Sleep Has No Effect on Eyewitness Identification Accuracy: Study
Thu, April 22, 2021

Sleep Has No Effect on Eyewitness Identification Accuracy: Study

Eyewitness testimony is critically important to the world’s justice system. Although it is not the most convincing form of evidence, it helps reconstruct facts and secure convictions / Photo by: sirtravelalot via Shutterstock

 

Eyewitness testimony is critically important to the world’s justice system. Although it is not the most convincing form of evidence, it helps reconstruct facts and secure convictions. To make it more reliable or to increase its accuracy, witnesses are often encouraged to think carefully and take their time in considering every possible suspect and scene they can remember. 

A new study published in the peer-reviewed journal Royal Society Open Science shared that sleep does not help the memory of the eyewitness. Royal Holloway, University of London's Ph.D. student David Morgan and the team from the Universities of Bristol, California, and Birmingham in the USA explained that sleep has always been involved in strengthening a person’s memory. However, there is a little study on how sleep affects an eyewitness’ memory such that they can accurately determine who the innocent or guilty suspects are.

 

Experimental Eyewitness and Control Group

Morgan and colleagues conducted a large-scale experiment on 4,000 online participants to measure the effect of sleep on identification accuracy. During the test, 2,000 of the participants watched a video clip of a mock crime. Some of them slept overnight while the others stayed awake during the day before the eyewitness test was done 12 hours after the exposure.  The other 2,000 became part of the control group that was immediately tested after they watched the video.

The researchers said that although the ability of the control group was better than the experimental group when it comes to determining who were the guilty and innocent suspects, the experimental groups were also “as reliable.”

Senior author professor Laura Mickes from the School of Psychological Science explained that their team predicated that sleep would improve the memory of an eyewitness. Surprisingly, the result showed that there was “no difference” in the memory ability of the wake and sleep groups in the experimental eyewitnesses batch.

Sleep Does Not Impact Identification and Reliability of Testimony

The group added that the reliability of the eyewitness statement was also not impacted by the short or long memory retention intervals. Their suggestion is for police to collect “expressions of confidence” at the beginning of the identification process because these can serve as predictive of statement accuracy regardless of whether there was a delay or not or if sleep occurred before asking the eyewitness.

They encouraged the Crown Prosecution Service (CPS), a public agency that conducts criminal prosecutions in England and Wales, to make use of their findings in their legal proceedings as well. The researchers shared that they are planning to conduct a large-scale replication of their memory experiment.

Some science-backed methods to improve a person’s memory includes meditation that does wonders to working memory, eating berries for better long-term memory, chewing gum while learning new things to make stronger memories, and exercise to enhance memory recall. Fitness in older adults has been proven to slow the memory decline without continued regular exercise. 

The group added that the reliability of the eyewitness statement was also not impacted by the short or long memory retention intervals / Photo by: Photographee.eu via Shutterstock

 

Eyewitness Misidentification: Facts and Statistics

The New England Innocence Project, an independent organization doing innocence work and was established to identify and exonerate wrongfully convicted individuals in New England, shared that eyewitness misidentification contributed to about 71% of the more than 300 wrongful convictions in the US alone. These wrongful convictions were overturned later on by post-conviction DNA evidence. It was in 1989 when the first DNA exoneration took place.

Out of the 130 DNA exonerees that the Innocence Project recorded in 2018, 40 of them or 31% of the cases involved eyewitness misidentification and 81 exonerees or 62% involved false confessions.

The organization believed that human memory does not operate like a videotape and its selective, dynamic, and constructive process of recalling a scene could be influenced by several factors. Studies have even recommended eyewitness testimonies to be served only as “trace evidence.” This means that investigators still have to use care in gathering other evidence to maintain the reliability and integrity of the process as well as lessen the chance of eyewitness misidentification.

Eyewitness identification experts recommend the administration of these procedures: complete description (of the suspect), blind administration, which means that officers should not know the photo array or lineup of the suspect, use of standard instructions, sequential presentation, and level of certainty. By sequential presentation, it means that people in the photo arrays and lineups should be presented to the eyewitness not in a simultaneous way but sequentially.

Jonah Lehrer of American magazine Wired previously wrote that “the biggest lie of human memory is that it feels true.” Perjury may be a crime but the majority of the eyewitness misidentification and errors are done unintentionally and unconsciously. They are just one side of the human remembering process. Neuroscientists have also documented how these memory recall mistakes occur. They said that as people summon the memory to surface in the present may change the memory itself.

Induced stress, memory decay, and poor eyesight are also some of the factors that play an influence in false testimony, although it applies only to a small percentage of eyewitness statements.