Unreliable eyewitness testimony: when memory plays tricks on us
The human memory isn’t like a tape recorder. It doesn’t record life events and play them back exactly as they happened. Instead, scientists have found that the brain reconstructs memories each time a person recalls them.
Because of this, memories can change a little bit each time they are remembered and reconstructed. For example, it can be difficult to tell the difference between our actual childhood memories and the way childhood stories were told to us by our families over the years.
In the case of eyewitness testimony in a criminal case, remembered and reconstructed memories are notoriously unreliable and dangerous. Still, juries tend to place great weight on witness testimony. According to the Innocence Project, witness testimony has been identified as the leading cause of wrongful convictions. It has the power to ruin lives.
How eyewitness memories change over time
We might imagine that a witness sees a crime occur and then recounts exactly what she saw. However, because memory does not act like a tape recorder, this isn’t the case. She reconstructs the memory each time she remembers what happened. She reconstructs the event when she tells the police. She reconstructs it again when she IDs a suspect in a police lineup. She reconstructs it yet again when she tells the prosecutor about the events and again when she tells the jury.
Each time, her act of reconstructing may subtly alter the way she remembers it. Over time, her story may change — often subtly combining with information provided by the police officers and attorneys who questioned her. It becomes a false memory.
Stress makes it worse
Witness testimony is especially prone to the false memory phenomena because the event that is being recalled was one that happened under stress. This is especially true when weapons were present at the crime because weapons are known to intensify stress and distract witnesses.
Other factors add to the confusion
Other factors have been shown to increase the likelihood of incorrect eyewitness testimony. These include a disguise worn by the alleged perpetrator, racial differences between the witness and the suspect (studies show that people are less able to identify a stranger’s face when they are of a difference race), and lack of distinctive characteristics like tattoos.
Some people are more likely to be in the wrong place at the wrong time
Some people are likely to have more interactions with police than others. Statistics show that people with chemical dependency issues or who have certain psychological disorders are at a high risk for criminal involvement, so they are more likely to be taken into custody. While in custody, they may be asked to stand in police lineups, or their photos may be shown to crime victims. This puts them at a higher risk for false identification by eyewitnesses.
So, what can we learned from all of this? Memory isn’t foolproof. Just because a witness identifies a suspect – just because she says that things happened one way – does not mean that they did. Witnesses get it wrong, even when they have the best intentions.
Our criminal justice system is designed to take this into account. That’s why people are innocent until proven guilty. Defense lawyers aggressively question all of the evidence presented in a criminal case. They look at the circumstances around a police lineup, how a witness’s testimony has changed over time or other factors so that a witness’s memories about what happened during a stressful event are never taken as fact.
Have you ever remembered something incorrectly? Has your memory ever played tricks on you?