Confidence ratings during old-new recognition memory tasks are thought to index the strength of memory evidence elicited by test probes. However, various subject-specific factors may also influence reported confidence, including perceived self-efficacy and idiosyncratic interpretation of the confidence scale. To measure the contribution of subject-specific variables to confidence ratings, we performed regression analyses on extant data from three recognition experiments encompassing procedural variations in encoding and stimuli, testing the degree to which the person making the judgment (the "subject" factor), versus whether or not the judgment is accurate, influences reported confidence. Overall, confidence was less linked to changes in accuracy, for "new" than for "old" judgments. Critically, the subject factor was at least as predictive of rated confidence as accuracy for "old" judgments, whereas for "new" judgments the subject factor was substantially more predictive of confidence than accuracy. These results suggest that measured confidence is largely a function of who is making the rating, especially when items are identified as "new." This suggests that the utility of confidence in predicting memory accuracy will be limited when stable estimates of subject contributions are unavailable, such as when each subject provides one or a few responses.
Keywords: Confidence; Individual differences; Recognition memory.