Influencing Confidence: Testing Ways to Increase or Decrease Confidence in Knowledge

ABSTRACT This paper examines approaches for influencing people's confidence in their knowledge without influencing knowledge. Three studies examined the relative effectiveness of training and false feedback approaches. Participants chose which of two IKEA products they thought was more expensive and indicated their confidence in that judgment for 50 product pairs. In Study 1, participants took part in one of five conditions designed to manipulate their confidence: false feedback‐increasing, false feedback‐decreasing, training‐increasing, training‐decreasing, or control. For false feedback, we told participants they did very well or poorly on the task. For training‐increasing, we gave participants information about IKEA pricing that appeared useful but was difficult to implement. For training‐decreasing, we developed an automated calibration training technique that provided personalized calibration feedback consisting of a calibration diagram accompanied by textual summary information and advice. Neither the false feedback nor training approach increased confidence on 50 subsequent knowledge‐confidence judgments. However, both manipulations designed to reduce confidence were successful, with a substantially larger effect in the calibration training condition. In Study 2, we adapted the calibration training approach to provide false feedback indicating participants were either underconfident or overconfident. Both the original calibration training pproach and the new false feedback approach indicating overconfidence reduced confidence, and the false feedback approach indicating underconfidence increased confidence. Study 3 tested the effectiveness of this new false feedback approach on an on‐line rather than student sample, finding essentially the same results as those in Study 2. Throughout the three studies, the effects of the manipulations extended to overconfidence, overall calibration, and the Brier score. The results provide a potential tool for research and practice regarding confidence in knowledge.