INTRODUCTION Neuropsychological studies in schizophrenia have emphasized executive function deficits in a variety of hypothetically independent domains including spatial working memory, complex problem solving, planning and inhibition (e.g., Hutton et al., 1998; Mahurin et al., 1998; Weickert et al., 2000; Marczewski et al., 2001). Performance on executive function tests is primarily viewed as reflective of frontal lobe dysfunction, a view that is bolstered by emerging evidence from functional neuroimaging suggesting reduced frontal activation in patients with schizophrenia (Weinberger et al., 1986; Velakoulis and Pantelis, 1996; Callicott et al., 2000; Barch et al., 2001). The presence of similar difficulties on executive function tasks in the nonpsychotic relatives of patients with schizophrenia has also focussed attention on models of neuropsychological function as trait markers of schizophrenia (e.g., Michie et al., 2000; Egan et al., 2001). However, executive function deficits are also present in a number of developmental and neuropsychiatric disorders (Pennington and Ozonoff, 1996). It is feasible, therefore, that the neural systems subserving these cognitive functions are simply the most sensitive to any change in operating conditions and do not provide information regarding aetiologically significant processes specific to schizophrenia. The aim of the current research is to reassess the nature, role and specificity of executive processes associated with schizophrenia. The apparent lack of discriminant validity in executive function tasks may be overcome if it can be demonstrated that in schizophrenia different functional relationships occur within the separable components of executive behaviour. For example, Pantelis et al. (1997) argued that, “there is a loss of the normal relationships between different domains of executive function in schizophrenia” (p. 1823) consistent with abnormalities in fronto-striatal- thalamic circuitry (Robbins, 1990; Frith, 1992; Owen et al., 1992; Pantelis et al., 1997). Pantelis et al. (1997) presented a detailed analysis of the performance of schizophrenia patients on a computerized test battery, [the Cambridge Neuropsychological Test Automated Battery (CANTAB)] that was designed with a significant focus on those functions subserved by fronto-striatal circuitry (Fray et al., 1997). The results were compared to those from a matched sample of Cortex, (2005) 41, 753-763 RESEARCH ARTICLE SPATIAL WORKING MEMORY AND PLANNING ABILITY: CONTRASTS BETWEEN SCHIZOPHRENIA AND BIPOLAR I DISORDER Johanna C. Badcock 1 , Patricia T. Michie 1,2,3 and Danny Rock 1 ( 1 School of Psychiatry and Clinical Neurosciences, University of Western Australia/Centre for Clinical Research in Neuropsychiatry, Graylands Hospital, Perth, Australia; 2 School of Psychology, University of Western Australia; 3 Current address: School of Behavioural Sciences, University of Newcastle, Australia) ABSTRACT Working memory may be conceptualized as a multi-component system involving the active maintenance and manipulation of stored information in the service of planning/guiding behaviour. Impaired spatial working memory is a robust finding in schizophrenia patients which has been related to an impairment in frontostriatal connectivity. The purpose of this study was to examine the specificity of this impairment by comparing the mnemonic and executive aspects of working memory performance in schizophrenia and bipolar disorder with psychotic features, focusing particularly on the functional dynamics between task components. Twenty-four patients with schizophrenia, 14 patients with bipolar I disorder (manic phase) and 33 healthy control subjects were assessed using the Cambridge Neuropsychological Test Automated Battery (CANTAB): including the spatial working memory (between search errors and strategy scores) spatial span (storage capacity) and spatial planning (Stockings of Cambridge: accuracy and latency) tasks. Both patient groups were impaired on the spatial span task, which requires the maintenance and retrieval of stored information. In contrast, only schizophrenia patients showed a significant deficit in between search errors, which requires both maintenance and manipulation of information in working memory. That is, they exhibited both a mnemonic and an executive dysfunction. Spatial span was particularly important to accurate planning ability in bipolar patients. In contrast, in patients with schizophrenia poor spatial working memory was a significant predictor of planning impairments, consistent with failures in goal selection, evaluation and/or execution. Furthermore, initial planning time was positively correlated with the latency to complete a planning sequence. This pattern of slow cognitive processing in schizophrenia patients only, resembled that reported previously in patients with basal ganglia disorders. These findings are discussed in terms of a possible common disturbance in fronto-parietal circuitry in the two disorders together with a specific disturbance of fronto-striatal circuitry in schizophrenia, that is not present in bipolar disorder. Key words: schizophrenia, bipolar I disorder, working memory, planning, frontostriatal circuits