arousal, anxiety and weapon focus

• what is the Yerkes-Dodson Law (1908)?

  an increase in psychological arousal improves performance on any given task but only up to an optimum point. after that performance declines.

  • arousal has a detrimental effect on memory. if we witness a crime and become so anxious/aroused, our memory will be impacted and the reliability of EWT is diminished
• catastrophe theory?

  Deffenbacher (1994), include levels of anxiety to Yerkes-Dodson law. high levels of physiological arousal are linked to anxiety (unpleasant cognitive state where the fear of something bad is going to happen). essentially when anxiety becomes so intense a catastrophic drop in cognitive performance drops, affecting memory performance
• different forms of anxiety?

  state: temporary feelings of anxiety (confronted by a large animal) causes a fight/flight response which is detrimental to accurate accounts of memory.

  trait: someone is anxious by nature and it is a part of their personality. levels of anxiety may become so high they recall very little of what they witness
• weapon focus?

  an eyewitness concentration on a weapon to the exclusion of other details of the crime
• weapon focus effect evidence for?

  • Loftus, Loftus and Messo (1987), 36 students watch a slide show of 18 scenes in a fast food restaurant (1.5 second shown). customer showed either cheque or gun to cashier. eye movement measured by EOG. longer eye fixation on gun (3.72 sec -> 2.44 sec) and less accurate photo recognition of person at cashier (11.1% -> 38.9%).

  gun arouses more anxiety
• weapon focus effect evidence against?

  • Pickel (1998), weapon focus occurs since presence of weapon is unusual in life. unusualness makes us focus on it. a man carried raw chicken to pay cashier at hairdresser and showed similarly poor recall (still evidence of weapon focus!)
  • Wagstaff (2003), coded police interviews from witnesses/victims of various crimes. interviews compared against police description of primary suspect and found no evidence of weapon effect on accuracy of EWT recall

  lab experiments also lack ecological validity and are artificial.
• Fawcett (2013)?

  meta analysis, presence of weapon consistently demonstrated negative effect on EWT in controlled and real life situations. testimonys are seen as unreliable with this evidence
• field case study in EWT?

  Yuille and Cutshall (1986), interviewed witnesses to real shooting in Canada. 13 witnesses interviewed by police by police and reinterviewed by researchers 4-5 months later.

  • accurate accounts of event seen despite 2 leading questions deliberately made in second interview, witnesses were also highly anxious (self reported anxiety was more than 5 on a 7 point scale) so effect of leading questions and weapon focus may be less pronounced when applied to real life situations)