CrimeExperts urge caution in relying upon eyewitness identifications in criminal cases

A new report from the National Research Council recommends best practices that law enforcement agencies and courts should follow to improve the likelihood that eyewitness identifications used in criminal cases will be accurate. Science has provided an increasingly clear picture of the inherent limits in human visual perception and memory that can lead to errors, as well as the ways unintentional cues during law enforcement processes can compromise eyewitness identifications, the report says.

“Human visual perception and memory are changeable, the ability to recognize individuals is imperfect, and policies governing law enforcement procedures are not standard — and any of these limitations can produce mistaken identifications with serious consequences,” said Thomas Albright, director of the Vision Center Laboratory at the Salk Institute for Biological Studies and co-chair of the committee that wrote the report. The report focuses on identifications of strangers rather than of family members or others well-known to the witness.

An NRC release reports that problems with eyewitness identifications have long been documented, and many of the cases in which DNA evidence later exonerated an innocent person involved at least one mistaken eyewitness. Research in recent decades has revealed many factors that can lead to such mistaken identifications, the report says. Conditions during the commission of the crime such as dim lighting, brief viewing times, stress, or the presence of a visually distracting element such as a gun or knife can influence people’s perceptions. Gaps in sensory input are filled by expectations that are based on an individual’s prior experiences with the world, which can bias perceptions. Studies also have shown that eyewitnesses are more likely to make mistakes when making an identification among people of another race rather than when making an identification of a person from the eyewitness’s own race.

In addition, memory is often an unfaithful record of what was perceived through sight; people’s memories are continuously evolving. As memories are processed, encoded, stored, and retrieved, many factors can compromise their fidelity to actual events. Although the individual may be unaware of it, memories are forgotten, reconstructed, updated, and distorted.