Science Helps Improve Eyewitness Testimony

you actually perceive a gun, even though there may not be one. The gun gets inserted into your perceptual experience because conditions lead to significant uncertainty, and the gun is what you expect under those kinds of conditions.”

In a related phenomenon, a person may unconsciously insert things into memory from an outside source. For example, a witness might perceive the events of a crime and store that information in memory, and then read in the newspaper that another witness said the perpetrator had a handgun. Even though the original witness didn’t perceive a handgun at the time of the events, that information may get implanted into her memory, without awareness that it didn’t come from her own experience.
“Contamination” of a witness’s memory may also happen in more subtle ways. For example, a police officer who is supervising as a witness picks a suspect out of a lineup may, without realizing it, offer nonverbal cues of affirmation, increasing the witness’s confidence in his identification.

Are most people aware of how error-prone vision and memory can be? “Generally, no,” Albright says. “As we go through the world, we accept what see without question. And so if somebody else tells us that they saw something, we grant them the same benefit of the doubt. But the truth is, if you look at it carefully, you find that individuals very commonly misperceive things. Juries in general, and probably most judges as well, don’t have a good understanding of that.”

To counter that lack of awareness, Identifying the Culprit recommends that courts bring in experts to advise juries about the ways that eyewitness evidence can fail. The report also urges the use of “double blind” lineups, where the police officer administering a lineup does not know who the suspect is — leaving them unable to offer biasing cues to an eyewitness. And it recommends that police officers record a witness’s confidence level upon first identifying a suspect — a time when their assessment of their own confidence is more likely to be accurate, and when their memory is less likely to have been contaminated. 

Impacts in the Justice System and Beyond
In the years since the National Academies’ report was released, at least 19 states have passed legislation or adopted rules requiring reforms recommended by the report, such as using double-blind lineup procedures and recording witnesses’ confidence levels. The federal government has acted as well; in 2017 the Department of Justice released new guidelines for how lineups using photographs should be conducted in federal criminal cases, based on procedures recommended in the report. And shortly before that, the International Association of Chiefs of Police issued a new model policy for conducting lineups, also drawing upon the report.

The report has also engaged more researchers to work on the problem of eyewitness identification. “In the scientific community, it’s been incredibly valuable,” says Albright. “There are basic scientists, who have an understanding of how visual perception and memory work, who are now using that information to help figure out better ways of doing lineups, for example.” 

One area of research that has great promise for improving eyewitness identification in the future is the use of modeling to estimate the accuracy of a witness, Albright says. Developed through testing, models could quantify and factor in characteristics that are known to affect perception — the lighting at the crime scene, for example, and the witness’s viewing distance — and offer a numerical estimate of how accurate eyewitness testimony is likely to be. A similar approach is already being used with success in medical diagnosis and prognosis, Albright says. “These are tried and true techniques in a discipline that has lots of parallels to the criminal justice problem, and they could similarly be applied to the criminal justice problem.” 

Has the report and its many impacts affected Albright personally? “I’ve done a lot of things in my scientific career, but there are few things that I’m as proud of as I am of this report. Not only is it an important societal problem, but our work is having an impact on the world in real time,” he says. “At some point I had this realization that there are a lot of things I know about the brain that are relevant to immediate problems in society, and this is one of them. And it’s having — within my lifetime — an effect on people’s lives.”