Eyewitness Memory

People tend to trust the testimonies of eyewitness, or people who were present at an event under question. According to psychology, this is wrong for many, many reasons.

Bad Observations
Our observations about the world are passive, and are thus a lot less accurate than we think they are. A study by Simon and Levin (1998) involved a person changing clothes in the middle of a conversation with an unsuspecting passerby, and the passerby didn't notice the majority of the time. Eyewitnesses don't expect an incident to occur and are often preoccupied with their own thoughts. If you were to witness a car crash, it's highly unlikely that you'd be thinking, "gee, I'd better keep my eyes open in case a car crash is about to happen" at the time. Because nobody can exhibit Alastor Moody's constant vigilance, this leads to inaccurate eyewitness memories.

We also generally remember only what we expect to see. Supporters of different sides of a sporting match will have opposing memories of the things that occurred during it. Our schemas of criminals and stuff affect the way we think about the world as well - in a vacuum, we'd be more likely to pick a guy in a lineup wearing something like a ski mask and black clothing as a robber.

Eyewitness Confidence
Some studies have also shown that eyewitness confidence has absolutely no effect on eyewitness memory. A study by Bradfield, Wells, & Olson (2002) showed that eyewitness confidence increases upon positive feedback that your decisions are correct, whether or not they actually are so.

Emotions
The perceived level of violence and levels of anxiety affect one's memory. For example, eyewitnesses are more likely to describe a person toting a gun with more accuracy and detail than one without, because if you see someone like that, your brain automatically goes, 'whoa, a gun, I've gotta pay attention or I'm gonna die'.

A meta-analysis by Deddenbacher, Bornstein, Penrod, and McGorty showed that heightened levels of stress and anxiety have a negative impact on identification accuracy and the ability to remember the details of a crime scene.

Related Studies
We have looked at many studies and case studies. Quite a few of these have to do with eyewitness memory, including:
 * Loftus & Palmer (1974)
 * Ronald Cotton
 * Yuille & Cutshall (1986)