How Eyewitnesses’ Memories Can Be Affected


By Catherine A. SandersonAmherst College

When you witness an event, you might have initially encoded and stored accurate information about what you saw or heard, but when trying to recall that information later on, you just don’t recall all of the details. In other words, eyewitnesses’ memories tend to decline with time, and it may be months, or even years, between someone witnessing a crime and the trial.

Two bystanders describing the crash scene for a police officer
Like everything else, memories tend to decline over time, so the eyewitnesses’ memory isn’t something the police could rely on. (Image:

Misleading Information Leads to False Memories

In multiple experiments, Elizabeth Loftus, a cognitive psychologist and memory expert, has shown that exposure to subtle misleading information can lead people to misremember their own life experiences. In one well-known study, students read written summaries of four eventsthree that they had actually experienced and a fourth that was entirely made up.

This fourth story, which was created based on realistic details provided by one of the student’s relatives to make it seem more believable, described a time in which the student had been lost in a mall or another public place when he or she was a small child. 

After reading each story, students were asked to write down anything else they remembered about the event or that they had no memory of the event occurring. Now, one of these events was entirely made up, yet one-third of the students reported having at least some memory of it occurring.

This study helps illustrate how eyewitnesses can become less accurate over time. Each time they’re questioned about the crime, their memories will slightly shift. This is particularly true if detectives ask leading questions or discuss the crime with other witnesses. And most eyewitnesses do talk to other witnesses, which leads to what’s known as “co-witness conformity”. 

As eyewitnesses discuss the event with each other, their individual memories of the event shift and can incorporate new details based on what someone else reports seeing or hearing even if they didn’t actually witness those details.

Questioning Can Shape the Eyewitness’ Memory

Even the words that police officers use when questioning an eyewitness can shape their memory of the event. In one study, participants were shown a video of two cars crashing and were then asked how fast the two cars were going before the crash. But the researcher varied which verb they used to describe the crash: 

A woman telling a police officer about a car accident
Witnesses might say something at the beginning of the interrogation but falsely remember something else later on. (Image:

“How fast were the cars going when they contacted each other” in one case, “hit each other” in another case, and “smashed into each other” in the third case. When the word contacted was used, the estimate was 30 miles per hour. When the word hit was used, the estimate was 34 miles per hour. And when the word smashed was used, the estimate was 41 miles per hour.

Then, in the second part of this study, the researchers called all of the participants one week later and asked one question: Had they seen broken glass at the scene of the accident? In reality, the video had not shown any broken glass. 

No one who’d been asked about the cars contacting each other or hitting each other answered this new question by saying that they remembered seeing glass. But of those who’d been asked about the cars smashing into each other, 32% falsely remembered seeing broken glass.

This article comes directly from content in the video series Introduction to PsychologyWatch it now, on Wondrium.

The Retrieval Process 

Problems with eyewitness identification can also occur at the third stage of memory, the retrieval process. Various environmental cues can lead us to recall memories inaccurately. How does this happen? One factor is the format of the lineup. 

Typically, eyewitnesses are either shown a set of photos or see a group of potential suspects in a live line-up, typically behind a wall of one-way glass. They are then asked to choose whether they recognize the person who committed the crime, and if so, to pick out that person.

But eyewitnesses often assume that the person must be present in the photos or line-up, or the police wouldn’t bother asking them to identify the person. They may therefore choose the person who best matches their memory of the suspect, which increases the likelihood that a witness will identify an innocent person who happens to bear a close resemblance to the real perpetrator.

The Effect of Positive Feedback

Even if an eyewitness isn’t confident about their selection initially, they can become more so over time. When people are given positive feedback about their identification, they become more confident in their judgment. For example, witness confidence increases after hearing that another person also identified that suspect. 

In one study, researchers staged a theft in front of a group of people and then had each person separately try to identify the suspect from a lineup of pictures. After the person had provided an identification, the researcher told them one of three things: That the other witness had picked the same person, a different person, or no one at all. 

When eyewitnesses are told that someone else has identified the same person, they become more confident in their judgment, whereas when they are told the other witness chose someone else or no one at all, they become less confident.

So, the serious potential problem for witness testimony is that our memories actually change while they are in storage. So, we might initially have encoded and stored accurate information, but then we are exposed to other information, perhaps something we read in a newspaper or hear from a friend, that shifts the memory to be less accurate. 

Memories are far from a perfect factual rendition of what actually happened. Instead, memories are reconstructed over time and new pieces of information can unintentionally alter what we remember.

Common Questions about How Eyewitnesses’ Memories Can Be Affected

Q: Is the eyewitness’s memory accurate enough to be relied on?

No, because studies proved that eyewitnesses‘ memories could decline with time, even if the person who witnesses an event successfully encodes and stores them.

Q: How can eyewitness’ memory be affected over time?

Exposing misrepresenting information can get people to even misremember their own experiences of life. Accordingly, eyewitnesses‘ memory can be misled during investigations and become less accurate as time goes by.

Q: How do eyewitnesses become more confident about their identification?

Sometimes eyewitnesses aren’t confident about who they’ve identified in the first place, but their confidence grows over time for many reasons. For example, when they hear another eyewitness also has identified the same person, or even after positive feedback about the identification.

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