Is consciousness graded, dichotomous, or both?

Abstract

This study aims to shed light on an ongoing debate in the visual awareness literature: is our conscious experience graded or binary? The Recurrent Processing Hypothesis assumes a graded transition (i.e. a linear relationship between stimulus duration and visibility). The Global Workspace Theory assumes an all-or-none transition (i.e. a non-linear enhancement of visibility once stimulus duration is sufficient). Here we intend to integrate the two theories and their supporting evidence, by controlling for the “level of processing” of the presented stimuli, a factor that was overlooked so far. To this end, we used a masked priming paradigm. Participants expressed either low-level judgements (color naming) or high-level judgements (number categorization) on the very same colored number stimuli. These were presented for 10 ms up to 80 ms. On every trial, participants were also asked to assess the subjective visibility of the stimulus in four steps, by means of the Perceptual Awareness Scale (ranging from “not seen” over “weak glimpse” and “almost clear image” to “clear image”). Non-linear models were fitted to the accuracy and the visibility data, respectively. We predicted and observed a graded access to consciousness in the low-level task, but a dichotomous access in the high-level task. This suggests that the Recurrent Processing Hypothesis and the Global Workspace Theory can be integrated if the level of processing is taken into account. We speculate that a more graded local workspace is sufficient for conscious access in low-level tasks, whereas in high-level tasks this requires an all-or-none global workspace.info:eu-repo/semantics/publishe