Eyewitness Memory and Testimony: How Reliable Is It?

The reliability of a witness's memory should be studied in detail, as it's often the only source of information about a crime or event. This is precisely what eyewitness testimony is dedicated to.

Written and verified by the psychologist Loreto Martín Moya.

Last update: 20 October, 2022

In most crimes, the reconstruction of the events is made up of snippets of information from the people who were present. This means that eyewitness memory plays an essential role in the course of events. In fact, it’s often the only source of information available to the professionals investigating a case.

However, how reliable is eyewitness memory? Can the nature of the events change in their memory?

Do witnesses, like other human beings, make cognitive errors and become victims of their own biases? Is the idea of police officers being fair witnesses under any conditions true? We’ll try to answer these questions through the relevant field of study: the psychology of eyewitness testimony.

The two errors of eyewitness memory

Hugo Münsterberg (1863-1916) was a German-American psychologist. It was he who first introduced the term, eyewitness testimony. He questioned the reliability of the testimony of eyewitnesses to a crime.

Since the study of memory is an area of research in psychology, it was established that eyewitness memory would have to be determined by psychologists.

Eyewitness testimony is based on the two types of errors that are mostly observed in the memory of the witness. According to Santos, Hernangómez, and Taravillo (2018), these errors are:

• Errors of omission. Witnesses forget details of what happened.
• Errors of commission. Witnesses often try to make up for their memory gaps—that is, their forgetting—by unintentionally introducing details that didn’t actually take place.

What variables influence the accuracy of eyewitness memory?

Numerous variables influence the accuracy of eyewitness memory. For example, according to authors such as Migueles and García (2014), witnesses remember events better than they do people.

For this reason, although many of them are able to remember the different moments of the crime in question, the details of the person who perpetrated these actions are usually less exact.

However, certain variables, such as the sex of the witness or stereotypes, tend to influence the accuracy of the eyewitness testimony.

The violence of crime

Authors such as Clifford and Hollin (1978, in Pajon and Walsh, 2017) argue that extremely high levels of arousal can negatively affect witness recall.

Thus, rather violent crimes are remembered less successfully and accurately than those that developed under non-violent conditions. This can be inconvenient insofar as the most violent events are those in which the witness’s memory needs to be more exact.

Male or female witnesses

If you have two witnesses, a woman, and a man, and only one can be called to the stand, the psychology of eyewitness testimony would suggest the woman take the stand.

Nevertheless, according to Clifford and Hollin (1978), men remember violent events much more accurately than women while women seem to more accurately recall the non-violent ones.

It seems that, as a rule, women are much more reliable when it comes to remembering details about the person and not about the event. They better recognize the features of the subject in question. For example, their clothing and general physical appearance, regardless of whether the suspect is male or female.

On the other hand, men recognize voices better than women.

Don’t use a child as a witness

Age is another variable that influences the reliability of eyewitness memory. Children are much less reliable than adolescents, and adolescents less than adults. Memory reliability seems to stabilize at 17 years (Dent, 1978, in Santos et al., 2018).

Children are greatly influenced by the questions of their interrogators. Whether they be judges, lawyers, or police officers, depending on the nature and direction of the issues, they can alter a child’s memory.

Cops don’t have the best memories

Some studies suggest that police officers are the best witnesses because they have a greater memory capacity than civilians, but this isn’t the case.

Santos et al. (2018) argue that, although police officers are more accurate when it comes to detailing aspects such as physical appearance, weapons used, etc., this only lasts for a short period of time. In fact, they make more errors of commission than civilians in the long run. That’s because they’re unable to differentiate between other cases they have and mix up their memories.

The judge of memory: the credibility of the memory of the witness

Wells and Lindsay (1983) proposed a model of credibility that introduced insights from metamemory to determine whether or not people are accurate in their eyewitness testimony. It studied three types of information in eyewitness testimony.

• Conditional information. The authors claimed that the conditions of the person at the time the crime took place are extremely relevant. For instance, individual differences, stimulus variables, etc. It has to be determined that, if another person found themselves in the situation in which the witness had been, would they be able to remember what the witness remembered? Conditional information also includes the biases and myths that people have about memory. We’ll describe this in the last section.
• Inter-subject and intra-subject agreement. Manzanero and Diges (1993) determine that the information provided by a subject must maintain a certain internal consistency throughout the statement (intra-subject agreement). However, it must also maintain a degree of agreement with other details described by other subjects (intersubject agreement).
• Witness response biases. People tend to always identify or testify in the same direction, regardless of the objective variables of accuracy. Furthermore, the memory tends to detect these biases poorly, and gets carried away by details such as fillers, set phrases, pauses between phrases, etc, when these don’t necessarily indicate anything.

The myths about the witnesses

To conclude, we’ll cite some of the misconceptions that Mira (1989) identified the general population possesses regarding witnesses.

• Witnesses can identify in detail a person they’ve only seen for an instant, even after a long time has passed.
• Hypnosis is a technique used by police officers and it gives spectacular results. In addition, hypnosis guarantees the credibility of the witness.
• Police officers are the best witnesses.
• The threat of aggression—for example, being pointed at by a revolver— doesn’t influence the quality of the testimony.
• In an accident, the state in which the vehicle was left is better remembered. In actual fact, the only thing that doesn’t seem to get distorted over time is the place where the accident happened.
• Women are worse witnesses than men.

Eyewitness testimony often plays a fundamental role in deciding a sentence. Now we know more about how human memory works, the method for collecting witness testimonies has been greatly improved. It involves trying to avoid the contamination of memories as far as is possible.