Conditional reasoning and the Tower of Hanoi: The role of spatial and verbal working memory Simon J. Handley*, A. Capon, C. Copp and C. Harper Centre for Thinking and Language, Department of Psychology, University of Plymouth, UK This paper reports a study that investigated the relationships between verbal and spatial measures of working memory capacity and performance on the Tower of Hanoi and a conditional reasoning task. Four working memory measures were included, a simple word span, a simple spatial span, a complex verbal span and a complex spatial span. The participants were 70 undergraduate students. Solution time on the Tower of Hanoi task correlated highly with both measures of spatial memory capacity, but not with the verbal working memory spans. In contrast, logical performance on the conditional reasoning task correlated highly with the complex verbal working memory span, but not with the spatial spans. A conrmatory factor analysis of the data elicited a best-t model comprising a correlated spatial and verbal factor. The results are interpreted in the context of recent work that suggests a dissociation between spatial and verbal resources at the level of the central executive. It is commonly assumed that higher-level cognitive tasks, such as reasoning, problem solving or language comprehension, rely upon a working memory system that enables the simultaneous processing and storage of representations (for a review, see Gilhooly, 1998). Performance on such tasks is held to be constrained by the processing limitations of such a system (for example, Carpenter & Just, 1989; Johnson-Laird & Byrne, 1991; Rips, 1994). The most widely accepted conception of working memory as a storage and processing system is based upon Baddeley and Hitch’s (1974) tripartite model. In this model working memory is composed of three components; a central executive, supported by two slave systems, the phonological loop (PL) and the visuospatial scratchpad (VSSP). The phonological loop and visuospatial scratchpad are thought to be responsible for the rehearsal and passive storage of verbal and visuospatial informa- tion, respectively. The central executive is perceived as a domain general system, responsible for the allocation of attentional resources, the monitoring of information 501 British Journal of Psychology (2002), 93, 501–518 © 2002 The British Psychological Society www.bps.org.uk * Requests for reprints should be addressed to Dr S. J. Handley, Centre for Thinking and Language, Department of Psychology, University of Plymouth, Plymouth, Devon, UK (e-mail: shandley@plymouth.ac.uk).