title: Seeing more clearly through psychosis: Depth inversion illusions are normal in bipolar disorder but reduced in schizophrenia.
abstract: Schizophrenia patients with more positive symptoms are less susceptible to depth inversion illusions (DIIs) in which concave objects appear as convex. It remains unclear, however, the extent to which this perceptual advantage uniquely characterizes the schizophrenia phenotype. To address the foregoing, we compared 30 bipolar disorder patients to a previously published sample of healthy controls (N=25) and schizophrenia patients (N=30). The task in all cases was to judge the apparent convexity of physically concave faces and scenes. Half of the concave objects were painted with realistic texture to enhance the convexity illusion and the remaining objects were untextured to reduce the illusion. Subjects viewed objects stereoscopically or via monocular motion parallax depth cues. For each group, DIIs were stronger with texture than without, and weaker with stereoscopic information than without, indicating a uniformly normal response to stimulus alterations across groups. Bipolar patients experienced DIIs more frequently than schizophrenia patients but as commonly as controls, irrespective of the face/scene category, texture, or viewing condition (motion/stereo). More severe positive and disorganized symptoms predicted reduced DIIs for schizophrenia patients and across all patients. These results suggest that people with schizophrenia, but not bipolar disorder, more accurately perceive object depth structure. Psychotic symptoms-or their accompanying neural dysfunction-may primarily drive the effect presumably through eroding the visual system's generalized tendency to construe unusual or ambiguous surfaces as convex. Because such symptoms are by definition more common in schizophrenia, DIIs are at once state-sensitive and diagnostically specific, offering a potential biomarker for the presence of acute psychosis.
authors.affiliation: University Behavioral Health Care, Rutgers University, Piscataway, NJ 08854, USA; Department of Psychiatry, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ 08854, USA; Center for Cognitive Science, Rutgers University, Piscataway, NJ 08854, USA. Electronic address: brian.keane@rutgers.edu.
authors.forename: Brian P
authors.initials: BP
authors.lastname: Keane
authors.affiliation: University Behavioral Health Care, Rutgers University, Piscataway, NJ 08854, USA; Department of Psychiatry, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ 08854, USA.
authors.forename: Steven M
authors.initials: SM
authors.lastname: Silverstein
authors.affiliation: University Behavioral Health Care, Rutgers University, Piscataway, NJ 08854, USA.
authors.forename: Yushi
authors.initials: Y
authors.lastname: Wang
authors.affiliation: University Behavioral Health Care, Rutgers University, Piscataway, NJ 08854, USA.
authors.forename: Matthew W
authors.initials: MW
authors.lastname: Roché
authors.affiliation: Center for Cognitive Science, Rutgers University, Piscataway, NJ 08854, USA; Department of Biomedical Engineering, Rutgers University, Piscataway, NJ 08854, USA.
authors.forename: Thomas V
authors.initials: TV
authors.lastname: Papathomas
mesh_terms: D000328:Adult; D001714:Bipolar Disorder / Q000188:drug therapy / Q000523:psychology*; D003071:Cognition; D003867:Depth Perception; D005260:Female; D006801:Humans; D007088:Illusions; D008297:Male; D008875:Middle Aged; D009039:Motion Perception; D011569:Psychiatric Status Rating Scales; D011618:Psychotic Disorders / Q000188:drug therapy / Q000523:psychology; D012559:Schizophrenia / Q000188:drug therapy; D012565:Schizophrenic Psychology
keywords: Binocular depth inversion; Bipolar disorder; Disorganized symptoms; Hollow mask illusion; Positive symptoms; Prediction-error monitoring