An eyewitness may seem like an invaluable resource for a prosecutor to prove their case. Eyewitness testimony has long been viewed as highly reliable evidence. However, advancements in forensic DNA testing in recent years have shed light on how frequently eyewitnesses actually get it wrong.
In fact, DNA testing has led to overturned convictions in 70% of cases involving eyewitness testimony. In other words, the DNA evidence proved that eyewitnesses misidentified the perpetrator seven out of 10 times. How could an organ as complex as the brain be so prone to error?
The fallibility of memory
According to a recent report, there are a few different factors that can affect one’s memory of an event:
- Accuracy: Situational conditions can make it more difficult for a witness to discern details. For instance, definitively recognizing a person standing on the other side of a dimly lit room would be challenging.
- Focus: The human brain can’t focus on multiple things at once. In a dangerous situation where you perceive your life to be at risk, you are more likely to focus your attention on the item that poses the greatest threat (e.g., the weapon) rather than on the facial characteristics of the person holding it.
- Conflation: The brain has a tendency to receive input and convert it into a memory that’s more concrete. For instance, if you hear someone shout, “he’s got a gun!”, then your brain may create a memory of you seeing the perpetrator holding a gun – even if you didn’t actually see it.
In any given situation, your conscious brain can only absorb a small fraction of the details in it. However, since storing incomplete memory fragments would be of little use to us, the brain gets creative to help us out. It absorbs partial information from a scene or event and then reconstructs a complete event for us – to create a complete memory that makes sense to us. It’s important to understand, then, that many of the details in our memories are created from inference – and not from fact.
The more you recount, the more you lose
In school, we’ve always been taught that repetition helps to cement new information into our brain. However, according to the report, when an eyewitness is asked to provide repeated accounts of an event, their memory of it becomes increasingly likely to change or be lost. However, they may not realize that their story has changed, because their brain continues to work subconsciously to create a complete picture of what happened – even if the memory is only fragmented.
Prior to ever testifying in court, an eyewitness will often recount their memory of an incident many times – in police interviews and meetings with lawyers. Thus, when an eyewitness takes the stand in court, their testimony may be an altered version of the actual events. However, since they’ve had so many opportunities to retell the events by then, they may be more confident about what they say. And a confident eyewitness has the power to sway a jury.
Facing criminal charges can be a scary thing – especially if there’s a witness testifying against you. It’s important to work with a criminal defence lawyer who can convincingly debunk the reliability of such testimony.