title: Encoding of configural regularity in the human visual system.
abstract: The visual system is very efficient in encoding stimulus properties by utilizing available regularities in the inputs. To explore the underlying encoding strategies during visual information processing, we presented participants with two-line configurations that varied in the amount of configural regularity (or degrees of freedom in the relative positioning of the two lines) in a fMRI experiment. Configural regularity ranged from a generic configuration to stimuli resembling an "L" (i.e., a right-angle L-junction), a "T" (i.e., a right-angle midpoint T-junction), or a "+",-the latter being the most regular stimulus. We found that the response strength in the shape-selective lateral occipital area was consistently lower for a higher degree of regularity in the stimuli. In the second experiment, using multivoxel pattern analysis, we further show that regularity is encoded in terms of the fMRI signal strength but not in the distributed pattern of responses. Finally, we found that the results of these experiments could not be accounted for by low-level stimulus properties and are distinct from norm-based encoding. Our results suggest that regularity plays an important role in stimulus encoding in the ventral visual processing stream.
authors.affiliation: Laboratories of Biological and Experimental Psychology, KU Leuven, Leuven, Belgium.
authors.forename: Jonas
authors.initials: J
authors.lastname: Kubilius
authors.affiliation: Laboratory of Experimental Psychology, KU Leuven, Leuven, Belgium.
authors.forename: Johan
authors.initials: J
authors.lastname: Wagemans
authors.affiliation: Laboratory of Biological Psychology, KU Leuven, Leuven, Belgium.
authors.forename: Hans P
authors.initials: HP
authors.lastname: Op de Beeck
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D010364:Pattern Recognition, Visual / Q000502:physiology*; D014793:Visual Cortex / Q000502:physiology*; D014795:Visual Pathways / Q000502:physiology*; D055815:Young Adult
keywords: encoding; fMRI; grouping; perceptual organization; regularity