P3b does not reflect perceived contrasts

Abstract

It has been shown that P3b is not a signature of perceptual awareness per se but is instead more closely associated with post-perceptual processing (Cohen et al., 2020). Here we seek to investigate whether human participants’ attentional states are different in the report and the no-report conditions. This difference in attentional states, if exists, may lead to degraded consciousness of the stimuli in the no-report condition, and it therefore remains unknown whether the disappearance of P3b is due to a lack of reportability or degraded consciousness. Results of our experiment 1 showed that participants did experience degraded contents of consciousness in the no-report condition. However, results of experiment 2 showed that the degraded contents of consciousness did not influence the amplitude of P3b. These findings strengthen the claim that P3b is not a signature of perceptual awareness but is associated with post-perceptual processing.

Significance Statement

P3b, one of the most studied event-related potentials, has been claimed to reflect several cognitive activities, including consciousness. Although recent experiments with the new no-report paradigms suggest otherwise that P3b may not reflect human conscious activities, these results are not yet conclusive. In this study, we conducted a series of modified no-report paradigm experiments, and found that P3b was not modulated by the degrees of conscious perception of stimuli. These results support the claims that P3b may not be a neural marker of consciousness.