Factors Affecting Accuracy of EWT: anxiety

• conflicting evidence


  lab-based studies have generally shown impaired recall in people who have witnessed unpleasant or anxiety-inducing situations

  however, other research into real-life incidents involving high levels of stress, have shown that in such situations, memory can be detailed, accurate and long-lasting
• Deffenbacher


  one of the first to investigate the link between anxiety and EWT and after reviewing 21 studies, he found that accuracy is poor when emotional arousal is either high or low, but is better under conditions of moderate arousal
• Yerkes-Dodson Law

  
• Johnson and Scott - weapons focus effect

  P: led ppts to believe they were going to take part in a lab study

  while seated in a waiting room ppts heard an argument in the next room

  'low anxiety' condition -> a man walked through the waiting area: carrying a pen and with grease on his hands

  other ppts overheard the same argument -> this one accompanies by the sound of breaking glass - man walked out holding a paper knife covered in blood ('high anxiety' condition)

  F: ppts picked out the man from 50 photos

  49% of ppts who saw the man with the pen were able to identify him.

  33% for the man with the blood-covered knife

  This research shows that - the tunnel theory of memory argues that witnesses attention narrows to focus on a weapon -> source of anxiety
• Yuille and Cutshall


  P: Yuille and Cutshall conducted a study of a real-life shooting in a gun shop in Vancouver

  shop owner shot a thief dead

  21 witnesses - 13 agreed to take part in the study

  interviews were had 4-5 months after incident -> compared with original police interviews

  witness were also asked to rate their stress levels at the time of the incident

  F: witnesses were very accurate in their accounts

  little change in accuracy after 5 months

  these ppts who reported the highest levels of stress were most accurate (about 88% compared to 75% for the less stressed group)
• Weakness - ecological validity (Johnson & Scott)

  although the ppts were waiting in the reception area outside the lab, they may have anticipated that something was going to happen, which could've affected the accuracy of their judgements.

  Furthermore, the results from real-life case studies/natural experiments refute the findings of Johnson & Scott and suggest the results don't represent real-life cases of extreme anxiety
• Weakness - individual differences levels of anxiety

  individual weren't fully accounted for in Johnson and Scott's research.

  level of anxiety varies based on factors like personality and past experiences, which could affect the accuracy of EWT and undermine the internal validity of the study.

  Furthermore, several ethical guidelines were broken. ppts were deceived about the nature of the experiment and not protected from harm

  Some of the ppts saw a man holding a bloodied knife, which could've caused extreme anxiety

  This is an issue as these ppts may have left the experiment feeling exceptionally anxious, especially if they had been involved in knife crime
• Strength - research support: Christianson and Hubinette

  interviewed 58 witnesses to real bank robbery in Sweden.

  some of the witnesses had been onlookers or customers in the bank and other were bank employees who had been directly threatened or subjected to violence during the robberies

  Findings: all the victims were more than 75% accurate in their recall of the robbers' clothing and behaviour, and the accuracy was still evident 15months later

  In some cases, recall was even more accurate for those directly involved. This therefore suggests that anxiety can enhance EWT
• Strength - ecological validity of natural experiments

  natural experiments into EWTs have an advantage over lab experiments as they have high ecological validity.

  in lab studies, ppts are exposed to unrealistic scenarios presented in an unrealistic way

  Real world events are sudden unexpected, have high levels of emotion and stress involved, and provide the only real way to test how accurately witnesses recalled events.

  HOWEVER, they also lack control over extraneous variables such as witnesses discussing the event with one another, being interviewed by police, and reading about the event in the news.

  Both lab and natural experiments are therefore important, but it's interesting how the methods provide contrasting results about the effect of anxiety on EWT