The Human Factor: Eyewitness Testimony

Jan 21, 2013

Credit orangeacid / flickr

Eyewitness testimony is often highly regarded by juries and those who write television crime dramas.

Many people believe that their memory is infallible. Whatever they experience is recorded, frame by frame, like a movie, for later retrieval. Depending on one’s own personal history and past experiences, memories can in fact diverge significantly from the actual event.Anxiety, stress, and how questions are worded can conspire to create false memories.

One study involving a concept called weapon focus, went something like this: The researcher showed participants slides of a customer in a restaurant. Some participants saw a picture of a customer holding a gun. Others instead see the same customer, but they are holding a checkbook. When asked to identify pictures of the individual in a lineup, those that saw the picture of the gun were much less likely to correctly identify the man in the picture.

This demonstrates that people look at weapons instead of faces, confounding the accuracy of their memory for lineups involving an incident with weapons.

Another study showed a set of slides depicting a two-car accident in progress. Participants were either asked how fast the cars were going when they either smashed, or how fast they were going when they contacted. The participants were then asked to rate how fast the cars in the accident were going.

Surprisingly, the verb used changed the estimated rate of speed. The difference between smashed and contacted was a reduction of over 10 mph.

This research shows that memories can easily be distorted by the way questions are asked after a crime or incident, having severe implications for eye witness testimony.

Because our legal system so heavily relies on witness testimony, it is important that we all understand how fallible our memories can be. It’s easy to think that “my memory is better than the normal person,” but in reality, we are all liable to make these mistakes at some point in our lives.