Anxiety affecting EWT

• What can mislead eyewitness testimony?

  Leading questions or post-event discussion
• What is weapons focus?

  Concentration on a weapon reduces recall
• What research was done that suggesting anxiety has a negative effect on recall?

  • Johnson and Scott in 1976, got participants that believed they were taking part in a lab study they seated them in a waiting room.
  • There were two conditions to this study, one in a low-anxiety environment where they overheard a casual condition in the next room and then saw a man walk past them carrying a pen and grease on his hands
  • The other high anxiety condition consisted of participants overhearing a heated argument, with the sound of breaking glass, then a man walked out of the room carrying a knife covered in blood
• What were the findings of Johnson and Scott's research?

  • The participants were later asked to pick out the man from their condition from 50 photos
  • 49% of those who had seen the man carrying the pen were able to identify him.
  • Whereas in the high anxiety condition with the knife, identification pf the man dropped to 33%.
  • This caused the suggestion of the tunnel theory of memory and weapon focus, where memory focuses on central events e.g. the weapon and reduces recall of the criminal
  • This suggests that anxiety has a negative effect on recall
• What research was done that suggests that anxiety has a positive effect on recall?

  • Yuille and Cutshall in 1986 conducted a study of an actual shooting in a gun shop in Vancouver Canada where the owner shot a thief dead.
  • There were 21 witnesses and 13 took part in the study, They were interviewed four to five months after the incident and these interviews were compared with the original police interviews that were conducted at the time of the shooting.
  • Accuracy was determined by the number of details reported in each account
  • The participants were also asked to rate how stressed they had felt at the time of the incident of a 7 point scale, and whether they had any emotional problems since the event (e.g. sleeplessness)
• Findings and Conclusion of Yuille and Cutshall's study?

  • That there was little change in the amount recalled or accuracy after five months , however some details were less accurate such as recollection of the colour of items and the age, height and weight estimates of the suspect.
  • Those participants who reported the highest levels of stress were most accurate with 88% accuracy compared to 75% for the less stressed group
  • This suggests that anxiety does not have a detrimental effect on the accuracy of eyewitness memory in real-world context and could even enhance it.
• How can the contradictory findings on the affects of anxiety be explained?

  • It can be explained by Yerkes and Dodson's (1908) inverted U law - where the relationship between emotional arousal and performance looks like an inverted U
  • Deffenbacher in 1983 uses the Yerkes-Dodson Law to explain the findings of 21 studies of EWT with contradictory effects of anxiety
  • He suggested that when we witness a crime or accident we become emotionally and physically aroused e.g. emotionally through anxiety and physical through the fight or flight response
  • Lower anxiety/arousal produce lower levels of recall accuracy and then memory becomes more accurate as the level of anxiety/arousal increases but only up to a certain point of maximum accuracy which is then at the optimal level of anxiety.
  • If an person/eyewitness experiences any more anxiety/arousal their recall suffers a drastic decline
• Research into the effects of anxiety having a negative effect on accuracy of EWT?

  Procedure: Johnson and Scott in 1976 got participants to believe they were taking part in a lab study, they seated them in a waiting room in to separate conditions to actually measure the effect of anxiety on EWT

  • There were two conditions to the study, one with low anxiety and the other with high anxiety
  • In the low anxiety condition participants overheard a casual conversation in the next room and then saw a man walk past them carrying a pen and with grease on his hands
  • In the high anxiety condition the participants overheard a heated argument accompanied by the sound of broken glass, followed by a man holding a knife covered in blood
• What were the findings and conclusions from Johnson and Scott's study?

  • The participants were later asked to pick out the man from the conditions from a set of 50 photos
  • In the low anxiety group, 49% of the participants were able to identify the man holding the pen
  • Whereas in the high-anxiety group only 33% of participants could identify the man
  • This could be explained by the tunnel theory of memory which argues that people have an enhance memory for central events, with weapon focus also having an influence
• Research into anxiety having a positive effect on EWT?

  • Yuille and Cutshall in 1986 conducted a study of an actual shooting in a gun shop in Vancouver Canada, where the shop owner shot the thief dead.
  • There were 21 witnesses with 13 taking part in the Study
  • The participants were interviewed four to five months after the incident, with these interviews being compared to original police studies done on the participants at the time of the shooting.
  • The researchers measured accuracy by the number of details reported in each account, witnesses were also asked to rate how stressed they had felt at the time of the incident on a 7 point scale, and whether they had any emotional problems since the event like sleeplessness