Eyewitness Testimony and the Misinformation Effect: A Study on the Accuracy of Recall

Background and Hypotheses

Task:

Social scientists have long been interested in the accuracy of eyewitness testimony. Several studies over the past few decades have demonstrated that eyewitnesses are not always accurate (e.g., Buckhout, 1974; Bornstein & Zickafoose, 1999). More recently, many individuals have filed appeals based on deoxyribonucleic acid (DNA) evidence. Of those acquitted on this basis, 78 percent had originally been convicted based on strong eyewitness testimony (Stambor, 2006). One reason witnesses may err when recalling information about a criminal is the misinformation effect, which involves "incorporating 'misinformation' into one's memory of the event after receiving misleading information about it" (Myers, 2008). Elizabeth Loftus (1978, 1979a, 1979b, 2001) and her associates have repeatedly demonstrated this effect, finding that memory can be "constructed" based on suggestive questions and information given after the fact. Other factors that play a role in our ability to recall information are decay and stress. Shapiro & Penrod (1986) presented evidence that suggests memory may decay over time, while other researchers have found that as stress increases, the accuracy of recall decreases (Deffenbacher, Bornstein, Penrod, & McGorty, 2004; Payne, Nadel, Allen, Thomas, & Jacobs, 2002).

Hypotheses

Given what we have learned through the literature review, our hypotheses are:

There will be a relationship between the type of information conveyed (a misinformation effect) and the accuracy of recall about the color of the vehicle.

Memory may decay over time.

The level of stress will affect recall.

There will be a relationship between the level of stress and confidence, such that confidence declines as stress rises.

Method

Participants: You will complete this as a part of your final project. This section should be completed at the end of Week 4.

Procedures

Participants are randomly assigned to one of three levels of stress: high stress, where they are writing a final exam immediately following their participation in the experiment; medium stress, where they are writing a final exam the day following their participation; and low stress, where their participation comes two weeks prior to their final exam. They are shown one of two different versions of a video of a bank robbery and instructed to pay close attention to detail.

All versions share the same beginning scenario, with two individuals entering a bank to rob it. The first individual (individual #1) is 5'10" tall and of medium build, wearing blue jeans, a black leather jacket, and black tennis shoes. This individual is wearing a ski mask with the holes around the eyes large enough for the color of the skin, which is white or light colored, to be visible. The second individual (individual #2) is 6'2" and heavyset, wearing black sweat pants, a red jacket, and dark work boots. This individual is wearing a ski mask identical to that of individual #1. The skin around the eyes is dark. No other skin is visible on either individual. Individual #1 walks to the window and hands the teller a note, bringing up the right hand, which is in the pocket, to simulate a gun. It is unknown whether an actual gun was used. Individual #2 stays back a step as if keeping watch. After the teller gives money to the robber, the two

Robbers leave the bank, jump into a car waiting at the curb, and drive away. In version #1, the car is blue. In version #2, the car is green.

Following the viewing of the video, each participant meets an individual in the waiting room. This individual (actually a confederate of the experimenter) states that he or she had lost something and had come back to see whether the experimenter found it. The individual begins a conversation about the video and says, "Did you see that blue (or green, depending on the condition) car they were driving?” Half the time, this question is congruent (the color mentioned by the confederate matches the color shown in the video). And half the time, the color is incongruent (the color mentioned by the confederate is different from that visible in the video).
 
Measures

At the end of this conversation, the confederate leaves, and the participant is asked by the experimenter to complete a short questionnaire to measure his or her memory of the details in the video. This questionnaire consists of fifteen fill-in-the blank questions where participants are asked questions, such as "What kind of pants was the individual who asked for the money wearing?" The participant must write what he or she recalls or "unknown" if uncertain about the response. Each correct answer is given one point, and the points are added to create a continuous measure of recall as the dependent variable. Scores on this measure can range from 0 to 15. This questionnaire is given again two weeks later, and a third time after one month.

Participants are also asked to rate their confidence in their recall of each item on a scale of 1 to 10, with one meaning very little confidence and 10 meaning a great deal of confidence. These items are added to create an overall confidence score, with higher scores indicating higher levels of confidence. Scores on this measure can range from 15 to 150.

The misinformation effect is stored in a variable named “recall color.” Recall color is scored as "Correct" if participants correctly identify the color of the car they had seen in the video and "Incorrect" if they incorrectly identify the color.
 
Finally, all participants complete a short questionnaire to measure their stress levels. This is necessary to check the stress manipulation and ensure it was effective. Possible scores on this measure range from 0 to 25, with higher scores indicating higher levels of stress.
 
Results

You will complete this as a part of your final project. Include the results of all analyses conducted to test hypotheses in Weeks 7, 8, 9, and 10.

Discussion

You will complete this as a part of your final project. The discussion should be written in Week 10, after all results are in. Be sure to discuss your results in relation to the information you learned in the literature review (introduction) and in relation to your hypotheses.