eye-witness testimony

• weapon focus... 


  refers to an eyewitness' concentration on a weapon to the exclusion of other details of the crime
• loftus et al (1987)...


  showed participants a series of slides of a customer at a restaurant

  • version 1 = customer was holding a gun
  • version 2 = customer was holding a chequebook

  participants who were shown version 1 where much less likely to identify other features of the cusomer in an identify parade as they tended to focus more on the gun
• johnson and scott (1976)...


  participants sat in a waiting room and heard an argument coming from a nearby room

  • condition 1 = low-anxiety - man leaves holding a pen with grease on his hands
  • condition 2 = high-anxiety - participants heard breaking glass and then a man leaving with a paper knife covered in blood

  participants were then asked to pick out the man from a selection of 50 photographs

  low-anxiety condition = 49% accuracy

  high-anxiety condition = 33% accuracy
• what did johnson and scott's study demonstrate?

  that anxiety has a negative effect/impact on recall
• yville and cutshall (1986)...


  wanted to study the effects of stress on accurate recall

  13/21 witnesses from a crime took part 4/5 months post the incident

  witnesses were asked to rate their anxiety on a scale of 1-7

  those with the highest stress levels were the most accurate - 88% accuracy

  lowest stress-levels = 75% accuracy
• what does yville and cutshall's study argue?

  that anxiety can actually have a positive effect on recall
• what does the yerke-dobson law (1908) demonstrate?


  that there is an optimum level of anxiety in which recall is the best

  
• pickel (1998)…


  found that recall was poorer in specific circumstances - wanted to see if recall was affected by anxiety or unusualness
• what were the findings of pickel (1998)’s study?


  recall was significantly poorer in unusual conditions (gun and raw chicken)

  suggests that weapon focus is due to unusualness not anxiety
• what were the 4 objects in pickel’s study?

  scissors - high anxiety, low unusualness

  raw chicken - low anxiety, high unusualness

  gun - high anxiety, high unusualness

  wallet - low anxiety, low unusualness
• valentine and mesout (2009)…


  conducted a study in the horror labyrinth at the london dungeons

  visitors were separated into either a high/low condition - visitors would then self-report on their anxiety levels and wear a wireless heart monitor
• what were the findings from valentine and mesout’s study?


  when asked to describe a person from the labyrinth, the high anxiety group recalled the fewest correct details

  17% corrected identified the actor, compared with 75% in the low anxiety group

  suggests that anxiety has a negative effect on recall
• christianson and hubinette (1993)…


  interviewed 58 witnesses of actual ban robberies in Sweden

  recall was 75% accurate overall

  those directly involved/closest to the crime were the most accurate

  suggests that high anxiety does not reduce the accuracy of recall
• what is a counter argument to christianson and hubinette?

  participants were interviewed up to 15 months after the incident

  psychologists had no control over confounding variables - example = post-event discussion

  effects of anxiety may be overwhelmed by others factors
• what are some limitations of the yerkes-dobson law?


  although it’s a reasonable explanation for contradictory research, it ignores how complex anxiety is and how people each experience it in different ways (cognitive, behaviour, emotional, physical)

  the yerkes-dobson law just focuses on physical arousel, assuming that it’s the only aspect linked to EWT

  there could have been many extraneous variables that could have affected participants recall of events

  may subject participants to psychological harm
• cognitive interviews…


  designed to enhance retrieval of the original memory, designed to provide extra cues that might jog the witnesses memory
• fisher and geiselman (1992)…


  created the concept of a cognitive interview
• what are the 4 stages of a cognitive interview?

  1. report everything
  2. reinstate context
  3. change order
  4. change perspective
• report everything…


  every detail that you can remember you must report, even if it seems trivial
• reinstatement of context…


  mentally reinstate the context of the target event

  recall the scene, the weather, what you were wearing, what you were feeling, the preceding events
• change recall in reverse order…

  try to report the episode in reverse order, moving backwards and forwards in time
• recall from a changed perspective…

  try to describe the episode as if it as being viewed from different perspectives/viewpoints other than your own
• what are some evaluation points of cognitive interviews?


  • very time-consuming
  • specialist training is needed
  • CI may not be being used the same way in all police forces
  • police may need to build trust with witnesses before they are willing to report/fully open up
• milne and bull (2002)…


  found that using a combination of “report everything” and “mental reinstatement“, participants recall was significantly better
• köhnken et al (1999)…


  conducted a meta-analysis of 53 studies and found on average a 34% increase in amount of information generated in cognitive interviews
• what is a limitation of köhnken et al’s study?


  there was also a 61% increase in inaccurate information when compared with a standard interview, even with an 81% increase in correct information
• what are some limitations of the cognitive interview?


  • different police forces use different techniques from the CI method
  • very time-consuming
  • quality and quantity of CI training is an issue
  • prefers techniques that limit eye witness accounts
  • demands are placed on the interviewer to “probe” effectively
• what are some positives of the CI?


  • although CI produces an increase in false positives (recall of additional items), there is a bigger increase in the amount of correct information recalled
  • CI is valuable in reducing miscarriages of justice
• wright and holliday (2007)…


  investigated how age affects recall - the older the participant (75-95 years old), the less complete and accurate their recall is

  however, when using CI, the older participants recalled significantly greater without false positives
• loftus and palmer…

  asked students to watch a video of a car crash and then asked them a question about the speed of the car

  each group heard a different verb…

  • hit
  • collided
  • contacted
  • bumped
  • smashed
• what were the findings of loftus and palmer’s experiment?

  the leading question led to participants giving different answers

  “contacted” = 31.8 mph

  “smashed” = 40.5 mph
• what occurred in loftus and palmer’s follow-up experiment?

  tested whether or not the leading question led to a memory change

  found that those who had the verb “smashed” admitted to seeing broken glass on the floor
• post-event discussion…


  when eyewitnesses to a crime discuss their experiences and memories with each other
• what are some evaluation points of misleading information?


  • can be practically used in the justice system - police can be careful on how they phrase interview questions

  however loftus and palmer’s participants were watching a video which is much less stressful than actually being witness to a crime