Wixted and Mickes proposed a new measure called confidence-accuracy characteristic (CAC) analysis. CAC analysis6 aimed to answer the question that Wixted felt previous work had overlooked. And, they argued, this was what should really matter to jurors in court: if a witness identifies a suspect with a given level of confidence, how likely is that identification to be accurate? Using CAC analysis, data from previous lab studies now showed that highly confident witnesses were up to 97% accurate7. This was a seismic and controversial finding, says Thomas Albright, a neuroscientist at the Salk Institute for Biological Studies in La Jolla, California. Wixted “came into the field and turned it topsy-turvy”, he says. Accordingly, “there was a tremendous amount of pushback”, says Andrew Smith, a memory researcher at Iowa State University. Wixted says that critics were evenly split between the argument that eyewitness memory could never be reliable and others who said that the relationship between confidence and accuracy was already common knowledge. Real-world data supported Wixted’s arguments, too. He had collaborated with the Houston Police Department in Texas on a study examining nearly 350 photo line-ups8. The department had adopted procedures that created fair line-ups, such as double-blinding — making sure that the person administering the process didn’t know who the suspect was. Wixted also asked the Houston officers to record their eyewitnesses’ confidence immediately after the identification process. The study suggested that high-confidence identifications were roughly 97% correct, whereas low-confidence identifications were just a little better than a coin flip. Further support of the theory, says Wixted, is seen in an analysis of data from the Innocence Project, a non-profit organization in New York City that aims to clear the names of people who have been wrongly convicted. In 92 of the first 250 cases in which DNA evidence overturned a conviction9, trial testimony had a record of what the eyewitness said when their memory was first tested. In every case, the eyewitness was less confident during the first test than they were in court. In 2017, Wixted and Wells, who had in the past disagreed publicly about eyewitness memory, co-authored a paper10. It argued that confidence could be indicative of accuracy during the first test of a witness’s memory in a police line-up — but only under “pristine” testing conditions. These include steps such as double-blinding and careful line-up presentation to avoid drawing attention to the suspect. The paper had a huge impact, says Margaret Bull Kovera, a psychologist at the City University of New York in New York City. A survey last year of psychologists who have studied eyewitnesses reveals the turnaround: 89% agreed that, in pristine conditions, an eyewitness’s confidence is informative about accuracy11.
—"Memory on trial: the new science of when to trust eyewitness testimony" from Nature
