Negative affect impedes perceptual filling-in in the uniformity illusion

The notion of cognitive penetrability, i.e., whether perceptual contents can in principle be influenced by non-perceptual factors, has sparked a significant debate over methodological concerns and the correct interpretation of existing findings. In this study, we combined predictive processing models of visual perception and affective states to investigate influences of affective valence on perceptual filling-in in extrafoveal vision. We tested how experimentally induced affect would influence the probability of perceptual filling-in occurring in the uniformity illusion (N = 50). Negative affect led to reduced occurrence rates and increased onset times of visual uniformity. This effect was selectively observed in illusionary trials, requiring perceptual filling-in, and not in control trials, where uniformity was the veridical percept, ruling out biased motor responses or deliberate judgments as confounding variables. This suggests an influential role of affective status on subsequent perceptual processing, specifically on how much weight is ascribed to priors as opposed to sensory evidence.