According to research, eyewitness identification testimony might be exceedingly unreliable. Although witnesses are frequently certain that their recollection is correct when identifying a suspect, the malleability of human memory and visual perception makes eyewitness testimony one of the most untrustworthy pieces of evidence. The study of eyewitness misidentification has led to the development of improved interrogation techniques for use by police investigators.
There have been many studies conducted on the reliability of eyewitness identification. These studies have shown that eyewitnesses often identify suspects without properly considering other possibilities. For example, witnesses may feel compelled to choose one option over another even if they know this not be true. This phenomenon is known as selection bias. Witnesses may also try to fit facts into their memory system rather than allowing the system to adjust itself which can lead to inaccurate recollections. Finally, the mere fact that we see someone do something wrong is not enough to guarantee that we will remember them as guilty later. Our brains need additional information such as a description of the clothing worn by the perpetrator or a photograph of him/her before we can accurately identify someone from just their face.
In summary, eyewitness identification testimony is highly unreliable and should be treated with caution by jurors.
Courts paid little attention to the issues surrounding eyewitness identification until DNA evidence was used to exonerate criminal defendants, in some cases decades after they were convicted. The work of legal scholars like Elizabeth Loftus has led judges to require police to read warnings to witnesses before they make an identification. These warnings explain that many people are mistaken when they first identify suspects and that later changes in memory can lead to inaccurate identifications.
There are several factors that can affect how well someone remembers events that happened earlier that day or even years ago. Memory works by storing information into different parts of the brain. Emotional events are stored primarily in the amygdala while logical events are stored in the hippocampus. Stress can cause these two areas of the brain to function differently, which could influence what people remember from a crime scene.
The police officers who investigate crimes must decide whether to charge someone with a crime based on their recollection of the event. If the witness is unable to help out with this investigation, there are also eyewitness officers who can interview people who were present at the scene of the crime. These officers should use caution not to ask leading questions that might influence the witness's response.
Judges often exclude eyewitness testimony because they believe it cannot be verified enough to justify sending a defendant to prison.
When adopting and evaluating eyewitness procedures, such as lineups, in criminal cases, law enforcement and the courts should follow the suggestions of social scientists. These researchers have shown that eyewitness evidence can be very inaccurate, especially when made close in time to the event.
Studies have shown that eyewitnesses often identify people who aren't guilty of any crime. Research has also shown that witnesses may pick out a person because he or she fits the description given by the victim or matches some other characteristic about which the witness harbors bias. For example, witnesses are more likely to identify black men as perpetrators if they have an unfair prejudice against black men. Also, witnesses may select a suspect because they feel sorry for him or her; this is called "moral judgment" and it can influence what people do even if they don't consciously think about it. Finally, studies have shown that the likelihood of an accurate identification decreases if the witness sees the perpetrator again after the incident.
In addition to these factors that can lead to false positives, there are other reasons why eyewitnesses might incorrectly identify someone. For example, witnesses may confuse each other's faces or give incorrect descriptions. Witnesses may also change their initial impressions of a defendant to fit evidence they later learn.