Strategy shifts in classification skill acquisition: does memory retrieval dominate rule use?

In two experiments, we demonstrated two types of strategies (rule-based and memory-based) and strategy transitions within the same binary classification task. The strategy that dominated later in practice depended on the difficulty of the operative classification rule and on the salience of the cue for that rule. Accuracy increased over practice trials, and response times were faster for the dominant strategy, either rule or memory. Rule retention was superior to stimulus item retention, so that, even for participants who preferred a memory-based strategy, a rule-based strategy dominated at least temporarily after a 1-week interval. Strategy use over trials and the retention interval reflected a given task's affordance of a shift between rule- and memory-based processes.