Accuracy of EWT - Anxiety Flashcards
How does anxiety affect EWT
Anxiety has strong emotional and physical effects on eye witnesses. But it is not clear whether these effects make eyewitness recall better or worse. Research supports both possibilities.
However, according to Yerkes and Dodson (1908) the relationship between emotional arousal and performance looks like an inverted ‘U’. This inverted U theory states that performance will increase with stress, but only to a certain point, where it decreases drastically.
Deffenbacher (1983) applied the Yerkes-Dodson Law to EWT. Lower levels of anxiety produce lower levels of recall accuracy – but memory becomes more accurate as the level of anxiety experienced increases. However, there comes a point where the optimal level of anxiety is reached. This is the point of maximum accuracy. If an eyewitness experiences any more stress than this, then their recall of the event suffers a drastic decline.
In other words, too much or too less anxiety will affect recall, thus a medium amount of anxiety will aid the most accurate recall.
What is the weapon focus effect
High anxiety can be created through the weapon focus effect – for example, a crime may be committed and the eye witnesses will be watching the event. Suddenly, the perpetrator may pull out a weapon (e.g. a knife or a gun). Suddenly, the anxiety levels of the observers will begin to rise as their focus shifts from the crime to the weapon – this is known as the weapon-focus effect and has been used to test high anxiety.
Johnson and Scott ( experiment
participants sat outside a laboratory and heard one of 2 situations from inside
1) A friendly conversation followed by a man emerging carrying a pen with grease on his hands (low anxiety condition)
2) An argument, with smashing glass and overturned furniture followed by a man emerging with a blood stained paper knife (high anxiety condition)
All participants then had had to identify the man on the basis of 50 photos.
Johnson and Scott ( results
Witnesses were 49% accurate in identifying the man with the pen, compared to 33% accuracy with the knife. This shows that anxiety affected recall since when participants were in the high anxiety condition (the bloodied knife) this lead them to focus on the weapon rather than the face of the man. However, when participants were in the low anxiety condition (the greasy pen), they focused on the man’s face rather than the actual weapon/object (a greasy pen is harmless compared to the knife)
Conclusion: Anxiety generated by the weapon diverted attention away from the face of the man. This was called the ‘weapon-focus effect’. In fact, Steblay (1992) found in his meta-analysis of a variety of cases found that the presence of a weapon significantly reduces the chances of a person accurately identifying the person holding it.
Christianson and Hubinette theory on An example of high anxiety having a positive effect on accuracy of EWT
There is an alternative argument that says high anxiety/arousal creates more enduring ad accurate memories. This was shown in a study by Christianson and Hubinette (1993). In their study, they found evidence of enhanced recall when they questioned 58 real witnesses to a bank robbery in Sweden. The witnesses were either victims or bystanders. The interviews were conducted 4-15 months after the robberies. It was found that all witnesses showed generally good memories for details of the robbery itself (75% or more accurate recall). Those witnesses who were most anxious (the victims) had the best recall of all – suggesting that high anxiety actually enhanced accurate recall!
Christianson (1992) thus concluded that memory for negative emotional events is better than for neutral events.
As further support for the idea of high anxiety on accurate memory recall, Yuille and Cutshall (1986) found witnesses who had been most distressed at the time of a real-life shooting in Canada gave the most accurate account five months later. This suggest that high anxiety doesn’t necessarily result in poor memory recall.
Weaknesses of Anxiety as a factor affecting EWT
Weapon focus may not be caused by anxiety
A criticism of the weapon focus effect comes from Pickel (1998) who proposed that the reduced accuracy of identification could be due to surprise rather than anxiety – to test this she arranged for pps to watch a thief enter a hairdressing salon carrying scissors (high threat, low surprise), handgun (high threat, high surprise), wallet (low threat, low surprise) or a whole raw chicken (low threat, high surprise). Identification was least accurate in the high surprise conditions (e.g. Chicken) rather than the high threat conditions – this supports the view that the weapon focus effect is related to surprise (or unusualness) rather than anxiety.
Field studies sometimes lack control
Yuille and Cutshall’s and Christianson and Hubinette’s studies have the strength of being naturalistic studies- participants had seen a real crime making the study higher in ecological validity. However, because it is natural study confounding variables may have affected results. For example the people who were likely to have experienced the highest levels of anxiety may have been nearest to the incident so would have been able to see more clearly what happened. Witnesses recall may have also been affected by extraneous variables such as post-event discussion or information they read about the event afterwards. This makes it harder to make a conclusion about the effect of anxiety on EWT accuracy.
There are ethical issues with studies carried out on anxiety and EWT
Creating anxiety in pps is very risky – it is potentially unethical because it may subject pps to psychological harm purely for the purposes of research for example, in Johnson and Scott’s study some pps were subject to hearing an argument which they could not see – this may have caused the pps stress wondering what is going on – also when the man came out of the room with a bloody knife – this could have caused further stress – was this necessary? Moreover pps were deceived in the sense that they did not that the argument and the bloody pen was all staged. The question is, is it necessary for these studies to be carried out when there are real life events which create real levels of anxiety?
This is a more general problem of research into the effect of anxiety on EWT accuracy- for a lab study to be carried out anxiety must be caused deliberately (leading to a risk of psychological harm). Natural studies are obviously more ethical (as anxiety is not caused deliberately) but in natural studies experimenters have less control over variables which might affect results.
The Yerkes Dodson Law explanation is too simplistic
Anxiety is very difficult to define and measure accurately. One reason for this is that it has many elements – cognitive, behavioural, emotional and physical – however the Yerkes Dodson Law assumes that performance – in this case the eyewitness testimony is linked to physiological arousal – in this case anxiety. However, anxiety cannot always be measured through physiological means as anxiety can also be due to worry – this can be hard to measure through physiological (biological) means.
Individual differences
It could be that rather than anxiety affecting a person’s accuracy in recalling an event, it could be their personality characteristics for example, Bothwell et al (1987) found that neurotic (highly anxious) individuals were less accurate with their stress levels increased whereas stable individuals were more accurate when their stress levels increased. This study shows that there are individual differences in anxiety levels and accuracy of recall and it may not affect everyone in the same way.
Strengths of Anxiety as a factor affecting EWT
Support for negative effects - Valentine and Mesout support weapons focus. They measured heart rate when groups were exposed to an actor in the London Dungeons. The high heart rate group had a poorer recall of details, suggesting that anxiety has an effect on EWT.
Support for positive effects - Christianson and Hübinette interviewed witnesses to a crime in Sweden, including bystanders and those directly involved. They found that those who were directly involved in the crime (such as the bank clerk) had higher EWT. Accuracy of recall was 70% on average across all witnesses. This suggests that anxiety does not have a negative effect on EWT and instead may benefit it.
