When a victim or witness of a crime is asked to identify the perpetrator, it makes a difference how certain they are at the initial identification, according to a new study led by a memory expert at the University of California, San Diego.
The American justice system should take note of eyewitness confidence, but only at the time of the initial identification and not at a later date in court. The findings also show that the traditional lineup procedure — one that presents suspects at the same time as known innocents — is more accurate in identifying the criminal than showing each suspect individually.
The researchers analyzed data from a field experiment conducted by the Houston Police Department in 2013. It includes 348 photo lineups in which police investigators who were blind to the identity of the suspect presented eyewitnesses with photos of the suspect along with five innocent “filler” subjects, either simultaneously or sequentially. The eyewitnesses were all strangers to the suspect.
The detectives also recorded eyewitness confidence at the time of identification, using a three-point scale of high, medium, or low confidence. The researchers believe this is the first field experiment to include initial confidence ratings.
The researchers find that traditional simultaneous lineups are, if anything, superior to sequential lineups and that witness confidence is a strong indicator of the accuracy of identifications. If at the time of police photo lineup a witness is confident about a memory, it is likely to be correct, but if they are not confident about a memory, it is much more likely to be incorrect.
It is well-documented that memory is malleable and that witnesses are suggestible. By the time eyewitnesses testify in court, it could be months or years after a crime has taken place. The confidence they expressed in their initial identification of a suspect can become unintentionally inflated.
Often, jurors only hear that dangerously inflated expression of confidence. In response, recent changes in jury instructions urge jurors to disregard eyewitness confidence.
“A blanket indictment of the reliability of eyewitness expressions of confidence is wrong,” said senior author Dr. John Wixted, professor of psychology in the University of California San Diego Division of Social Sciences and an expert in memory.
“It’s a huge mistake our legal system is making. At the time that they’re first making an ID, eyewitnesses can give us reliable information about their accuracy.”
According to the Innocence Project, as the researchers point out in their paper, eyewitness misidentification is the single greatest cause of wrongful convictions in the U.S., having played a role in more than 70 percent of the 330 wrongful convictions that have been overturned by DNA evidence since 1989.
“These facts are widely understood to mean that eyewitness memory is unreliable,” Wixted said, “but most of the mistaken IDs were initially made with low confidence, not high confidence. In other words, the witnesses appropriately signaled that their identifications were error-prone.”
“Ignoring low confidence in the beginning is a grave error. The witness is telling you that there’s a good chance they’re making a mistake.” Wixted said.
“To protect the innocent, it is important to realize that an initial low-confidence ID is untrustworthy. On the other hand, when lineups are fair and administered neutrally, high confidence at the start can also be quite telling. Judges and juries should pay attention to both. Doing otherwise is a disservice to justice generally and to protection of innocents especially.”
The study is published in the journal Proceedings of the National Academy of Sciences.