General markers of conscious visual perception and their timing

TL;DR

This study identifies N200 and P300 as reliable neural markers of conscious visual perception, with onset around 200 ms, but their timing varies due to amplitude fluctuations and noise, explaining discrepancies in prior research.

Contribution

It demonstrates that N200 and P300 are consistent markers of conscious perception across various stimuli, clarifying their onset timing and variability.

Findings

N200 and P300 are reliable markers of conscious perception.

Onset latency is around 200 ms but varies across data subsets.

Amplitude fluctuations influence marker latency variability.

Abstract

The goal of the present investigation was to identify reliable markers of conscious visual perception and to characterize their onset latency and its variability. To that end many visual stimuli from different categories were presented at near-threshold contrast and contrastive analyses were carried out on 100 balanced subsets of the data. N200 and P300 were the two reliable markers of conscious perception common to all perceived stimuli and absent for all nonperceived stimuli. The estimated mean onset latency for both markers was shortly after 200 ms. However, the onset latency of both of these markers of conscious perception showed considerable variability depending on which subsets of the data were considered. Some of this variability could be attributed to noise, but it was first and foremost the amplitude fluctuation in the condition without conscious perception that explained the variability in onset latencies of the markers of conscious perception. The present results help to understand why different studies have observed different onset times for the neural correlates of conscious perception. Moreover, the consciousness markers explored here have more generality as stimulus specificity was reduced.