Eyewitness testimony: anxiety

• Anxiety has strong emotional and physical effects. But it is not clear whether these effects make eyewitness recall better or worse.
• Anxiety creates physiological arousal in the body which prevents us paying attention to important cues, so recall is worse. One approach to studying anxiety and eyewitness testimony is to look at the effects of the presence of a weapon which creates anxiety. This leads to a focus on the weapon, reducing a witness' recall for other details of the event.
• Johnson and Scott had participants believe they were taking part in a lab study. While seated in the waiting room participants in the low-anxiety condition heard a casual conversation in the next room and saw a man walk past carrying a pen with grease on his hands. Other participants heard a heated argument, accompanied by the sound of breaking glass and a man walking out holding a knife covered in blood.
• Johnson and Scott later asked the participants to pick out the man from a set of 50 photos, 49% who had seen the man carrying a pen correctly identified him. Only 33% of those who saw a man carrying a knife could correctly identify him. The tunnel theory of memory argues that people have enhanced memory for central events. Weapon focus as a result of anxiety can have this effect.
• Witnessing a stressful event creates anxiety through physiological arousal within the body. The fight or flight response is triggered, increasing alertness. This may improve memory for the event as we become more aware of cues in the situation.
• Yuille and Cutshall conducted a study of an actual shooting in a shop in Canada. The shop owner shot a thief dead. There were 21 witnesses- 13 took part in the study. They were interviewed 4-5 months after the incident and these interviews were compared to the original police interviews at the time of the shooting. The witnesses were also asked how stressed they had felt at the time and whether they had any emotional problems since the event.
• Yuille and Cutshall found the witnesses were very accurate in their accounts and there was little change in the amount they recalled after 5 months. Those who reported the highest levels of stress were most accurate. This suggests anxiety does not have a detrimental effect on the accuracy of eyewitness memory in a real-world context and may even enhance it.
• According to Yerkes and Dodson the relationship between emotional arousal and performance looks like an 'inverted U'.
• Deffenbacher reviewed 21 studies of EWT and noted contradictory findings on the effects of anxiety. He used the Yerkes-Dodson Law to explain the findings. Lower levels of anxiety produce lower levels of recall accuracy and then memory becomes more accurate as the level of anxiety increases. However, there is an optimal level of anxiety, which is the point of maximum accuracy. If a person experiences any more anxiety, then their recall starts to decline again.
• The study by Johnson and Scott 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. Pickel conducted an experiment using scissors, a handgun, a wallet and raw chicken as the hand-held items in a hairdressing video. Eyewitness accuracy was significantly poorer in the high unusualness conditions (chicken and handgun). This suggests weapon focus effect is due to unusualness rather than anxiety and therefore tells us nothing specifically about the effects of anxiety on EWT.
• There is evidence to support the view that anxiety has a negative effect on the accuracy of recall. Valentine and Mesout used an objective measure (heart rate) to divide participants into high and low anxiety groups. In this study anxiety clearly disrupted the participants' ability to recall and describe a person encountered in the Horror Labyrinth at the London Dungeon. This suggests that a high level of anxiety does have a negative effect on the immediate eyewitness recall of a stressful event.
• There is evidence showing that anxiety can have positive effects on the accuracy of recall. Christianson and Hübinette interviewed 58 witnesses to actual bank robberies. Some of the witnesses were directly involved and some were indirectly involved. The researchers assumed that those involved directly would experience the most anxiety. It was found that recall was more than 75% accurate across all witnesses. The direct victims were even more accurate. These findings confirm that anxiety does not reduce the accuracy of recall for eyewitnesses and may even enhance it.
• However, Christianson and Hübinette interviewed their participants several months after the event. The researchers therefore had no control over what happened to their participants in the intervening time (e.g. post-event discussion). The effects of anxiety may have been overwhelmed by these other factors and impossible to assess by the time participants were interviewed. Therefore it is possible that a lack of control over confounding variables may be responsible for these findings, invalidating their support.