Factors affecting EWT - Anxiety

• How did Johnson and Scott investigate the effect of anxiety on EWT?

  They led participants to believe they were taking part in a lab study. Whilst seated in waiting area, they heard an argument in the next room. In 'low anxiety' condition the man then walked through the waiting area, carrying a pen. In 'high anxiety' they head the sound of breaking glass and man walked out of room with paper knife covered in blood.
• What were the results of the Johnson and Scott study?

  Participants picked out who they thought the perpetrator was from a set of 50 photos. 49% of participants who saw the man with the pen correctly identified him. 33% correctly identified the man with the knife. The tunnel theory of memory argues that witnesses attention narrows to focus on the weapon because it is a source of anxiety.
• What are the evaluation points for the Johnson and Scott study?

  • Contradicted by Yuille and Cutshall. Conducted study on real shooting & results showed that EWT was better in those who had experienced higher anxiety. Better as used a real life scenario. Suggests J&S isn't as valid.
  • Although waiting outside lab room, ppts may have anticipated something was happening, meaning a risk of demand characteristics which reduces internal validity
  • Broke many ethical guidelines. Deceived, not protected from harm, knife could have caused severe anxiety, especially is any ppts had experienced knife crime
• How did Yuille and Cutshall investigate the effect of anxiety on EWT?

  Studied an actual shooting which occurred in a gun shop in Canada. Shop owner shot a thief dead. There were 21 witnesses and 13 agreed to take part in study. 4-5 months after incident interviews were done with the participants and compared to original police interviews. Accuracy determined by number of details reported in each account. They were also asked to rate how anxious they were on a 7 point scale and whether they had suffered emotional problems since the event (e.g. sleep struggles, etc).
• What were the results of the Yuille and Cutshall study?

  Witnesses very accurate in accounts and there was little change in the account of detail recalled after 5 months. Some details less accurate, such as recollection of colours of items and age/height/weight estimates. Those who reported highest levels of stress were more accurate. Suggests that anxiety has no effect or even enhances EWT.
• What are the positive evaluation points of the Yuille and Cutshall study?

  • Findings reliable. Researchers replicated the police interviews to a great extent and achieved similar results
  • High validity - field study. True to life. Comparison between police and researcher interviews controlled by rigorous scoring system. High ecological validity as used real EWT.
  • Good ethics. Informed consent, little and mostly unsuccessful deception, had right to withdraw.
• What is the negative evaluation of the Yuille and Cutshall study?

  • Small sample size. Possibility of participant variables and sample bias. Plus, not all witnesses agreed to be re-interviewed. Therefore may not be a representative sample of the original participants as those most traumatised may not wish to be re-interviewed. If they had taken part, results of study may have been different.
• What is the Yerkes-Dodson law?


  Was designed as a way of explaining the contradicting results about how anxiety affects EWT. Suggests that lower levels of anxiety produce lower levels of recall accuracy, and then memory becomes more accurate as the level of anxiety increases. There is an optimal level of anxiety, which is the point of maximum accuracy. If a person experiences more arousal than this, then recall suffers a drastic decline.
• What is the tunnel theory?


  In stressful situations, our attention narrows to focus on one small aspect of the situation. This can make EWT less accurate for aspects of the situation which we were not focused on.
• What is the weapon effect?

  Anxiety caused by seeing a weapon focuses all attention on the weapon and away from other aspects of the situation. Makes EWT less accurate for all aspects of the situation except for the weapon.
• How does fight or flight affect EWT?

  This is our response to stress which prepares our body to fight or to run away. Physiological arousal increases alertness, which may improve memory for an event because we become more aware of cues in the situation.
• Evaluation of the role of anxiety in EWT:

  • Research into effect of anxiety in EWT has added to understanding of what happens in real-life witnesses and has increased their credibility in court
  • Investigating anxiety raises ethical issues which means it is often best to use real events (e.g. Yuille and Cutshall) however asking participants to recall their experience may be stressful
  • Research findings in this area appear to be contradictory - some suggest it improves and some suggest it worsens EWT, however Yerkes-Dodson law may explain the contradiction.