Rule use in character classification: Are serial and parallel processing discrete?

Contrary to predictions of a stochastic self-terminating search model, choice reaction times were lower for rulebound positive sets than for nonrulebound positive sets when memory set sizes were varied and stimulus probabilities were held constant. The result suggests that rule use and chunking, as opposed to probability alone, facilitate character classification. As a corollary, it is proposed that serial and parallel processing differ in degree rather than in kind. The extent to which the memory set has been chunked is the critical variable affecting Ss' scanning practices.