The Limits of Memory for Witnesses of Crime
Using so much brainpower to make quick decisions during a crime keeps us from creating lasting memories.
Armed robbery. Bank hold-ups. Sleight-of-hand shoplifting. While not all of these crimes are violent, what they all have in common is the sudden, stressful position they can often put eyewitnesses and victims in—namely, the need to quickly assess a situation and react in just the right way. Does this robber really have a gun in her pocket? When the suspected shoplifter vehemently denies it, when is it time to search his bag?
Our brains seek out, collect, and analyze countless cues in any given interaction, which all add up and tell us—consciously or no—who is lying, who is dangerous, and what action we should take. This almost-instantaneous set of calculations can save our lives in a crisis. But the side-effect of it is, it also takes up a lot of brainpower in that moment—brainpower that would otherwise be used to, for instance, create memories. That’s what new research into the psychology of memory has found, as published in the journal Memory.
“I don’t know if there’s any easy way to fix this problem, but at least police investigators can take it into account when interviewing witnesses.”
Kerri Pickel, a professor of psychology at Ball State University in Indiana, led the study, which involved videos with actors portraying, for instance, accused shoplifters who are denying wrongdoing. Some respondents in the study were told to simply watch the videos; others were tasked with trying to determine whether the people in the videos were lying or telling the truth.
“Compared to those who simply watched the video, those who judged the suspect’s veracity remembered her appearance less accurately,” Pickel recently told the Greensburg Daily News. “We also discovered that inducing witnesses to be suspicious of the suspect exaggerated the memory impairment effect, probably because it encourages witnesses to devote even more attention to the veracity judgment task.”
This was a limited study contained in an artificial environment, but presumably, the increased mental strain of having to make similar judgments about a suspect in person, and quickly, would impair one’s memory even more. And when eyewitnesses remember incorrectly—or when they are unduly influenced by investigators to remember differently, which is a whole separate problem—the consequences are substantial. According to the Innocence Project, misidentification by an eyewitness is the leading cause of wrongful convictions; it has been a factor in 72 percent of the (over 300) U.S. cases that have been later overturned with the help of DNA evidence. The Innocence Project website explains, somewhat poetically:
Research shows that the human mind is not like a tape recorder; we neither record events exactly as we see them, nor recall them like a tape that has been rewound. Instead, witness memory is like any other evidence at a crime scene; it must be preserved carefully and retrieved methodically, or it can be contaminated.
Pickel concurred that law enforcement tended to put too much weight on eyewitness testimony, considering how fallible it can be. “I don’t know if there’s any easy way to fix this problem, but at least police investigators can take it into account when interviewing witnesses.” To take that point one step further, the legal system should try to take it into account as well.