Chapter 3. Eyewitness Testimony

Introduction

Eyewitness testimony is when a victim or bystander describes a specific event or suspect that is under investigation (e.g., in the case of a crime or car accident). Someone who witnessed a robbery might describe to the court the robber’s height, weight, skin color, etc. This type of information can be very influential in determining if the suspect is ultimately convicted of the crime. How reliable are eyewitness memories? Would you be a reliable eyewitness?

The following task is intended to illustrate issues regarding the accuracy of eyewitness testimonies, and memories more generally. You will watch a video of a crime. After the video you will read testimony from a credible eyewitness, and then complete a couple of questions about the event.

Instructions

For this task, watch the video of a robbery as if you are a bystander in the situation. Pay as much attention to the details of the robbery as possible. Note: The video has no sound.

Experiment

Results

Debriefing

The purpose of this task it to demonstrate that eyewitness memories are often not accurate because they can be influenced by other information to which we are exposed, such as what others say or news reports we might read. Eyewitness testimonies are very important information that courts use to determine whether a person is guilty of a crime or is responsible for an accident. Though we often feel confident when recalling our memories, our memories are reconstructions based on recalled cues rather than complete copies of events that occurred. Therefore, numerous variables can influence how we reconstruct our memories of people and events, and consequently, their accuracy. For example, a person who witnesses a crime is more likely to pick the wrong person from a lineup of potential suspects if the witness was under stress when she witnessed the crime or if the perpetrator was a member of different racial group than her (e.g., Brigham, Bennet, Meisner, & Mitchell, 2007; Deffenbacher, Bornstein, Penrod, & McGorty, 2004). Or the mere presence of a weapon can distort memory because it often attracts more attention than other objects (e.g., a cell phone), ultimately making people less likely to accurately remember other aspects of the event (e.g., the height of the perpetrator). This is known as the weapon focus effect (Steblay, 1992).

Sometimes people’s memories are influenced by misleading or incorrect information they receive after the event took place. This phenomenon is referred to as the misinformation effect. The current task was meant to illustrate the misinformation effect. Everyone saw the same video of the robbery. After the video, everyone read the testimony from a witness. For half of the people, the testimony describes four black men, two with guns, and one with facial hair, present at the robbery. The other half of participants read testimony suggesting that a fifth person was present and they were Hispanic, all wearing black hats, two had facial hair, and only one had a gun. We expected that the information in the testimony would bias what people recalled; for example, that there was an extra person present in the latter condition and that more people had guns in the former condition. In reality, there were only four people present and only three of them were wearing black hats. Two of them had guns and two of them had facial hair. Their race is not entirely clear, so they could be Hispanic, black, both, or from a different racial group entirely.

While this study may seem artificial, it has important implications. One study showed that for cases in which people were ultimately exonerated of their crime due to DNA evidence, over 70% of the time inaccurate eyewitness testimony helped convict them (Garrett, 2011). That is, innocent people are sometimes sent to prison because of the memory biases of eyewitnesses! Therefore, it is important for the psychological sciences to illuminate what types of information bias eyewitness testimonies in order for the legal system to develop tools to combat these biases.

Quiz