Epstein, M. L. | bioRxiv Science

bioRxiv2025

Perceptual Support for Temporal Normalization Across Hundreds of Milliseconds

Perception across time is limited: phenomena like masking and temporal crowding reveal perceptual interference between sequential stimuli, even when separated by hundreds of milliseconds. However the underlying causes of these suppressive temporal interactions remain unclear. A potential explanatory mechanism is temporal normalization, a form of divisive suppression proposed to operate across time in the visual cortex, but largely untested behaviorally. Here in three experiments we tested a key perceptual prediction of temporal normalization: contrast-dependent suppression between sequential stimuli. By independently manipulating the contrasts of two sequential gratings presented 250 ms apart, we found that perceptual sensitivity to a targets orientation decreased when a high-vs. low-contrast non-target appeared either before or after it. Reduced sensitivity arose from both decreased orientation precision and increased "swapping" errors. The results provide perceptual support for a temporal normalization computation operating across hundreds of milliseconds, offering a theoretical framework for perceptual limits across time. Public significance statementTemporal context strongly affects perception, but a general theoretical framework that captures such effects is lacking. Neural studies support the existence of temporal normalization, the divisive suppression of information across time. However the behavioral impact of temporal normalization on perception remains unclear. Here we tested a key behavioral prediction of temporal normalization: contrast-dependant suppression between sequential stimuli. We found evidence for such suppression across hundreds of milliseconds both forward and backward in time. Our results provide perceptual evidence for temporal normalization, linking neural data to behavior, and support a theoretical framework that could bridge a range of temporal phenomena such as visual masking, adaptation, and temporal crowding.

neuroscience↗

bioRxiv2025

Attention robustly dissociates objective performance and subjective visibility reports

Visual experience can sometimes depart from visual performance, providing a powerful lens into the mechanisms generating conscious perception. In one proposed dissociation--subjective inflation--unattended locations in the periphery appear stronger than attended ones despite equated performance. Subjective inflation has played a central role in motivating theories of consciousness that reject the sufficiency of sensory signals for conscious perception. Yet the empirical basis for subjective inflation is limited. Here, in a large-scale adversarial collaboration, we conducted four simultaneously-replicated experiments testing the strength, character, and extent of subjective inflation under inattention. We used a new analytic approach to quantify inattentional inflation over full psychometric functions, beyond single matched-performance levels. We found robust inattentional inflation for contrast-dependent and texture-based perception, at and above the visual threshold. However at suprathreshold, we found inattentional inflation for the overall stimulus but not the specific feature relevant for performance. Finally, we establish the unifying principle that inattentional inflation occurs if and only if attention reduces performance thresholds more than visibility thresholds. Thus what we think we see may regularly exceed what we can visually discriminate, placing constraints on theories of conscious perception.

neuroscience↗