Visual information can be processed by the brain without reaching consciousness. Using multivariate pattern analysis and magnetoencephalography, brain activity was recorded while participants viewed stimuli at threshold contrast in a backward masking paradigm. Both conscious and non-conscious trials contained stimulus information, but the information was enhanced in conscious trials. Visual consciousness is characterized by enhanced neural activity representing the visual stimulus, an effect arising as early as 180 ms post-stimulus onset.
Brain activity carries information about visual stimuli even when people are not consciously aware of them, but conscious awareness is associated with stronger neural representations. Using magneto-encephalography and multivariate pattern analysis, the authors decoded stimulus information from brain recordings while participants viewed stimuli at threshold contrast in a backward masking paradigm. Consciousness was measured with both forced-choice categorization and self-report. Stimulus information was present in brain activity during both conscious and non-conscious trials, but it was enhanced in conscious trials. The enhancement of neural activity characterizing visual consciousness arises as early as 180 milliseconds after stimulus onset.