ABSTRACT
Comparing the relative sensitivity of direct and indirect measures of learning is proposed as the best way to provide evidence for unconscious learning when both conceptual and operative definitions of awareness are lacking. This approach was first proposed by Reingold & Merikle (1988) in the context of subliminal perception. In this paper, we apply it to a choice reaction task in which the material is generated based on a probabilistic finite-state grammar (Cleeremans, 1993). We show (1) that subjects progressively learn about the statistical structure of the stimulus material over training with the choice reaction task, and (2) that they can use some of this knowledge to predict the location of the next stimulus in a subsequent explicit prediction task. However, detailed partial correlational analyses of the correspondence between CRT performance and the conditional probability of each stimulus showed that large effects remained even when controlling for explicit knowledge as assessed by the prediction task. Hence we conclude (1) that at least some of the knowledge expressed in CRT performance can not be characterized as conscious, and (2) that even when associations are found at a global level of analysis, dissociations can still be obtained when more detailed analyses are conducted. Finally, we also show that subjects are limited in the depth of the contingencies they can learn about, and that these limitations are shared by the Simple Recurrent Network model of Cleeremans & McClelland (1991).
