Probing the neural geometry of conscious object perception in time

Abstract

Conscious object recognition is a critical brain function, key to making sense of the plethora of visual inputs and guiding adaptive behavior. Yet, the sequence of neural processing underlying conscious object recognition remains unclear. Existing proposals alternatively suggest that conscious object recognition proceeds in a "coarse-to-fine" sequence or a "fine-to-coarse" sequence. Here, we recorded high-density EEG while participants of both sexes performed a threshold-level object recognition task under different viewing conditions. Both superordinate and basic-level category information emerged early in neural activity, followed by a late superordinate category representation in an abstract format that is disentangled from low-level object features. Strikingly, in the early period, while basic-level category information positively correlated with perceptual awareness, superordinate category information negatively predicted perceptual awareness. By contrast, both superordinate and basic-level category information positively correlated with objective categorization accuracy in the early period. In the late period, both levels of category information positively correlated with awareness. These results suggest that neural processing underlying conscious object perception proceeds from the basic to the superordinate category level.