How is eyewitness testimony fallible?

Facing criminal charges is serious and if there are eyewitnesses that claim you committed the crime, you may be worried. The reality is that an eyewitness statement does not necessarily mean that a person committed the crime. 

According to the Association for Psychological Science, eyewitness testimony is not always reliable. 

Why do eyewitnesses seem trustworthy?

Eyewitnesses can be reliable, but the reliability is not as infallible as people may think. Most people believe in eyewitness testimony because they trust their own experience. It is easy to empathize with a person accusing another of a crime that he or she witnessed. If it was a traumatic event, then it must be memorable too. The problem is that you can repress trauma memories. Some believe that hypnosis can reliably awaken trauma memories but that is not necessarily true. The confidence that an eyewitness has can be persuasive to those who listen. 

Why is memory less reliable?

Your brain is not a video camera. It does not record experiences frame by frame. Instead, your brain creates a story out of your memories. Often, memories are a mix of the truth and fiction that your mind creates. Your subconscious can distort your memory or you could have biases that you do not have awareness of. The problem with memory is that while it can be accurate, it can also be inaccurate. Generally, you need objective evidence to be able to tell the difference. 

When two people remember the same event, one may have biases that force them to remember different details than the other person. Two perceptions of the same event can be wildly different.