Eyewitness Testimony Factors (Edexcel A-Level Psychology): Revision Notes

Eyewitness Testimony Factors

Introduction

Eyewitnesses are individuals who observe an event, such as a crime, as it occurs. Police typically document the witness's observations and may require them to testify in court, providing testimony to a judge and jury about what they witnessed during the incident.

Human memory is not as reliable as one might expect. Memory can be influenced by numerous factors, all of which affect the trustworthiness of testimony provided in court. Understanding these factors is essential for evaluating the reliability of eyewitness accounts.

Witness factors

Stress and arousal

Eyewitnesses experience considerable emotional stress when observing an event. Research suggests that whilst some arousal enhances performance in remembering information, excessive arousal or stress impairs memory accuracy.

The Yerkes-Dodson Law (1908)

The Yerkes-Dodson Law demonstrates an inverted U-shaped relationship between arousal and performance. This relationship can be expressed as:

$\text{Performance} = f(\text{Arousal})$

where the function $f$ creates an inverted U-shaped curve.

According to this principle:

• As arousal increases from low levels, performance improves
• There exists an optimum level of arousal that produces the best performance
• Beyond this optimum point, as arousal continues to increase, performance declines
• Being too relaxed results in poor performance, as does being excessively stressed

![Yerkes-Dodson Law diagram showing inverted U-curve with Performance on y-axis and Arousal (stress) on x-axis]

Evidence for stress effects

Valentine and Mesout (2009) conducted a study in the London Dungeon using real eyewitnesses to an event. Participants attended the attraction not knowing they would be required to recall what they saw after visiting the museum. This study can be considered more valid than laboratory experiments because it tested the effect of arousal on memory recall in a realistic setting.

The researchers aimed to investigate arousal effects using a real-life scenario. She compared this with laboratory experiments such as the Loftus et al. (1987) syringe study, which examined the weapon focus effect. In that study, recall of the event was greater when participants were approached by an experimenter holding a syringe rather than a pen. The syringe created a high-arousal situation, supporting the idea that arousal affects memory encoding.

However, research indicates that the Yerkes-Dodson Law does not universally apply. Recall within laboratory settings can be accurate, suggesting that low arousal in experimental conditions may not always impair accuracy. The Yerkes-Dodson Law also does not necessarily apply in field studies of witness accuracy involving real-life incidents. Mixed findings exist regarding recall within real-life situations.

Yuille and Cutshall (1986) investigated a real gunshop robbery and subsequent shooting in Canada. Real witnesses to the incident were interviewed, and their testimony was compared to police records of other evidence. The researchers discovered that witnesses retained detailed memories of the event and were not misled by researchers' leading questions. Their findings indicated that witnesses with the highest reported arousal levels provided the most accurate testimony. This may be explained not solely by arousal levels but because those experiencing the highest arousal were closest to the crime and therefore had a clearer view.

In contrast, Stanny and Johnson (2000) studied a high-arousal police officer training exercise involving a shooting scenario. They found that fewer details were recalled within this high-stress situation, suggesting that excessive arousal does not always create improved recall. Instead, arousal levels had exceeded the optimum point, becoming counterproductive.

Evaluation of stress and arousal research

Practical issues in research design and implementation:

Laboratory studies examining arousal effects are discussed in relation to their validity in measuring the true arousal experienced by real eyewitnesses. The Yerkes-Dodson curve demonstrates that students undertaking research in laboratory settings may not reach the critical level of optimum performance (that is, recall of an event). This occurs because they know what they are observing is not real.

Laboratory experiments possess the advantage of being highly controlled settings. For eyewitness testimony research, this level of control creates an artificial environment. The absence of extraneous variables that would typically exist in a real crime setting (such as background noise and reactions of other people) reduces the ecological validity of findings from laboratory settings.

Flashbulb memories

Flashbulb memories were proposed in the 1970s to describe the belief that memory almost captures a photographic record of events that have an emotional impact. It was hypothesised that this type of memory was unusually accurate and remained accurate over many years.

