Proceedings of the Annual Meeting of the Cognitive Science Society

Two cue validity models for category learning were compared to the exemplar model of Medin & Schaffer (1978). The cue validity models tested for the use of two cue validity measures from the Competition Model of Bates & MacWhinney (1982, 1987, 1989) ("reUabiUty" and "overall validity"); one of these models additionally tested for "rote" associations between items and categories. Twenty-four undergraduate subjects learned to classify pseudowords into two categories over 40 blocks of trials. The overall fit of the cue validity model without rote associations was poor, but the fit of the model that included these was nearly identical to the exemplar model {R^ = .89 V3 .90). However, both cue validity models failed to capture differences predicted by exemplar similarity, but not cue validity, that were apparent as early as the first block of learning trials. The critical parameters in the Medin-SchaiFer model were fit as a logarithmic function of the learning block to provide a uniform account of learning across the 40 blocks of trials. The evidence that we provide suggests that competition at the level of exemplars should be considered as a possible extension of the Competition Model.