Psych: EWT and Anxiety

• JOHNSON & SCOTT (1976)


  Researcher who conducted a study
• Conducted a lab study where they split pps.

  1. 2 groups

  2. Group 1 - low anxiety condition

  3. Group 2 - high anxiety condition
• Independent groups/measures


  • Participants were split into separate groups and measured independently
• Low anxiety condition


  • Sat in a waiting room, overheard a casual conversation, saw a man walk past with grease on his hands
• High anxiety condition


  • Overheard a heated argument and the sound of breaking glass, saw a man walk past carrying a knife with blood on his hands
• 49% of participants from group 1 could accurately identify the man
• 33% of participants from group 2 accurately identified the man
• Tunnel Vision Theory


  Focus on the weapon/the danger
• Conducted a study on an actual shooting in Vancouver


  1. Shop owner shot a thief, killing him in front of 21 witnesses

  2. 13 took part in the study

  3. Interviewed them 4-6 months after the incident and compared with one original interview
• Witnesses were very accurate in their accounts and there was little change in the amount of accuracy of recall after 6 months
• The participants who reported the highest levels of anxiety were the most accurate (88% compared to 75% for lower anxiety)
• The Yerkes-Dodson Law can be considered as an overly-simplified explanation of anxiety because it does not take into account the multiple factors which make up arousal i.e. cognitive, behavioural, emotional etc.
• Anxiety


  A physiological response to external pressures, characterised by an increased heart rate, vasoconstriction of blood vessels, increased sweat production etc.
• Anxiety effect on eyewitness


  Can have either a positive or negative effect on the accuracy of EWT
• Johnson and Scott (1976)


  • Demonstrated that anxiety has a negative effect on the accuracy of EWT
  • High-anxiety condition overheard a heated argument in the neighbouring room, with the sound of smashing glass and a man walking through the waiting room with a bloody paper-knife, as opposed to a greasy pen in the low-anxiety condition
  • Participants in the high-anxiety condition experienced 16% lower rates of accurate recall, compared to the low-anxiety condition
• Yuille and Cutshall (1986)

  • Demonstrated the positive effect of anxiety on the accuracy of EWT
  • Followed up 13 eyewitnesses, 5 months after a real-life shooting at a shop in Canada
  • Eyewitness accuracy was still high after this period, with an 11% higher accuracy of recall for those eyewitnesses who ranked their anxiety as 'high' (compared to 'low') at the time of the shooting and using a 7-point anxiety scale
  • There were, however, small discrepancies over estimates of height, weight and clothing