Confidence reports during perceptual decision-making do not uniquely reflect subjective experience. Across two experiments with 204 participants and three bias manipulations, non-perceptual factors such as changes in stimulus base rates or asymmetric payoff matrices leaked into confidence judgments. This shows that confidence can be influenced by response biases unrelated to actual perception, complicating its use as a pure measure of subjective experience. The relative strength of biases in first-order choices versus confidence may help distinguish whether a manipulation truly alters perception or only affects decision strategy.
A key challenge in consciousness research is separating genuine conscious perception from non-perceptual biases when observers report whether they saw a stimulus. In experiments with 505 participants who detected and reproduced dim or absent visual patterns under different conditions—attentional cues, asymmetrical base rates, and payoff schemes—a Hurdle-Gaussian model decomposed responses into a perceptual continuous component and a non-perceptual hurdle component. Statistical priors and reward structures shifted the non-perceptual hurdle, while attentional cues selectively shifted the perceptual component, consistent with changes in conscious experience. Crucially, including detection trials contaminated reproduction reports with non-perceptual criterion effects, urging caution in interpreting detection-based measures in consciousness research.