Nicolás Sánchez-Fuenzalida

A central challenge in consciousness research is determining whether observers have a conscious experience of a stimulus. However, present/absent detection judgments are often biased by contextual factors, making it difficult to isolate conscious perception from non-perceptual influences. Traditional psychophysical methods struggle to disentangle these components. To address this, we conducted in-person experiments (N\,= 505) in which participants detected and reproduced dim and absent contrast-defined Gabor stimuli under three contextual manipulations: attentional cues, asymmetrical base rates, and payoff schemes. Using a reproduction task together with a Hurdle-Gaussian model, we quantitatively decomposed reproduction responses into a perceptual continuous contrast component and a non-perceptual “hurdle” component. We found that statistical priors (base rate) and reward structures (payoff) induced non-perceptual shifts in the reproduction hurdle, whereas attentional cues selectively shifted the continuous contrast component, consistent with changes in conscious experience. Critically, comparing conditions with and without intermixed detection trials revealed that the presence of a detection task contaminates reproduction reports with non-perceptual criterion effects. This highlights the need for caution in using and interpreting results that rely on detection judgments, even when combined with subjective measures like reproduction, especially given the central role that detection tasks play in consciousness research.

In noisy perceptual environments, people frequently make decisions based on non-perceptual information to maximize rewards. Therefore, a central problem in psychophysics, metacognition and consciousness research is to distinguish between decisions resulting from changes in subjective experience and those arising from non-perceptual information. It has recently been proposed that confidence reports can be used to discriminate between changes in subjective experience and those arising from non-perceptual information. Here we use a Bayesian ordinal modelling framework combined with an explicit measure of subjective experience to show across two experiments (N = 204) and three bias manipulations that confidence during perceptual decision-making does not uniquely reflect subjective experience. Instead, non-perceptual manipulations affecting response bias leak into perceptual confidence reports. This occurs not only for biases resulting from changes in the base rate of stimuli (cognitive priors), but also when biasing information does not inform decision correctness (asymmetric payoff matrix). The relative strength of biases in first-order responses and confidence may help disentangle whether a given bias manipulation is perceptual in nature or not.

To survive, organisms constantly make decisions to avoid danger and maximize rewards in information-rich environments. As a result, decisions about sensory input are not only driven by sensory information but also by other factors, such as the expected rewards of a decision (known as the payoff matrix) or by information about temporal regularities in the environment (known as cognitive priors or predictions). However, it is unknown to what extent these different types of information affect subjective experience or whether they merely result in nonperceptual response criterion shifts. To investigate this question, we used three carefully matched manipulations that typically result in behavioral shifts in decision criteria: a visual illusion (Muller-Lyer condition), a punishment scheme (payoff condition), and a change in the ratio of relevant stimuli (base rate condition). To gauge shifts in subjective experience, we introduce a task in which participants not only make decisions about what they have just seen but are also asked to reproduce their experience of a target stimulus. Using Bayesian ordinal modeling, we show that each of these three manipulations affects the decision criterion as intended but that the visual illusion uniquely affects sensory experience as measured by reproduction. In a series of follow-up experiments, we use computational modeling to show that although the visual illusion results in a distinct drift-diffusion (DDM) parameter profile relative to nonsensory manipulations, reliance on DDM parameter estimates alone is not sufficient to ascertain whether a given manipulation is perceptual or nonperceptual.