01/16/2015 11:34 am ET Updated Jan 16, 2015

This Simple Psychological Trick Could Vastly Improve Witness Testimony


You're at the grocery store, struggling to remember that final item you were supposed to buy. Taking a moment to close your eyes, your brain can focus on the task at hand. Chances are, you might remember those oranges you need to buy.

We know that eye closure can help jog memories, but not all scenarios make it socially comfortable: Imagine you're at a cocktail party, introducing guests whose names you've forgotten with your eyes closed.

Somewhat more gravely, what if you were at a police station, trying to recount the scene of a crime to detectives? Would you feel uncomfortable closing your eyes in an unfamiliar environment, for perhaps an extended amount of time? Would that discomfort affect the quality of your memories?

Psychology researcher Robert A. Nash of Aston University in the U.K. regularly teaches his student about the eye closure effect -- a simple way to boost memory recollection by shutting out unnecessary visual stimulus.

"When I teach my students about the eye closure effect, they always tell me, 'I would hate closing my eyes in a police interview!'" wrote Nash in an email to The Huffington Post. "So how is it that eye closure helps people remember, even though people hate the idea of doing it?"

Improving eyewitness memory is literally a life-or-death research question within the context of the criminal justice system. The Innocence Project, an organization that overturns wrongful convictions with the help of DNA evidence, says that eyewitness misidentification is the "single greatest cause" of wrongful convictions nationwide. Misidentification played a role in 72 percent of convictions overturned by DNA testing, according to the organization.

Separate research shows that eyewitnesses give the most accurate and detailed information if they feel comfortable with interviewers (especially child eyewitnesses). So Nash wondered if combining the two techniques -- comfort with the interviewer and eye closure for memory recall -- would boost accurate memories even more.

"This puzzle was what led us to wonder whether the benefits of eye closure might be improved if the interviewer first takes the time to make a witness feel comfortable," Nash continued.

In a series of experiments that tested the effects of eye closure, building a rapport between witness and interviewer, and combining the two techniques, Nash showed that detectives can in fact slightly boost the positive memory effects of eye closure, but not as much as he thought it would. In fact, the overwhelming message behind Nash's experiments were that eye closure helped memory recall "irrespective of whether or not rapport was built," wrote Nash.

To test the combined effects of eye closure and rapport building, Nash conducted two experiments. In the first, 66 study participants were randomly assigned to one of four conditions:

1. Recounting memories with eyes closed, to a sympathetic interviewer.
2. Recounting memories with eyes open, to a sympathetic interviewer.
3. Recounting memories with eyes closed, to a non-sympathetic interviewer.
4. Recounting memories with eyes closed, to a non-sympathetic interviewer.

Then they watched a six-minute silent film clip that showed an electrician entering a property, doing his job, but also stealing some items. Then, according to which groups they were assigned, the participants were either questioned about the film by interviewers who were instructed to "build rapport" with a friendly tone and personal questions, or interviewers that maintained a neutral tone with no follow-up personal questions.

He found that the people who closed their eyes and the people who were interviewed by a sympathetic interrogator had given the most correct responses about the short crime film they had watched, but statistical analyses showed that the two techniques were not necessarily dependent on each other. In other words, wrote Nash in the study, there was little evidence that building rapport "moderates the effectiveness" of the eye closure technique. Participants who had closed their eyes to remember details also had less "I don't know" responses during their interviews.

A second experiment with 112 study participants replicated the results of the first. After watching a video of an aggravated burglary, respondents were given the same set of conditions as before, though questions were broken into auditory details ("What was the victim's surname?") and visual ones ("What color was the door?"). Once again, closing one's eyes also led to fewer incorrect responses, as did a friendly rapport between interviewer and study participant. But rapport-building didn't seem to have much of an effect when it came to enhancing eye closure as a technique. It also didn't seem to matter whether the questions were about auditory or visual details.

Even though Nash wasn't able to show that rapport significantly enhanced the benefits of eye closure, the participants themselves did say that they were more comfortable with interviewers who had tried to establish a rapport with them -- something Nash called extremely important in potentially high-stress situations.

"That in itself is vital if we are to encourage witnesses to use [eye closure] during interviews," said Nash in a press release about his study.

However, Nash cautioned that the study participants couldn't exactly replicate the discomfort and even trauma of real eyewitnesses, who may also be victims of a crime.

"We still need to know much more about the various real-life contexts in which it would be beneficial and appropriate to ask a witness to close their eyes," Nash concluded.

In the future, Nash hopes to investigate whether or not simply explaining to an eyewitness that eye closure helps boost memory recall.

Nash's study was published online Jan. 15, in the journal Legal and Criminology Psychology.



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