title: Neural correlates of state- and strength-based perception.
abstract: Perceptual judgments can be based on two kinds of information: state-based perception of specific, detailed visual information, or strength-based perception of global or relational information. State-based perception is discrete in the sense that it either occurs or fails, whereas strength-based perception is continuously graded from weak to strong. The functional characteristics of these types of perception have been examined in some detail, but whether state- and strength-based perception are supported by different brain regions has been largely unexplored. A consideration of empirical work and recent theoretical proposals suggests that parietal and occipito-temporal regions may be differentially associated with state- and strength-based signals, respectively. We tested this parietal/occipito-temporal state/strength hypothesis using fMRI and a visual perception task that allows separation of state- and strength-based perception. Participants made same/different judgments on pairs of faces and scenes using a 6-point confidence scale where "6" responses indicated a state of perceiving specific details that had changed, and "1" to "5" responses indicated judgments based on varying strength of relational match/mismatch. Regions in the lateral and medial posterior parietal cortex (supramarginal gyrus, posterior cingulate cortex, and precuneus) were sensitive to state-based perception and were not modulated by varying levels of strength-based perception. In contrast, bilateral fusiform gyrus activation was increased for strength-based "different" responses compared with misses and did not show state-based effects. Finally, the lateral occipital complex showed increased activation for state-based responses and additionally showed graded activation across levels of strength-based perception. These results offer support for a state/strength distinction between parietal and temporal regions, with the lateral occipital complex at the intersection of state- and strength-based processing.
authors.affiliation: University of California, Davis.
authors.forename: Mariam
authors.initials: M
authors.lastname: Aly
authors.forename: Charan
authors.initials: C
authors.lastname: Ranganath
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Yonelinas
mesh_terms: D000328:Adult; D001931:Brain Mapping; D005145:Face; D005260:Female; D006801:Humans; D007600:Judgment / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D009483:Neuropsychological Tests; D009778:Occipital Lobe / Q000502:physiology*; D010296:Parietal Lobe / Q000502:physiology*; D010775:Photic Stimulation; D011930:Reaction Time; D021641:Recognition, Psychology; D013647:Task Performance and Analysis; D013702:Temporal Lobe / Q000502:physiology*; D014796:Visual Perception