In her study participants watched a thief enter a hairdressers carrying scissors (high threat, low surprise), handgun (high threat, high surprise), wallet (low threat, low surprise), and a raw chicken (low threat, high surprise).

Eyewitness accuracy was poorer in the high surprise conditions (chicken and handgun

Field Studies lack control

Researchers interview real-life witnesses some time after the event problem:misinformation and false memories

Post – Event Discussion may be an extraneous variable, this will affect accuracy of recall.

Demand Characteristics in Lab Studies

Most participants will work out the aim of the study or what is being asked of them, this impacts of the validity of the research.

Evaluation

Unusualness not anxiety

One limitation of the study by Johnson and Scott (facing page) is that it may not have tested anxiety.

The reason participants focused on the weapon may be because they were surprised at what they saw rather than scared. Kerri Pickel (1998) conducted an experiment using scissors, a handgun, a wallet or a raw chicken as the hand-held items in a hairdressing salon video (where scissors would be high anxiety, low unusualness). Eyewitness accuracy was significantly poorer in the high unusualness conditions (chicken and handgun.

This suggests that the weapon focus effect is due to unusualness rather than anxiety/threat and therefore tells us nothing specifically about the effects of anxiety on EWT.

Support for negative effects

One strength is evidence supporting the view that anxiety has a negative effect on the accuracy of recall.

The study by Tim Valentine and Jan Mesout (2009, see right) supports the research on weapon focus, finding negative effects on recall. The

into high- and low-anxiety groups. In this study anxiety clearly disrupted the participants ability to recall details about the actor in the London Dungeon's Labyrinth.

This suggests that a high level of anxiety does have a negative effect on the immediate eyewitness recall of a stressful event.

Support for positive effects

Another strength is evidence showing that anxiety can have positive effects on the accuracy of recall.

Sven-Ake Christianson and Birgitta Hübinette (1993) interviewed 58 witnesses to actual bank robberies in Sweden. Some of the witnesses were directly involved (e.g. bank workers) and some were indirectly involved (e.g. bystanders). The researchers assumed that those directly involved would experience the most anxiety. It was found that recall was more than 75% accurate across all witnesses. The direct victims (most anxious were even more accurate.

These findings from actual crimes confirm that anxiety does not reduce the accuracy of recall for eyewitnesses and may even enhance it.

Counterpoint Christianson and Hübinette interviewed their participants several months after the event (four to 15 months). The researchers therefore had no control over what happened to their participants in the intervening time (e.g. post-event discussions). The effects of anxiety may have been overwhelmed by these other factors and impossible to assess by the time the participants were interviewed.

Therefore it is possible that a lack of control over confounding variables may be responsible for these findings, invalidating their support.

Evaluation eXtra

Problems with inverted-U theory

The inverted-U theory appears to be a reasonable explanation of the contradictory findings linking anxiety with both increased and decreased eyewitness recall.

On the other hand it ignores the fact that anxiety has manv elements - cognitive, behavioural, emotional and physical. It focuses on just the last of these (physical arousal) and assumes this is the only aspect linked to EWT. But the way we think about

Weapons focus

The anxiety of seeing a weapon focuses all attention on the weapon and away from other aspects of the situation.

EWT is less accurate for all aspects of the situation except the weapon, so witnesses cannot describe, for example, the person holding the weapon.

The tunnel theory of memory

In stressful situations, our attention narrows to focus on one aspect of a situation; it is as if we had tunnel vision.

As with weapons focus, EWT is less accurate for all aspects of the situation except the most pertinent, which may be a weapon not a person.

Fight or flight response

A stressful event raises physiological arousal, thereby preparing the body for fight or flight.

Physiological arousal increases alertness, which improves memory for an event because we become more aware of cues in the situation.

The Yerkes-Dodson-Law

The relationship between emotional arousal and performance represents an inverted 'U' in which moderate stress/anxiety is associated with optimum performance while high or low levels of stress are associated with poor performance.

It explains why some research shows a negative relationship between anxiety and EWT whilst others show a positive relationship between them. In fact, according to this model, the most accurate witnessing takes place under medium levels of anxiety/stress.

Ethical Issues

Johnson and Scott’s study deceived participants about the nature of the experiment as they thought they were going to be interviewed – lack of protection from harm as they were exposed to man with a bloodied knife

Questions

1. Explain why this study is an example of a quasi-experiment. (2 marks)

2. Explain one limitation of a quasi-experiment. Refer to the study above in your answer. (2 marks)

3. Identify the sampling method used in this study and explain one strength of this method. (3 marks)

4. Questionnaires were used to collect the data. Write one closed question and one open question that could have been used in this study. (4 marks)

5. Select one other study of the effect of anxiety on the accuracy of EWT.

How do the findings compare with the findings in the London Dungeon study? (3 marks)

1. Explain what is meant by 'anxiety' in the context of eyewitness testimony.

[2 marks]

2. Briefly describe two factors that affect the accuracy of eyewitness testimony.

(6 marks]

3. Describe the effect of anxiety on the accuracy of eyewitness testimony.