(Medical Xpress)—Trying to determine if a suspect is lying hurts the witness' ability to remember details accurately, says new research from Ball State University.
"Judging Veracity Impairs Eyewitnesses' Memory of a Perpetrator " analyzed responses from about 300 people and found most were less accurate about recalling details if they had to consider if a perpetrator was lying or telling the truth. The research was recently published by the journal Memory.
"For this study, we used actors to create videos of individuals delivering brief spoken messages," said lead author Kerri Pickel, a psychological science professor. "For example, in one experiment the actor portrays a woman accused of being a shoplifter's accomplice. In the video, she talks about what she was doing in the store and denies having anything to do with the shoplifting."
She said most humans are wired to believe what others say, so focusing on visual or verbal clues causes errors in recall.
"Our research participants watched the video and later tried to remember her appearance. Compared to those who simply watched the video, those who judged the suspect's veracity remembered her appearance less accurately. 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."
Pickel believes legal investigators place too much emphasis on eyewitness testimony.
"There are numerous situations in which eyewitnesses might want to figure out whether a suspect or perpetrator is lying," she said. "A bank robber might claim to have a gun hidden inside his jacket, or suspects might make statements about their identity or intentions that could be true or false. What we found is that the act of trying to determine whether an individual is being deceptive hurts the witness's ability to remember that individual accurately.
"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. DNA testing has proven that sometimes people are imprisoned for crimes they didn't commit. Mistaken eyewitness evidence is the major cause of wrongful convictions, so we need to find ways to improve eyewitness reports and to use them wisely."
The video project is part of the mission of the Legal/Trauma Research Center, co-founded by Pickel to conduct research and offer consultation on issues like victimization, bullying, eyewitness accuracy and legal decisions.
Her next project is a study showing that judging veracity not only causes witnesses to remember suspects less accurately, but ironically, it also makes them more confident about their memory. The preliminary indication finds that if people feel strongly motivated to do their best in deciding whether the suspect is lying, their memory performance gets even worse.