Can You Trust Eyewitness Testimony?

    Imagine being convicted of a crime you didn’t commit because an eyewitness insisted that they saw you do it. As an innocent person, you might wonder how such a thing could possibly happen. Is the eyewitness lying? Or just a case of mistaken identity?

    Or, what if you witnessed a crime and pointed out the suspect in a photo lineup to the police. Can you be 100 percent certain that the individual you think committed the crime is actually the perpetrator? What if you later learned that the person you identified actually had nothing to do with the crime?


    Eyewitness testimony can be complicated. In a legal sense, eyewitness testimony refers to an individual giving an account of an event they witnessed. It usually refers to a victim or bystander who is describing what they observed during a specific event under investigation, such as a robbery, accident or murder. Eyewitness testimony is critical to the justice system. When legal teams are able to present an eyewitness who can say, “I saw that individual committing the crime,” jurors are often compelled to believe them. Many convictions rest almost entirely on the word of an eyewitness. But there’s a big problem with eyewitness testimony—it can be inaccurate. And unfortunately, it can lead to wrongful convictions. While some research says eyewitness testimony is reliable, other studies have found problems with eyewitness’ ability to accurately recount the facts.

    Wrongful Convictions

    Whether an eyewitness saw a car speeding down the street just seconds after a crime was committed, or they were standing inside of a store when it was robbed, eyewitnesses are often the first resource police turn to when they need to gain information about a crime.

    Eyewitnesses may be asked to identify the suspect in a lineup, or they may be asked to give a description so a sketch artist can complete a composite drawing. Eyewitnesses often appear in court. Their statements play a vital role in securing criminal convictions. Police surveys show that eyewitness testimony is the main form of evidence in more than 20 percent of cases. Jurors tend to believe eyewitnesses. But studies show that many eyewitnesses are incorrect.

    According to the Innocence Project, 362 convictions have been overturned since 1989 after DNA evidence became available. Eyewitness testimony played a role in 70 percent of those wrongful convictions.

    Mistaken Identity

    One of the most famous cases of inaccurate eyewitness testimony involved Jennifer Thompson. In 1984, she was raped in her home in North Carolina. She was able to break free from her assailant and run to a nearby home. Another woman in her neighborhood was raped around the same time.

    Police believed the same man committed both rapes. Jennifer helped with the creation of a composite sketch of the rapist. Police developed a set of suspects and created a lineup.

    Ronald Cotton was charged and convicted of the rapes. He was sentenced to life in prison, plus 54 years. Thompson’s identification of him was the biggest factor in determining his guilt. After serving more than 10 years in prison, Cotton was exonerated. DNA testing determined that Cotton was not the perpetrator. The case became a go-to example of how eyewitness testimony can be unreliable. Yet, it’s often believed by jurors or judges who are tasked with determining a perpetrator’s guilt.

    Can Eyewitness Testimony Work?

    Despite clear examples of eyewitnesses pointing out the wrong person, some researchers insist you should trust eyewitness testimony—as long as law enforcement is careful about the way they elicit and respond to information.

    The Importance of Immediacy

    The authors of a 2018 study concluded, “Eyewitnesses typically provide reliable evidence on an initial, uncontaminated memory test, and this is true even for most of the wrongful convictions that were later reversed by DNA evidence.” The researchers argue that eyewitnesses are usually correct immediately after a crime. But the process of interviewing and questioning eyewitnesses contaminates their memories and may lead to wrongful convictions. The more times an eyewitness is questioned, the more likely their memories are to be contaminated. Being asked leading questions, hearing more information about a case from media or other witnesses, or simply relaying the story many times can influence an individual’s memory.

    The Role of Law Enforcement

    Rather than say “I don’t know” when asked a question, eager witnesses may attempt to fill in the blanks if they feel pressured by law enforcement to offer more information. Their expectations about what they thought should happen may also influence their memories about what actually happened.

    As research emerged about the unreliability of eyewitness testimony—and more DNA evidence revealed people who were wrongly convicted—a task force was created in the United States. The task force was made up of a panel of experts who were asked to create guidelines that would help law enforcement ensure that eyewitnesses are not pressured, unconsciously encouraged, or persuaded into giving false statements. In 1999, the Department of Justice produced a guide book for law enforcement that outlines the correct way to interview and interact with eyewitnesses. The guidebook outlines the factors that affect eyewitnesses and the strategies law enforcement officials can use to collect the most accurate information.

    How Questions Are Worded

    Eyewitness testimony isn’t always about picking out a perpetrator. Sometimes, eyewitnesses are asked about the facts of a case. And the words investigators use to gather the facts makes a big difference.

