The Cognitive Interview: Effects on the realism in witnesses’ confidence in their free recall

Abstract

This study compared the realism of witnesses’ confidence judgments of their own recall elicited in either the Cognitive Interview (CI) or the Structured Interview (SI). Calibration methodology was used to analyse the realism of the confidence judgments. Participants (N=56) were interviewed about their observations of a staged crime and returned 2 weeks later to assess their confidence in the statements. The CI, as in previous research, rendered a significantly higher number of correct recalled units compared with the SI. In both interview conditions the witnesses displayed a high level of accuracy and confidence. In addition, a very good level of calibration and very low overconfidence was found in the witnesses’ confidence judgments. No difference was found between the CI and SI in terms of the realism of the witnesses’ confidence judgments, as measured by level of calibration or under/overconfidence. Furthermore, the CI and the SI did not differ with respect to the witnesses’ estimations of the total number of correctly recalled items. It is suggested that the good realism found in these measures is due to the fact that witnesses assessed their confidence in items they had chosen to report of their own accord.

Keywords:

• Realism in confidence
• calibration
• Cognitive Interview
• confidence–accuracy relation
• Structured Interview

Parts of this research were presented at the 12th European Conference of Psychology and Law, Edinburgh, UK, July 2003. This study was supported by a grant from the Bank of Sweden Tercentenary Foundation given to the first author. We thank Lina Bengtsson, Lina Leander and Fredrik Good for their help in collecting and coding the data.

Notes

1 The original CI consists of two instructions (“reverse-order recall” and “change perspective”) in addition to those used in the present study. These were left out because only the “mental-reinstatement-of-context” and the “report-everything” instructions were expected, on theoretical grounds (Gwyer & Clifford, 1997), to influence witnesses’ confidence, which is the focal issue in the present study. In addition, it is particularly the included components that have been found to be effective in increasing the amount of information elicited in witness interviews (see e.g. Milne & Bull, 2002).

2 The computation of calibration measures required dichotomous accuracy scores for each unit. Thus, more fine-grained scoring typically used in research on the CI, such as distinguishing between confabulations and other incorrect information, was not appropriate for the present purposes. This limitation is arguably of little consequence, however, as previous research shows that the frequency of confabulations is not affected by the use of the CI (see e.g. McCauley & Fisher, 1996; Memon, Cronin, Eaves & Bull, 1993).