Perceptual decisions are typically accompanied by a subjective sense of (un)certainty. There is robust evidence that observers have access to a reliable estimate of their own uncertainty and can judge the validity of their perceptual decisions. However, there is still a debate to what extent these meta-perceptual judgements underly a common mechanism that can monitor perceptual decisions across different sensory modalities. 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 56 participants took part in our study. We determined thresholds for trials in which perceptual decisions 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 to explore a possible link between cognitive control and meta-perceptual 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. Cognitive control capacities were not related to meta-perceptual performance. In conclusion, our findings corroborate that perceptual uncertainty can be accessed on an abstract scale, allowing for confidence comparisons across sensory modalities.

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