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Eyewitness testimony: how reliable is a memory?

You may think you have an excellent memory. If someone asked you to recount the events of a particular meeting or encounter, you may feel confident in the accuracy of the details you provide. It’s natural for humans to be overly reliant on memory as evidence of truth. However, science shows us why memory may not always be the best thing to trust.

Why memory can let us down

A recent report explains some of the core reasons that memory is inherently unreliable:

  • Environment: Many environmental factors – such as distance, lighting and smoke – can impede your ability to clearly see someone well enough to correctly identify them later.
  • Attention: During a highly stressful situation – such as being mugged – you might expect to be in a state of heightened awareness. However, your attention can’t go in every direction at once. In a life-or-death situation, you’d be more likely to focus on the thing that could cause you harm (e.g., a weapon) rather than the personal traits of the individual aiming it at you.
  • Blurred lines: Humans can’t focus on multiple things at once, so you can’t absorb every detail of a given situation. Instead, you focus in on particular elements of a situation. Your brain then uses different senses to reasonably infer the missing details – and pieces them all together as one complete memory. Therefore, you may actually have a memory of seeing a man holding a knife, when in reality you simply heard someone in a crowded room yell, “he’s got a knife!”

Implications on eyewitness testimony

Eyewitness testimony often carries significant leverage in court. A convincing eyewitness can have a strong influence on a jury. However, eyewitness testimony has been proven unreliable. Forensic testing of DNA evidence has overturned a whopping 70% of convictions where eyewitness accounts were used.

Understanding the scientific inaccuracy of eyewitness testimony can be advantageous. A skilled criminal defence lawyer will know how to use such findings to discredit testimony against you – and help you move on with your life.