Abstract
Perceptual confidence refers to our ability to estimate the validity of our perceptual decision. There is robust evidence that observers have access to a reliable estimate of their own uncertainty when making perceptual decisions. However, so far, evidence is still scarce whether metaperception qualifies as a common mechanism that can monitor decisions across different sensory modalities. In previous work, it has been suggested that perceptual confidence can be evaluated on an abstract scale that is not only task-independent, but also modality-independent. We aimed to scrutinize these findings by measuring visual contrast and tactile vibration discrimination thresholds in a confidence forced-choice task. A total of 26 participants were involved in our study. We determined thresholds for trials in which perceptual judgments were chosen as confident and for those that were declined as confident. Confidence comparisons were made between perceptual decisions either within the visual and tactile modality, respectively, or across both modalities. Furthermore, we assessed executive functions in order to explore a possible link between cognitive control and metaperceptual capacities. We found that perceptual performance was a good predictor of confidence judgments and that the threshold modulation was similarly pronounced in both modalities. Most importantly, participants compared their perceptual confidence across visual and tactile decisions with the same precision as within the same modality. These findings are supported by a Bayesian Repeated Measures ANOVA favouring the null model as the best fitting model. However, we observed substantial variability of confidence sensitivity and executive functions across our participants. We suggest that individual differences in executive functions might provide a critical resource that determines metaperceptual ability. In conclusion, our findings corroborate that perceptual uncertainty can be accessed on an abstract scale and that it can be used to make confidence judgments across sensory modalities.