Evaluation

• Support for the effectiveness of the CI


  One strength of the cognitive interview is evidence that it works:

  • For example, a meta-analysis by Gunter Kohnken et al. (1999) combined data from 55 studies comparing the CI with standard police interviews
  • The CI gave an average 41% increase in accurate information compared with the standard interview. Only 4 studies showed no difference
  • This shows that the CI is an effective technique in helping witnesses to recall information that is stored in memory but not immediately accessible
• Counterpoint of support for the effectiveness of the CI


  Kohnken et al. also found an increase in the amount of inaccurate information recalled by participants. This was a particular issue in the ECI, which produced more incorrect details than the CI. Cognitive interviews may sacrifice quality of EWT in favour of quantity. This means that police officers should treat eyewitness evidence from CIs/ECIs with caution.
• Some elements may be more useful than others

  One limitation of the original CI is that not all of its elements are equally effective or useful:

  • Rebecca Milne and Ray Bull (2002) found that each of the four techniques used alone produced more information than the standard police interview.
  • But they also found that using a combination of report everything and reinstate context produced better recall than any other combination
  • This confirmed police officers' suspicions that some aspects of the CI are more useful than others
  • This casts some doubt on the credibility of the overall CI
• The CI is time-consuming


  One limitation of the CI is that police officers may be reluctant to use the CI because it takes more time and training than standard police interviews:

  • For example, more time is needed to establish rapport with witnesses and allow them to relax. The CI also requires special training and many forces do not have the resources to provide more than a few hours
  • This suggests that the complete CI as it exists is not a realistic method for police officers to use and it might just be better to focus on a few elements