Confidence and decision type under matched stimulus conditions: Overconfidence in perceptual but not conceptual decisions

Within the domain of metacognition, there is disagreement whether different processes underlie evaluations of confidence in perceptual versus conceptual decisions. The relationship between confidence and accuracy for perceptual and conceptual decisions was compared using newly created stimuli that could be used to elicit either decision type. Based on theories of Brunswikian and Thurstonian uncertainties, significant underconfidence for perceptual decisions and overconfidence for conceptual decisions were predicted. Three within-subjects experiments did not support this hypothesis. Participants showed significant overconfidence for perceptual decisions and no over-confidence for conceptual decisions. In addition, significant hard-easy effects were consistently found for both decision types. Incorporating our findings with past results reveals that both over- and underconfidence are attainable on perceptual tasks. This conclusion, in addition to the common presence of hard-easy effects and significant across-task correlations in over/underconfidence, suggests that confidence judgments for the two decision types may depend on largely shared processes. Possible contributions to confidence and over/underconfidence are explored, focusing on response time factors and participants' knowledge bases.