Abstract
It has been assumed that confidence and perceptual judgments access the same information based on the positive correlation between confidence and judgment accuracy (CA correlation). Here, we investigated whether confidence and perceptual judgments were based on the same internal representations of stimuli. We manipulated an orientation similarity using a set of 10 oriented bars. Among them, one bar had a salient orientation (orientation difference from the closest orientation: 55°) and the other bars had similar orientations (orientation difference from the closest orientation: 5°). After a brief presentation of the stimuli, observers adjusted a probe bar to report the target orientation designated by a cue and then drew their confidence ranges in clockwise and counterclockwise directions separately from the reported orientation. We expected that orientation judgments would reflect the categorical representations of orientations: an outlier orientation and an ensemble of similar orientations. Observers’ bias in target responses confirmed this prediction. Similar orientations were biased toward their mean, whereas bias of the outlier orientation did not follow this trend, suggesting the formation of two categories. However, all orientations were biased toward the mean of all orientations in confidence bias (relative difference in the confidence ranges between clockwise and counterclockwise directions), suggesting the formation of one category. Furthermore, the salient orientation was precisely represented without much perceptual bias, but its confidence bias was quite significant. These results suggest that perceptual judgments and confidence are based on different representations of presented orientations. Nevertheless, trial level correlations between absolute objective errors and subjective uncertainty were consistently observed for all reported orientations. These results suggest that the CA correlation cannot be simply regarded as a direct evaluation of actual objective errors using the same information of perceptual judgments. The CA correlation can be significant even with different internal representations between confidence and perceptual judgments.
Acknowledgement: This work was supported by National Research Foundation of Korea (NRF) grant funded by the Korean government (MSIT) (NRF-2016R1A2B4016171).