For example, people may be able to recall where they were when they learned about violent acts of the time, such as the 9/11 terrorist attack in 2001 or the 7/7 bombings of London in 2005, or when they learned of the death of well-known individuals such as Michael Jackson or Robin Williams. Hirst et al. (2009) investigated flashbulb memories of the 9/11 New York terrorist attack and demonstrated that our memories of these events will remain accurate for a period of time. However, as with other memories, the accuracy of recall fades over time.

Use of psychological knowledge within society

Understanding how we encode and later retrieve memories helps wider society. Flashbulb memories can explain why individuals still recall vivid incidents such as tragic accidents long after the event has occurred.

Similarly, this knowledge helps us to understand why recall for stressful situations remains for prolonged periods, due to the high arousal at the time. This provides an explanation for why individuals can suffer prolonged trauma, often known as post-traumatic stress disorder (PTSD), after witnessing a traumatic scene, even if they were only involved in that situation briefly.

Post-event information

Introduction and importance

The encoding of the event observed by a witness is equally important as the initial witnessing of the offence itself for maintaining accurate testimony. Witnesses are often interviewed over a period of time after the offence, and some time before a case may proceed to trial.

The experiences of the witness during this time period can impact what witnesses believe they saw during the offence. This can result in them providing inaccurate information at key moments, as other information can confuse the information they have already encoded.

During the period between a criminal event and a trial, a witness may encounter additional information about the event from various sources, including:

• The media
• Other witnesses
• Lawyers
• The police

We do not recall information in exactly the same form as it was encoded. Instead, there is a tendency to recall the main points or underlying meaning in a way that makes most sense to the individual. Information presented to witnesses after the event can influence a person's schema about what they think happened within the event, particularly if the event was unusual or outside their normal experience, making testimony less accurate.

The misinformation effect

Most of what we understand about the sustainability of adult eyewitness accounts comes from the work of Elizabeth Loftus. She is an American cognitive psychologist with an interest in memory. She conducted her own research in the 1970s and continues to research memory within legal contexts, including investigation of factors that can make eyewitness memory less reliable.

Leading questions

Leading questions are discussed in relation to the research of Elizabeth Loftus and John Palmer. They are a particularly important source of post-event information and can influence the accuracy of eyewitness recall.

Leading questions may come from numerous sources, including:

• The police during interviews
• Legal officials within a trial setting

They may be used unintentionally whilst attempting to gain information, or they may be used in court by solicitors who are attempting to confuse witnesses to support their client (the defendant). A verdict of not guilty can rest on the courts or the jury believing the witnesses are unreliable.

The findings of Yuille and Cutshall (1986) suggest that leading questions have limited effect on accuracy within real-life eyewitness accounts. Their research was based on a case study of a real gunshop robbery and subsequent shooting in Canada. Real witnesses to the shooting were interviewed about the incident, and this was compared to police records of other testimony. The researchers found that the witnesses had detailed memories of the event and were not misled by the researchers' leading questions.

Evaluation of leading questions research

Most research has examined the effect of questions relating to key parts of an event. For example, within Loftus and Palmer's (1974) work, they asked 'About how fast were the cars going when they hit each other?' Only limited research has been carried out to examine more open-ended questioning procedures to investigate the effect of misleading post-event information on adults' eyewitness accounts.

The Yuille and Cutshall (1986) study used only a small participant group. There is potential for participant variables to affect the findings of the study, and reliability is therefore reduced. However, the use of field studies such as this increases the ecological validity of the study and psychological understanding of the effect of leading questions on eyewitness testimony.

The use of laboratory investigation as a measure of eyewitness testimony yields different results from those undertaken with witnesses of real-life crimes. This suggests that caution should be applied in considering only the findings of laboratory studies in this area.

Laboratory experiments arguably minimise the emotional stress placed on a participant as they are aware the crime is not real, though it can still be distressing for some to witness crime images. Laboratory experiments do not create the same emotional reactions as watching a film of a crime compared to if witnesses were experiencing the crime themselves. They may also make participants less invested in trying to remember as much information as possible, as they know it was not a real crime.

Laboratory experiments have the advantage of being highly controlled settings. For eyewitness testimony research, this level of control creates an artificial environment. The absence of extraneous variables that would typically be found in a real crime setting, such as noises and reactions of other people, reduces the ecological validity of findings from laboratory settings.

