Calibrating Confidence

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Science  02 Feb 2007:
Vol. 315, Issue 5812, pp. 574
DOI: 10.1126/science.315.5812.574a

One of the challenges in reasoning by means of a deliberative and conscious process is the weighting of evidence that is reported by other humans. For people sitting as jurors in a trial, this translates into deciding whether to believe what a witness says. Previous studies have demonstrated that confidently uttered statements are believed more often and that being accurate on other issues, even those peripheral to the adjudicated question, is conducive to being believed.

Tenney et al. show an interaction between these parameters in mock trials of civil (car accident) and criminal (burglary) cases. Two witnesses were equally confident in asserting their recollections of how the accident had occurred, yet one was uncertain about other events that had taken place on that day whereas the other professed a complete and accurate recall. Subsequently, both witnesses were shown to have been correct about the weather conditions at the time of the incident, but both were also shown to have been in error in placing a personal appointment (entirely unrelated to the accident) on that same day. Although, as expected, the credibility of the supremely confident witness was rated higher initially, the less confident witness was regarded as being more credible after their fallibility had been revealed. — GJC

Psychol. Sci. 18, 46 (2007).

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