand of research indicated something needed to be done: They had been there when a witness emphatically declared "Number Four" in a line up to be the perpetrator, when "Number Four" was a fellow police officer being used as filler.

It was the prosecutors who were more often at loggerheads with the researchers, out of fear that police failures to meet overly demanding guidelines would cast shadows over the prosecutions' cases.

Through the battles, says the DOJ project director Richard Rau, PhD, the police often served as the final arbiters. And, in October, DOJ published the guidelines.

DOJ acknowledges psychological research's primary impact on the guidelines. Reno, in her message about the impetus for the work, cites the "growing body of research in the field of eyewitness identification."

The guidelines' introduction states, "During the past 20 years, research psychologists have produced a substantial body of findings regarding eyewitness evidence," that offers the legal system a "valuable body of empirical evidence."

The 38 pages of recommendations call for, for example:

  • Interviewing a witness with open-ended questions and avoiding questions that would lead the witness. Researchers have found that open-ended questions can elicit much more information, but police tend to ask few open-ended questions and to interrupt witnesses who try to give narrative answers. On the other hand, studies have found that leading questions can change what the witnesses have to say.

  • Having only one suspect at a time be in a line-up and ensuring that "fillers" be people who fit the general description the witness has given. Researchers concluded that line-ups with more than one suspect increase the probability of a mistaken identification being taken seriously. And if fillers in a line-up don't look like the general description, the witness is likely to pick the suspect if he looks most like that description.

  • Telling the witness that the perpetrator may not be in the line-up. The research indicates witnesses sometimes feel it is their job to pick the person who looks most like the perpetrator.

    The panel's researchers, however lost a battle for a recommendation that line-ups be double-blind: Police officials resisted that addition, believing it would imply they couldn't be trusted.

    Psychological researchers also could not persuade the group that identification procedures should present the persons or the photos one by one, rather than in a group. Research shows that sequential presentation produces more reliable results.

    However, indicates Rau, after the guidelines have been used for a few years, the DOJ may undertake processes for improving and expanding them.

    In the meantime, Wells believes, the recommendations mark a sharp increase in the visibility and credibility of psychology within the legal system.

    They are, he believes, a "huge turning point" because, after this time, psychology will be much more integrated into criminal justice on questions of memory and the law. And, after all, he says, "Every witness on the stand is operating from memory."

    The guidelines are on the DOJ web site at Click on "What's New."

    The DOJ publication on exonerations, "Convicted by Juries, Exonerated by Science," is at in the abstracts database.

    Gary L. Wells presented his research at the recent APA/American Bar Association conference, "Psychological Expertise and Criminal Justice" in the session entitled, "Psychology, Law and Eyewitness Identification." Information on the conference course books and audiotapes (single or entire set) is available at (800) 374-2721, x5991.