Fisher (1988) uses the COBWEB concept formation system to illustrate a computational unification of basic level and typicality effects. The model relies on probabiUstic, distributed concept representations, and appropriate interaction between cue and category validity. W e review this work and report a new account of the fan effect. This extension requires an additional assumption of parallel processing, but otherwise is explained by precisely the same mechemisms as basic level and typicality phenomena.
