Eyewitness testimony

Reliability

The reliability of eyewitness testimony has been questioned by psychologists since the beginning of the 20th century.[1] However, many early studies on the matter were regarded as insufficient.

This questioning of its credibility began with Hugo Munsterberg, who first developed the field of Forensic Psychology. He specifically doubted the reliability of perception and memory in “On the Witness Stand.” Interrogation was mentioned as an issue because of its intimidating methods. Through this he developed an early version of the lie detector. There was a torn reaction to his ideas; while the legal arena was in stern disagreement, it was popular among the public.[2] It was not until forensic DNA testing began exonerating innocent people d 52 of the first 62 DNA exoneration cases involved eyewitness testimony.[3] The Innocence Project reports eyewitness misidentification occurs in approximately 75% of convictions that are overturned.[4]

In the USA, juries are responsible for assessing the credibility of witness testimony presented in a trial.[5] Research has shown that mock juries are often unable to distinguish between a false and accurate eyewitness testimony. The confidence level of the witness is often seen by jurors to correlate with the accuracy of their testimony. An overview of this research by Laub and Bornstein shows this to be an inaccurate gauge of accuracy.[6]

Another reason why eyewitness testimony may be faulty is due to an eye witness’s memory being influenced by things that they might hear or see after the crime occurred. This distortion is known as the post-event misinformation effect (Loftus and Palmer, 1974). After a crime occurs and an eyewitness comes forward, law enforcement tries to gather as much information as they can to avoid the influence that may come from the environment, such as the media. Many times when the crime is surrounded by much publicity, an eyewitness may experience source misattribution. Source misattribution is when a witness is incorrect about where or when they have the memory from. If a witness cannot correctly identify the source of their retrieved memory, the witness is seen as not reliable.

While some witnesses do see the entirety of a crime happen in front of them, there are some that only witness part of a crime. These witnesses are more likely to experience confirmation bias. Witness expectations are to blame for the distortion that may come from confirmation bias. For example, Lindholm and Christianson (1998)found that witnesses of a mock crime, who did not witness the whole crime, nevertheless testified to what they expect would have happened. These expectations are normally similar across individuals due to the details of the environment.