Weapon focus

Definition

One factor that has been proven to affect recall of an event, and therefore eyewitness accuracy, is whether there is a weapon used within the offence they witness. There are two possible explanations for the effect of a weapon on eyewitness recall, which include the influence of stress experienced within the situation and the attention paid to the weapon.

Stress explanation

The Yerkes-Dodson Law is applicable to any crime situation, including those in which weapons are present. The high level of stress and arousal experienced by the eyewitness may have some influence on the amount of information they encode about the crime, and therefore the amount of information they are able to recall.

When there is a weapon present, it creates an optimum level of arousal, which assists the eyewitness in recalling information about the weapon, though not about other details within the situation. This suggests that arousal results in the individual focusing on the weapon to the detriment of other details, so making their recall limited to the weapon itself.

Attention explanation

A different explanation for the effect of weapon focus on the memory of an eyewitness is that of attention. Because a weapon is unusual in many cultures, it is focused on more closely at the expense of peripheral information.

Research evidence

Loftus et al. (1987)

Loftus et al. (1987) suggest that weapon focus occurs because the presence of a weapon focuses attention away from less dramatic visual images, such as the image of the perpetrator.

They showed participants a series of slides of a customer in a restaurant. In one version, the customer was holding a gun; in the other, the same customer held a chequebook. Participants who saw the gun version tended to focus on the weapon. As a result, they were less likely to identify the customer in an identity parade than those who had seen the chequebook version.

Kerri Pickel (1998)

Pickel argued that it is the unusualness of an object that draws our attention; in this case, the presence of a handgun, therefore assisting our recall of it, rather than the threat associated with it. This would explain why we might recall someone dressed as a superhero walking through a shopping centre on a busy day when we talk to friends about what we have done that day. There was no threat by the person dressed up, but it is not every day you see Batman at the local shops!

Pickel et al. (2006)

In 2006, Pickel et al. published another simulation study investigating whether awareness of the weapon-focus effect could diminish its effect. Participants were seated in a small classroom and informed that they were about to observe a short scene portrayed by actors.

However, participants were first provided with one of two brief lectures:

• (a) A lecture regarding weapon focus and how important it is to attend to perpetrator features instead of dwelling on any weapons they may carry, or
• (b) A lecture regarding eyewitness confidence and perceived credibility

In either case, a man interrupted the lecture by bursting into the classroom bearing a neutral object (a book) or a weapon (gun). The main finding was that participants presented with the lecture on eyewitness confidence (b) produced fewer correct details (and more incorrect details) related to the perpetrator in the weapon condition than in the neutral object condition.

However, object type had no effect on those presented with the weapon focus lecture (a). Pickel concluded that with proper instruction, the weapon-focus effect could be overcome.

Wagstaff et al. (2003)

In an attempt to overcome the fact that most weapon-focus research was simulated in a laboratory, Wagstaff et al. (2003) adopted a different approach by investigating information obtained about real-life events after they had occurred.

They coded police interviews taken from witnesses or victims of robberies, assaults and rapes investigated by two separate police forces in Britain. These interviews were compared against a police description of the primary suspect at the time of their arrest. They found no evidence of any effect of weapon presence on feature accuracy, therefore not supporting the weapon-focus effect.

Fawcett et al. (2013)

Fawcett et al. (2013) undertook a meta-analysis to identify what it is that causes our memories to be influenced when a weapon is present, in an attempt to clarify the various findings. They concluded that weapon presence consistently demonstrated a negative effect on both feature accuracy and identification accuracy under controlled conditions as well as within real-life situations.

Factors that complicate real-world research include how long the witness was exposed to the weapon, which is easily controlled within laboratory settings.

Evaluation of weapon focus research

Use of psychological knowledge in society

The findings of Pickel's various studies suggest that we should carefully consider the reliability of an eyewitness in court if the crime involved a weapon. Recent studies suggest that it may be possible to overcome the effect of weapon focus, which may increase the reliability of testimony.

The findings demonstrate that with appropriate training in weapon focus awareness, witnesses may provide more reliable testimony when weapons are involved. Police forces can use this knowledge to develop training programmes that help officers encode perpetrator details more effectively, even when weapons are present during an incident.

Remember!