UNCORRECTED PROOF ARTICLE IN PRESS 1 Visual object processing in schizophrenia: evidence for 2 an associative agnosic deficit 3 Vania S. Gabrovska a , Keith R. Laws b , Julie Sinclair c , Peter J. McKenna d, * 4 a Neuroscience and Psychiatry Unit, University of Manchester, Stopford Building, Oxford Road, Manchester M13 9PT, UK 5 b Department of Psychology, London Guildhall University, Calcutta House, Old Castle St., London E1 7NT, UK 6 c Department of Psychology, University of Hertfordshire, Hatfield, AL10 9AB, UK 7 d Fulbourn Hospital, Cambridge CB1 5EF, UK 8 9 Received 22 February 2001; accepted 9 January 2002 10 Abstract 11 Early studies suggested visual form perception impairment in schizophrenia. To re-examine this claim and characterise the 12 deficit neuropsychologically, 41 schizophrenic patients were administered tests sensitive to different levels of visual object 13 perception and recognition. Intellectually well-preserved patients were examined separately on these and additional tests. Single 14 case analysis was also applied to four patients showing varying degrees of general intellectual impairment. As a group, the patients 15 showed little impairment on tests of early visual object perception, but greater impairment on higher-level visual processing tests, 16 in particular object recognition and naming. This held true for patients with preserved general intellectual function. Single case 17 analysis suggested that patients with schizophrenia have a selective deficit affecting object recognition and identification, with a 18 pattern similar to visual associative agnosia in neurological patients. D 2002 Published by Elsevier Science B.V. 19 20 Keywords: Visual object; Schizophrenia; Agnosia 21 22 23 1. Introduction 24 Studies of visual perception in schizophrenia were 25 first carried out in the 1950s when, with the influence 26 of Gestalt psychology, authors speculated that halluci- 27 nations and perhaps other symptoms might reflect a 28 complex perceptual disorder (Conrad, 1974; Wecko- 29 wicz, 1957). Reviewing the many studies of this era, 30 Frith (1973) and Cutting (1985) concluded that basic 31 processes such as flicker fusion threshold, sensitivity 32 throughout the visual field and critical stimulus dura- 33 tion remained intact in schizophrenia, but that impair- 34 ment was commonly found on tasks requiring the 35 identification of ambiguous pictures, out-of-focus 36 objects, and embedded figures, as well as on tasks 37 employing standard visual illusions. These findings led 38 Cutting (1985) to conclude that ‘most experiments on 39 form perception have revealed some abnormality’ in 40 schizophrenia. 41 In the years following these studies, there have 42 been advances in the understanding of the normal 43 cognitive processes underlying visual form perception. 44 Based on evidence from normal individuals and neu- 45 rological patients, Marr (1982), Humphreys and Rid- 46 doch (1987), Ellis and Young (1988) and Farah (1990) 47 have proposed models of object perception and rec- 0920-9964/02/$ - see front matter D 2002 Published by Elsevier Science B.V. PII:S0920-9964(02)00168-8 * Corresponding author. E-mail address: peter.mckenna@virgin.net (P.J. McKenna). www.elsevier.com/locate/schres Schizophrenia Research 1705 (2002) xxx – xxx