Accuracy of EWT

• Factors that affect accuracy

  • Anxiety - unpleasant state of emotional arousal
  • can have a negative effect on the EWT
• Johnson and Scott


  • Ps thought that they were taking part in a lab experiment
  • When they were in the waiting room, they heard an argument in the next door area
  • LOW ANXIETY CONDITION - a man walks through the room carrying a pen with grease in his hands
  • HIGH ANXIETY CONDITION- a man walked out carrying a paper knife covered in blood

  Ps had to pick the man out from a set of 50 photos

  • pen condition - 49% recall
  • knife condition - 33% recall
• Pickel


  • investigated reason of low recall
  • confederates entered a hair dressing salon with a chicken, a wallet, a gun or scissors
  • when asked to identify the people entering the salon, the person holding the chicken was correctly identified significantly less than the other objects, including the gun
  • this showed that the low recall from weapon focus can be explained by both surprise and anxiety
• Other factors


  • age
  • personality
  • repression
• Yerkes Dodson


  • inverted U hypothesis- explains effect of anxiety on eyewitness
  • predcits that there is an optimum level of arousal for the best recall
  • a high or low level of arousal will not lead to a good recall

  
• Yerkes Dodson- research


  • lab experiments have ethical issues as the participants are made anxious deliberately in the study and are not protected fully from psychological harm

  Yulie and Cutshall

  • interviewed 13 witnesses to a fatal shooting
  • 4-5 months later, their recall was compared with their original statement
  • a seven point scale was used to measure stress and they were asked to recall their emotional stress since the event
  • high anxiety witnesses had less accurate recall than those with lower levels
  • very high anxiety had extremely accurate recall which contradicts the U hypothesis
• A03


  Supporting evidence

  • Kohnken et al
  • meta analysis of 55 studies compared CIT to standard police interviews
  • found CIT had more detail
  • recall was on average 41% better

  
  

  HOWEVER there was also an increase in amount of inaccurate data recalled which suggests that CI sacrificies quality, e.g. accuracy over quantity, which is detail, thus implying that the EWT must be treated with caution.
• A03


  Limitation

  
  

  One limitation of the cognitive interview technique is that not all of its elements are equally effective and useful Milne and Bull found that each of the techniques used alone produced more information than a standard police interview but they also found that using a combination of reporting everything and reinstating the context produced better recall than any of the other elements or combination of them, thus conforming the police’s suspicions that some aspects of the CI are more useful than others, which casts doubt on the overall credibility of the CIT.
• A03


  Practical problem- police have found that a change of perspective is time consuming and so do not use it in less serious crimes

  • change of perspective is difficult to apply to young children
• A03


  Value

  • social benefits for society
  • incorporated into police interviews had let to a better recall of crimes and reduction in the number of false convictions