Dissociating effects on encoding versus access in visual masking

• Applicant: Professor Dr. John-Dylan Haynes
• Subject Area: General, Cognitive and Mathematical Psychology
• Term: from 2008 to 2011
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 60167411

Two complementary processes play a role in regulating whether a visual stimulus reaches a person's awareness. First, the stimulus has to be encoded in the visual system. Second, the brain has to provide access to a representation of the stimulus in visual cortex. Currently it is unclear which brain processes mediate encoding and access respectively. Importantly, the distinction between representation or encoding and access does not follow a simple distinction between visual and prefrontal cortical regions. This is because visual brain regions take place in regulating access (for example via attentional functions in V4), and prefrontal regions can take part in encoding of stimuli. Here we propose a project that will investigate the cortical mechanisms of encoding and access using an information-theoretic framework based on multivariate decoding in combination with fMRI. We will investigate how graded transitions between visible and invisible stimuli under different forms of masking lead to changes in the encoding of stimulus features in visual brain regions, but also in regions outside the traditional visual system including prefrontal cortex. This will help reveal to which degree brain regions that are modulated by visual awareness are indeed involved in encoding of specific stimulus features.

• DFG Programme: Research Grants