Comparing direct and indirect measures of sequence learning

Comparing the sensitivity of similar direct and indirect measures is proposed as the best way to provide evidence for unconscious learning. The authors apply this approach, first proposed by E. M. Reingold and P. M. Merikle (1988), to a choice reaction-time task in which the material is generated probabilistically on the basis of a finite-state grammar (A. Cleeremans, 1993). The data show that participants can learn about the structure of the stimulus material over training with the choice reaction-time task, but only to a limited extent-a result that is well predicted by the simple recurrent network model of A. Cleeremans and J. L. McClelland (1991). Participants can also use some of this knowledge to perform a subsequent generation task. However, detailed partial correlational analyses that control for knowledge as assessed by the generation task show that large effects of sequence learning are exclusively expressed through reaction time. This result suggests that at least some of this learning cannot be characterized as conscious.