Why eyewitness testimony is bad

Importantly, these errors, once made, can be very hard to unmake. Some small memory errors are commonplace, and you have no doubt experienced many of them. You set down your keys without paying attention, and then cannot find them later when you go to look for them. Other sorts of memory biases are more complicated and longer lasting. For example, it turns out that our expectations and beliefs about how the world works can have huge influences on our memories.

The result of this lack of attention, however, is that one is likely to remember schema-consistent information such as tables , and to remember them in a rather generic way, whether or not they were actually present. But some experimental psychologists believed that the memories were instead likely to be false—created in therapy. The student subjects were told that the researchers had talked to their family members and learned about four different events from their childhoods.

The researchers asked if the now undergraduate students remembered each of these four events—introduced via short hints. The subjects were asked to write about each of the four events in a booklet and then were interviewed two separate times.

The trick was that one of the events came from the researchers rather than the family and the family had actually assured the researchers that this event had not happened to the subject. In the first such study, this researcher-introduced event was a story about being lost in a shopping mall and rescued by an older adult. For example, one group of researchers used a mock-advertising study, wherein subjects were asked to review fake advertisements for Disney vacations, to convince subjects that they had once met the character Bugs Bunny at Disneyland—an impossible false memory because Bugs is a Warner Brothers character Braun et al.

Another group of researchers photoshopped childhood photographs of their subjects into a hot air balloon picture and then asked the subjects to try to remember and describe their hot air balloon experience Wade et al. Other researchers gave subjects unmanipulated class photographs from their childhoods along with a fake story about a class prank, and thus enhanced the likelihood that subjects would falsely remember the prank Lindsay et al.

Using a false feedback manipulation, we have been able to persuade subjects to falsely remember having a variety of childhood experiences. In these studies, subjects are told falsely that a powerful computer system has analyzed questionnaires that they completed previously and has concluded that they had a particular experience years earlier.

Subjects apparently believe what the computer says about them and adjust their memories to match this new information. A variety of different false memories have been implanted in this way. To conclude, eyewitness testimony is very powerful and convincing to jurors, even though it is not particularly reliable.

Identification errors occur, and these errors can lead to people being falsely accused and even convicted. Likewise, eyewitness memory can be corrupted by leading questions, misinterpretations of events, conversations with co-witnesses, and their own expectations for what should have happened. People can even come to remember whole events that never occurred. The problems with memory in the legal system are real. But what can we do to start to fix them?

A number of specific recommendations have already been made, and many of these are in the process of being implemented e. Some of these recommendations are aimed at specific legal procedures, including when and how witnesses should be interviewed, and how lineups should be constructed and conducted.

Other recommendations call for appropriate education often in the form of expert witness testimony to be provided to jury members and others tasked with assessing eyewitness memory. Eyewitness testimony can be of great value to the legal system, but decades of research now argues that this testimony is often given far more weight than its accuracy justifies.

According to a new perspective published in PNAS , that shouldn't surprise us. The paper's author, Salk neuroscientist Thomas Albright, argues that we've learned a lot about how humans perceive the world, process information, and hold on to memories.

And a lot of it indicates that we shouldn't value eyewitness testimony as much as we do. Still, Albright offers some suggestions about how we can tailor the investigative process to compensate a bit for human limitations.

Albright has some history in this area, as he co-chaired a study group at the National Academies of Science on the topic. His new perspective is largely a summary of the report that resulted from the group, and it's an important reminder that we have sound, evidence-based recommendations for improving the criminal justice system. Failure to implement them several years after the report is problematic. According to the perspective, things go wrong for eyewitnesses right from the start.

While human vision is good, there are plenty of conditions—low lighting, distance, and sudden actions—that make it difficult to accurately perceive what's going on. And we don't always focus on the things that would make us a good eyewitness; if someone's waving a gun around, we tend to look at the gun, not their face. And even if they're not waving a gun, we may believe that they were if the visual information we recall is ambiguous, but we know there was a robbery happening.

Faced with partial information, research indicates that our brain's response isn't to commit what information we do have to memory. Instead, our brains attempt to create a coherent picture that makes sense. This often involves filling in details using past experience as a guide.

The resulting memory may be satisfyingly complete, but it can come at the cost of incorrect information. Memories are also remarkably malleable. Rather than remaining tucked away unchanged in our hippocampus, lots of research shows that the mere act of recalling something can allow its memory to be updated or, in some cases, lost.

One reported that he had identified Grant without doubt or hesitation. Three of the eyewitnesses reported that the detective told them that they had picked the same person other people had, though the detective himself denied having made such statements. The detective also admitted making a similar comment to at least one other witness.

As a result, witnesses who have received confirmatory feedback provide testimony that is highly persuasive to jurors. In one study, people playing the role of jurors were able to reliably distinguish between accurate and mistaken eyewitnesses when the witnesses had not received any confirmatory feedback. In other words, the confirmatory remark made the mistaken eyewitnesses just as persuasive as the accurate ones. The way to avoid these problems with eyewitness testimony is for police to adopt best practices based on the psychological research.

Confidence reported at trial after the eyewitness has received confirmatory feedback is not. Unfortunately for Lydell Grant, these reforms came a year too late.