No abstract

Four experiments investigate the differences between implicit and explicit sequence learning concerning their resilience to structural and superficial task changes. A superficial change that embedded the SRT task in the context of a selection task, while maintaining the sequence, did selectively hinder the expression of implicit learning. In contrast, a manipulation that maintained the task surface, but decreased the sequence validity, affected the expression of learning specifically when it was explicit. These results are discussed in the context of a dynamic framework (Cleeremans & Jiménez, 2002), which assumes that implicit knowledge is specially affected by contextual factors and that, as knowledge becomes explicit, it allows for the development of relevant metaknowledge that modulates the expression of explicit knowledge.

Dyslexia is a specific learning disability characterized by difficulties with accurate and/or fluent word recognition and by poor spelling abilities. The absence of other high level cognitive deficits in the dyslexic population has led some authors to propose that non-strategical processes like implicit learning could be impaired in this population. Most studies have addressed this issue by using sequence learning tasks, but so far the results have not been conclusive. We test this hypothesis by comparing the performance of dyslexic children and good readers in both implicit and explicit versions of the sequence learning task, as well as in another implicit learning task not involving sequential information. The results showed that dyslexic children failed to learn the sequence when they were not informed about its presence (implicit condition). In contrast, they learned without significant differences in relation to the good readers group when they were encouraged to discover the sequence and to use it in order to improve their performance (explicit condition). Moreover, we observed that this implicit learning deficit was not extended to other forms of non-sequential, implicit learning such as contextual cueing. In this case, both groups showed similar implicit learning about the information provided by the visual context. These results help to clarify previous contradictory data, and they are discussed in relation to how the implicit sequence learning deficit could contribute to the understanding of dyslexia.

We report two experiments in which implicit learning is demonstrated within a short session of practice, in the absence of explicit knowledge of what is learned. In Experiment 1, we replicate the experiments by Curran (Psychol Res 60:24-41, 1997a; J Cogn Neurosci 9(4):522-533, 1997b) and highlight the importance of avoiding a random sequence as comparison to the training sequence, due to the higher proportion of reversal trials included in the random one, which leads to an artifactual measure of learning. In Experiment 2 we present a procedure in which two structurally analogous sequences are used both as training and control sequences, thus controlling for any factor different from learning. The results show that implicit learning is obtained within a short session of practice, and in the absence of any explicit knowledge as assessed through a subsequent generation task. We surmise that this procedure might be especially useful in areas in which short procedures are needed, such as when special populations are tested (e.g., patients, children or elderly people) or when the neural bases of implicit learning are being investigated through neurophysiological measures.