Visual experience depends on level of processing

Invited talk by Bert Windey, Universite Libre de Bruxelles.

The nature of our visual experience of the world has been examined thoroughly in both philosophy and cognitive psychology, but a number of issues remain the object of hot debates. One such pending issue is whether our visual experience is graded or dichotomous. Considerable evidence has been collected for both views. In a series of experiments, we tested whether the level of processing of the presented stimuli can account for seemingly contradictory results. Participants expressed either low-level judgments (color naming) or high-level judgments (number or word categorization) on the very same stimuli. We obtain both objective performance measures and subjective visibility ratings for different stimulus strengths. We subsequently analyze psychophysical curves, distributions of subjective ratings, and performance for different subjective ratings, and compare the results for low-level versus high-level tasks. Altogether we propose that whether visual experience is graded or dichotomous depends on the level of processing of the stimuli during task execution. This has important implications for theories of consciousness that make claims about the graded vs. dichotomous nature of visual experience, such as global workspace theory.