    Verb Use

    In a classic experiment in 1974, researchers showed students seven videos of traffic accidents. The videos ranged in duration from 5 to 30 seconds. After watching each accident, the students were asked to describe what they’d witnessed. They were asked specific questions such as, “About how fast were the cars going when they (smashed/collided, bumped/hit/contacted) each other?” The estimated speed was affected by the verb used to ask the question. When the word “contact” was used, students estimated much slower speeds than when the words “collided” or “smashed” were used. The researchers concluded that the words police officers use influence eyewitness testimony.

    Invented Details

    In another experiment, the researchers showed a one-minute lm that included four seconds of a multiple-vehicle traffic accident. Then, the students were questioned about the accident. Some students were asked, “How fast were the cars going when they hit each other?” Other students were asked, “How fast were the cars going when they smashed into one another?” were more likely to report seeing broken glass (even though there wasn’t any).

    Poor Eyesight

    Eyewitnesses often don’t have a good view of the event. Darkness, poor eyesight, an obstructed view, and long-distance may be factors in a witness’ ability to accurately recall events. But, eyewitnesses often want to be helpful. They may fill in the blanks with information or offer information they are uncertain about in an effort to help solve a case.

    Cross-Race Effect

    Studies consistently show that everyone has difficulty recognizing individuals from other racial or ethnic groups. It can be especially difficult for people in a majority population group. Researchers have found that people struggle to discriminate among faces that don’t resemble their faces. About 4 in 10 cases where individuals were exonerated for their crimes through DNA evidence involved cross-race misidentifications.

    Witness Bias

    Eyewitnesses have preconceived notions about the type of people who commit certain crimes. Consequently, their bias affects how much information they retain about a suspect. A 2013 study found that witnesses overwhelmingly remembered black suspects’ faces incorrectly when they witnessed crimes that are typically associated with black males, such as drive-by shootings. The eyewitness remembered black suspect’s faces much more accurately when they witnessed a crime that is usually associated with other races, such as serial killings. Another study found that witnesses tend to pair the worst crimes with people with darker skin. A 2016 study called “The Bad is Black Effect” found that when participants were asked to identify perpetrators of crimes, they were more likely to choose darker-skinned people when the crimes were more heinous. For less serious crimes, they pointed out lighter-skinned individuals.

    Memory Contamination

    Eyewitness memories can also be malleable; 86 percent of real eyewitnesses claim to have spoken with other eyewitnesses before speaking to law enforcement. These conversations can lead to “co-witness conformity.” When a fellow eyewitness shares something he saw, others might be inclined to say they saw it too even if they didn’t. Or, witnesses who aren’t sure what they saw may be susceptible to suggestions about what others say they witnessed. Memory decay can also be a problem. Months or years can pass before a case goes to trial and memories fade after time.


    The stress and trauma of being victimized or witnessing a crime can also influence an eye witness’s ability to recount the details. This can be especially true if a weapon was used. It’s common for witnesses to become focused on the weapon as opposed to the individual yielding the weapon. Studies have found that many victims or bystanders are able to accurately describe a gun or knife in great detail while having little knowledge of what the perpetrator looked like.

    Suspect Lineups

    In the United States, eyewitnesses are given a photo lineup and asked if they can identify the perpetrator among the pictures. Sometimes, live lineups are used where eyewitnesses view several people standing in a line (usually through a one-way window) and state whether the perpetrator they saw is present. Less often, a single photograph is shown to an eyewitness and asked, “Is this the perpetrator?” Single photos are said to get less accurate results as compared to lineups. Eyewitnesses sometimes choose the individual that best matches their memory of the perpetrator. It may lead to an increased likelihood of choosing an innocent suspect who happens to be a close match. In a popular experiment, psychologists Ray Malpass, Ph.D. and Patricia Devine, Ph.D. staged a crime in the middle of a college lecture. A male actor posed as a vandal who entered the lecture hall, exchanged heated words with the instructor and knocked over a rack of machines. The audience was then asked to identify the vandal in a lineup. The researchers found that the accuracy of the witnesses’ identifications depended on the instructions the researchers gave them. One group was told they had to choose among the suspects in the lineup while the other group was given the message that they did not have to make a choice.

    More importantly, that instruction did not hinder witnesses’ ability to make a correct identification. The feedback a witness is given also makes a difference. Studies show when law enforcement officials confirm a witness’s choice in a lineup, the witness’s confidence they picked the right person is indicated. If, however, feedback suggests the witness didn’t pick the “correct” suspect, the witnesses confidence wanes, which can affect future court testimony.