Altered perception of apparent motion in schizophrenia spectrum disorder Wolfgang Tschacher a, ⁎ , Priscilla Dubouloz b , Rahel Meier b , Uli Junghan a a University Hospital of Psychiatry, University of Bern, Laupenstrasse 49, CH-3010 Bern, Switzerland b University Hospital (Inselspital), University of Bern, Murtenstrasse 35, 3010 Bern, Switzerland Received 24 May 2006; received in revised form 20 November 2006; accepted 7 April 2007 Abstract Apparent motion (AM), the Gestalt perception of motion in the absence of physical motion, was used to study perceptual organization and neurocognitive binding in schizophrenia. Associations between AM perception and psychopathology as well as meaningful subgroups were sought. Circular and stroboscopic AM stimuli were presented to 68 schizophrenia spectrum patients and healthy participants. Psychopathology was measured using the Positive and Negative Syndrome Scale (PANSS). Psychopathology was related to AM perception differentially: Positive and disorganization symptoms were linked to reduced gestalt stability; negative symptoms, excitement and depression had opposite regression weights. Dimensions of psychopathology thus have opposing effects on gestalt perception. It was generally found that AM perception was closely associated with psychopathology. No difference existed between patients and controls, but two latent classes were found. Class A members who had low levels of AM stability made up the majority of inpatients and control subjects; such participants were generally young and male, with short reaction times. Class B typically contained outpatients and some control subjects; participants in class B were older and showed longer reaction times. Hence AM perceptual dysfunctions are not specific for schizophrenia, yet AM may be a promising stage marker. © 2007 Elsevier Ireland Ltd. All rights reserved. Keywords: Diagnostic marker; Gestalt perception; Neurocognition; Perceptual organization; Psychopathology; Schizophrenia 1. Introduction Apparent motion (AM) is the perception of motion when physical motion of the stimuli presented is absent. A familiar example of AM is the stroboscopic effect used in cinematography. Although only a rapid succession of stills is displayed on the screen, smooth, uninterrupted motion (a “movie”) is seen. Gestalt theory posited AM as a demonstration of the holistic aspects of perception (“phi phenomenon” in Wertheimer, 1912). The simplest paradigm that evokes AM consists in presenting a stimulus, e.g. a black disk, alternately in positions A and B of the visual field. Over a wide range of interstimulus intervals and frequencies of flashing, the viewer perceives the stimulus wandering back and forth between A and B. Clearly, the perceptual quality of movement is actively added to the physical stimuli by the viewer's information-processing system. AM repre- sents the constructive properties of perception, together with further phenomena of perceptual organization, such as perceptual grouping and figure-ground discrim- ination. AM phenomena are thus not only prerequisite to being able to watch movies, but are also ecologically Available online at www.sciencedirect.com Psychiatry Research 159 (2008) 290 – 299 www.elsevier.com/locate/psychres ⁎ Corresponding author. Tel.: +41 31 3876111; fax: +41 31 3829020. E-mail address: tschacher@spk.unibe.ch (W. Tschacher). 0165-1781/$ - see front matter © 2007 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.psychres.2007.04.005