Unitization during category learning

Five experiments explored the question of whether new perceptual units can be developed if they are useful for a category learning task, and if so, wh at the constraints on this unitization process are. During category learnin g, participants were required to attend either a single component or a conj unction of 5 components. Consistent with unitization, the conjunctive task became much easier with practice; this improvement was not found for the si ngle-component task or for conjunctive tasks in which the components could not be unitized. Influences of component organization (Experiment 1), compo nent contiguity (Experiment 2), component proximity (Experiment 3), and num ber of components (Experiment 4) on practice effects were found. Deconvolve d response times (Experiment 5) showed that prolonged practice yielded fast er responses than predicted by an analytic model that integrates evidence f rom independently perceived components.