Eyewitness Identification under Stress

Eyewitness Identification in Psychology

While we have all heard about eyewitness identification in a court setting, there is much more to identification than remembering who you saw.

Unfortunately, eyewitness identification is not as reliable as we would like it to be. There is a large weight placed on eyewitness identification in courts, but unfortunately, a wide variety of factors can influence eyewitness memories and identifications.

Factors Affecting Eyewitness Testimony in Psychology

Psychological research has found several significant factors affecting eyewitness testimony. These include misleading questions, confirmation bias, post-event discussions, and anxiety.

Let’s break them down.

An eyewitness might think that someone younger would commit a crime, leading their memory of the event to distort based on that belief.

This can happen in interviews with authorities right after a crime or during a court trial. Detectives, interviewers, or lawyers can ask (intentionally or unintentionally) misleading questions that can lead the eyewitness to second-guess their memory based on the question. In some cases, this can change someone’s memory.

Fig. 1. Questions in a courtroom can change someone’s memory. Wikimedia commons.

Post-event discussion can also change someone’s memory. Every time you remember an event, you pull it from your long-term memory storage. When it is pulled, it is susceptible to change. When talking with another eyewitness, you risk altering your memory.

Anxiety is a state of emotional and physical arousal caused by stress. Emotions such as worry and tension and physical changes such as increased heart rate and sweatiness occur. Both emotions and physical changes affect the accuracy and detail of eyewitness testimony.

Anxiety is produced in stressful situations such as accidents or crimes. You go through physiological and psychological changes that can affect your memory of the event and, therefore, your testimony’s reliability.

The Effect of Stress on Eyewitness Testimony and Memory

The strong emotional and physical effects of stress and anxiety can negatively or positively impact eyewitness testimony.

The Negative Effect of Anxiety

One theory is that stress and anxiety prevent you from focusing on the details of an event, making it harder to remember.

The Positive Effect of Anxiety

Another theory is that witnessing a stressful event that triggers anxiety induces the fight-or-flight response in your body, making you more alert. You would notice more details and thus remember the event better.

The Yerkes-Dodson law can explain the different effects of anxiety on memory, stating there is a relationship between stress and performance. Stress increases performance, but only up to a point. After that, excessive stress harms performance. Applied to eyewitness memory, this means that anxiety can improve memory performance, but only up to a certain point.

Eyewitness Identification under Stress in the London Dungeon

Let us now examine the Valentine and Mesout (2009) study on eyewitness identification under stress in the London Dungeon.

Fig. 2. The London Dungeon. Wikimedia commons.

The aim of this study was:

• To test the relationship between stress/anxiety and recall.

• To test whether or not high arousal/anxiety reduced the accuracy of eyewitness memory and eyewitness identification.

Design:

• Independent variable – stress/anxiety level.

• Dependent variable – accuracy of eyewitness identification.

Participants:

• The study used an opportunity sample (people who are available and willing to participate) of 56 participants (29 females, 27 males).

Materials:

• Self-report questionnaire for anxiety levels.

• Heart monitor.

Procedure:

1. Valentine and Mesout (2009) conducted a study in a real-world context in the Horror Labyrinth, London Dungeons.

2. There were jump scares, darkness, screams, gory models, etc., and participants encountered an actor dressed in scary clothes and makeup.

3. Researchers recorded the participants’ anxiety with both heart monitors.

4. Participants first experienced the dungeon and only then were informed of the purpose of the experiment. If they agreed to continue the study, they had to complete a self-report questionnaire about anxiety.

5. They had to describe an actor they had encountered in the labyrinth without guessing things they did not know (to avoid confirmation bias).

6. Then they had to identify him in a line of nine people and were told he might or might not be present in the line.

Findings:

Women reported higher levels of anxiety. The high anxiety group remembered less accurate details and made more errors. They also identified the actor less correctly (17%) than the low anxiety group (75%).

Conclusion:

Females have higher anxiety levels in stressful situations, which may affect eyewitness recall accuracy. In general, high anxiety levels decrease eyewitness identification accuracy.

Valentine and Mesout (2009) Evaluation

The strengths of the study were:

• It was a reliable study because the method used to measure anxiety (cardiac monitor) was objective.

• There were good controls because the same actor, questionnaire, and lineup were used each time.

• It was a field study, meaning it took place in a natural environment.

• The researchers validated the questionnaire by testing it on office workers to make sure it measured anxiety.

• Because both the questionnaire and the heart monitor were used, the study could compare anxiety traits (a personality trait that says how susceptible someone is to anxious situations) and state anxiety (temporary anxiety due to a specific situation).

• The researchers made sure to obtain informed consent before proceeding with the study, reminded participants of their right to withdraw, maintained data confidentiality, and debriefed participants.

A weakness of the study is:

• Because this was an opportunity sample of participants who willingly visited the London Dungeons, they were likely better able to cope with stress and anxiety. Therefore, people who experience greater anxiety might have different results than these participants.