Analogy has traditionally been defined by use of a contrast definition: analogies represent associations or connections between things distinct from the 'normal' associations or connections determined by our 'ordinary' concepts and categories. Research into analogy, however, is also distinct from research into concepts and categories in terms of the richness of its process models. A number of detailed, plausible models of the analogical process exist (Forbus, Centner and Law, 1995; Holyoak and Thagard, 1995): the same cannot be said of categorisation. In this paper we argue that in the absence of an acceptable account of categorisation, this contrast definition amounts to little more than a convenient fiction which, whilst useful in constraining the scope of cognitive investigations, confuses the relationship between analogy and categorisation, and prevents models of these processes from informing one another. We present a study which addresses directly the question of whether analogy can be distinguished from categorisation by contrasting categorisational and analogical processes, and following from this, whether theories of analogy, notably Centner's structure mapping theory (Centner, 1983; Forbus et al, ibid.), can also be used to model parts of the categorisation process.

Ramscar & Pain (1996) argued that the analogical process cannot be easily distinguished from the categorisation process at a cognitive level. In light of the absence of any distinction between analogy and categorisation, we have argued that analogy is supervenient upon an important part of the classification process, and that as such 'analogical' models are capable of illuminating some categorisation tasks, for instance, the way in which structural systematicity can detennine not only analogical judgements, but also category decisions. Our scepticism regarding the cognitive distinction between these two processes has implications for both analogy and categorisation research: in this paper we consider two leading analogical theories. Centner's Structure Mapping Theory and Holyoak's Multi-Constraint Theory, and argue that results from our use of analogical modeling techniques in categorisation tasks offer some important insights into exactly which elements should be included in a theory of analogical mapping.

We argue that the key question in conceptual storage is best viewed not as a question of instances versus generalisations, but rather one of unitary versus multiple representation accounts of conceptual storage. On previous evidence, it has been difficult to determine whether a particular result stems from stored information regarding the concept or from the processes that operate in invoking a particular concept (Komatsu, 1992). In this paper, we attempt to shed some light on the nature of stored conceptual structure using the different influences that surface and stmctural features have been shown to have on the recall of a particular representation (Centner, Ratterman and Forbus, 1993). We conclude that at least some concepts may not be stored using a unitary representation.