Visual Perception Disturbances in Schizophrenia: A Unified Model.

Despite demonstrations of perceptual impairments in schizophrenia as far back as Kraepelin ( 1903 ), and although the visual system is the most understood area of cognitive neuroscience, there has been much less work focused on vision in schizophrenia compared to other domains (e.g., memory, executive function) (Silverstein & Keane, 2011b ). This, despite an ever increasing body of literature indicating that visual impairments are prevalent among individuals with schizophrenia, and that they are important in terms of understanding the nature of the condition and its course. For example, approximately 25–30 % of individuals with schizophrenia report visual hallucinations (Waters et al., 2014 ), and the rate of patients reporting visual distortions (in the domains of brightness, motion, form, and color) is at least double that (Cutting & Dunne, 1986 ; Phillipson & Harris, 1985 ). Laboratory measures of these domains of visual processing have long track records in experimental psychology, and have provided many demonstrations of impairments in schizophrenia research (reviewed below). Importantly, visual abnormalities are clinically signifi cant. For example, visual distortions are associated with suicidal ideation even after controlling for factors such as psychotic symptoms and auditory distortions (Grano et al., 2015 ). Laboratory indices of visual impairments are related to impaired cognition (Calderone, Hoptman, et al., 2013 ; Haenschel et al., 2007 ), and social cognition (Butler et al., 2009 ; Green, Hellemann, Horan, Lee, & Wynn, 2012 ; Kim et al., 2010 ; Kim, Shim,