Interesting article, from 2000:
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.
Suddenly, a big impact on criminal justice
another, from 2006:
Mistaken or flawed identification has assumed a newfound prominence in recent years: It's been cited as a factor in nearly 78 percent of the nation's first 130 convictions later overturned by DNA testing, according to the New York-based Innocence Project, which works to free the wrongly convicted. As a result, a number of researchers are turning their attention to helping police departments and juries better understand the circumstances under which eyewitnesses observe crimes and later identify a suspect.
Since the publication of both the
American Psychologist and Department of Justice pieces, states such as New Jersey, North Carolina and Wisconsin have incorporated many of the recommendations, including one in the Department of Justice report that advises law enforcement officials to warn eyewitnesses that the culprit's appearance may have changed since the crime.
However, Wells challenges that recommendation in an upcoming article in
Law and Human Behavior. In the study, he presented participants with a video of a crime involving four culprits. Then, he asked the participants to identify the culprits from four six-person arrays that either included or did not include a culprit. He found that the instruction actually increased the participants' number of misidentifications.
"The instruction seems to loosen the criterion of eyewitnesses and increases their propensity to identify someone," he says. "Eyewitnesses start to imagine possible changes and think, 'This must be him.'"
How reliable is eyewitness testimony?