Many crimes are prosecuted on the basis of eyewitness testimony. But how accurate are eyewitness accounts? The misinformation effect and source monitoring are two psychological principles that explain how sometimes witnesses can be mistaken.
How Accurate Are Eyewitnesses?
If you've ever watched a television show where detectives are trying to solve a crime, you know that a lot of their job centers around interviewing suspects and eyewitnesses. Many times, in real life and in television, a guilty verdict is given if an eyewitness testifies that they saw the accused. But how reliable are eyewitness accounts?
Many studies have been done that have shown that eyewitness accounts are not always accurate. There are many reasons why this is true, but the one that intrigues social psychologists the most is when eyewitnesses believe that they remember what they saw but are wrong. Why would someone remember seeing someone driving a car involved in a hit-and-run, for example, even though that person is somewhere on the opposite side of town?
Psychologists have studied this phenomenon and why it sometimes occurs. There are two things that can make eyewitness testimony unreliable: the misinformation effect and source monitoring.
Loftus and the Misinformation Effect
The misinformation effect happens when an eyewitness is given misleading information that changes their memories of an event.
Elizabeth Loftus ran a famous experiment to demonstrate this phenomenon. In Loftus' experiment, subjects were shown a series of slides leading up to a car accident. Some people were shown one of a car stopped at a stop sign, and others were shown the car stopped at a yield sign.
Afterward, the researchers questioned the participants about what they saw. Some of the subjects were asked misleading questions, such as asking someone who had seen the stop sign whether they noticed the car stopping at the yield sign. Finally, after questioning, the participants were asked to pick out the slides that they had seen.
The results may surprise you: about 75% of the people not given a misleading question correctly identified the picture they had seen, but only about 41% of those given misinformation could identify the correct photo. Most of them 'remembered' seeing the sign they were asked about, but not the one they actually saw.
What does this mean in the real world? As police and lawyers question eyewitnesses, they can (even without meaning to) change the memory of the eyewitnesses, resulting in faulty statements.
Source Monitoring and Eyewitness Accounts
Besides the misinformation effect, another problem with eyewitness statements involves source monitoring, or the process of remembering where you heard or saw something.
Have you ever seen someone at a party or in class and not been able to place where you knew them from? This happens all the time with people: they see someone who is familiar to them but can't quite place the person. This is a common example of a source monitoring problem.
What does this have to do with eyewitness testimony? An eyewitness might not be positive whether the guy they've picked out of a lineup is familiar because he was the culprit or because they saw him in the paper. He might even be familiar because he looks like someone they know! And the more stressful a situation is, the more likely people will experience source monitoring issues when trying to remember later.
No one knows exactly how common it is, but witnesses identifying a suspect from a lineup can experience source monitoring issues.
Eyewitness testimony is an important part of the U.S. legal system, and juries often convict suspects based on what witnesses say on the stand. Social psychologists have studied several problems with eyewitness testimony, particularly issues surrounding the misinformation effect and source monitoring.
Completing this lesson should enable you to describe and give examples of the misinformation effect and source monitoring issues.