More than 75,000 prosecutions every year are based entirely on the recollections of others, says the Wall Street Journal. While perjury is a felony, the overwhelming majority of eyewitness errors aren’t conscious or intentional. Rather, they’re the inevitable side effects of the remembering process. Neuroscientists have documented how mistakes happen. It turns out that the act of summoning the past to the surface actually changes the memory itself.
Neil Brewer, a psychologist at Flinders University in Australia, studied police lineups, in which witnesses are asked to pick out a suspect from a collection of similar looking individuals. He knew that strong memory traces are easier to access than weak and mistaken ones, which is why he gave his witnesses only two seconds to make up their minds. He also asked them to estimate how confident they were about the suspects they identified, rather than insisting on a simple yes-no answer. He was able to get a large boost in accuracy, with improvements in eyewitness performance ranging from 21 percent to 66 percent. Even when subjects were quizzed a week later, those who were forced to choose quickly remained far more trustworthy. The larger lesson is that, when it comes to human memory, more deliberation is often dangerous. We can talk ourselves into having a memory that doesn’t actually exist.