Knowing where without knowing what: partial awareness and high-level processing in continuous flash suppression
55.14, Tuesday, May 14, 5:15 - 7:15 pm, Royal Ballroom 1-3
Liad Mudrik1, Hagar Gelbard-Sagiv1, Nathan Faivre1, Christof Koch1; 1California Institute of Technology
The scope of unconscious processing has been widely debated. Recently, more evidence for unconscious high-level processing was reported, mainly using continuous flash suppression (CFS). In CFS, Mondrian patches are flashed to the dominant eye while a static object is presented to the other eye. Despite the strong suppression induced, we found it allows prolonged periods of partial awareness: 2-6 seconds before subjects reported seeing the suppressed object, they were able to accurately localize it (at either the right or the left side of the visual field). Critically, when the display was stopped immediately after object localization, subjects were at chance for classifying it as a food or non-food item. In a second experiment, we asked whether such partial awareness could explain some of the previously reported high-level processing during CFS. We suppressed the perception of famous and non-famous faces (primes), presented at either the right or the left visual hemifield for 1.5s. The same or a different face (target) appeared immediately thereafter for 0.7s at the center of the screen, enlarged by 20%. Subjects were first asked to classify the target as famous or not, and then to indicate the primes location and rate their confidence regarding the location on a scale of 1-4. A clear separation between localization and classification was again found, so that in about third of the trials, subjects could localize the face but not classify it. Critically, only at this stage of partial awareness an adaptation effect for the target occurred; no adaptation was found during complete unconscious processing, when subjects could not classify nor localize the prime. As expected, when subjects were able to do both priming was found. Our results call for a better objective measure for awareness, and put former findings of unconscious priming and adaptation in CFS into question.