No abstract

The role of attention in implicit sequence learning was investigated in 3 experiments in which participants were presented with a serial reaction time (SRT) task under single-or dual-task conditions. Unlike previous studies using this paradigm, these experiments included only probabilistic sequences of locations and arranged a counting task performed on the same stimulus on which the SRT task was being carried out. Another sequential contingency was also arranged between the dimension to be counted and the location of the next stimulus. Results indicate that the division of attention barely affected learning but that selective attention to the predictive dimensions was necessary to learn about the relation between these dimensions and the predicted one. These results are consistent with a theory of implicit sequence learning that considers this learning as the result of an automatic associative process running independently of attentional load, but that would associate only those events that are held simultaneously in working memory.

This article presents a review on the representational base of sequence learning in the serial reaction time task. The first part of the article addresses the major questions and challenges that underlie the debate on implicit and explicit learning. In the second part, the informational content that underlies sequence representations is reviewed. The latter issue has produced a rich and equivocal literature. A taxonomy illustrates that substantial support exists for associations between successive stimulus features, between successive response features, and between successive response-to-stimulus compounds. We suggest that sequence learning is not predetermined with respect to one particular type of information but, rather, develops according to an overall principle of activation contingent on task characteristics. Moreover, substantiating such an integrative approach is proposed by a synthesis with the dual-system model (Keele, Ivry, Mayr, Hazeltine, & Heuer, 2003).

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.

Individuals with autism spectrum condition (ASC) have diagnostic impairments in skills that are associated with an implicit acquisition; however, it is not clear whether ASC individuals show specific implicit learning deficits. We compared ASC and typically developing (TD) individuals matched for IQ on five learning tasks: four implicit learning tasks--contextual cueing, serial reaction time, artificial grammar learning, and probabilistic classification learning tasks--that used procedures expressly designed to minimize the use of explicit strategies, and one comparison explicit learning task, paired associates learning. We found implicit learning to be intact in ASC. Beyond no evidence of differences, there was evidence of statistical equivalence between the groups on all the implicit learning tasks. This was not a consequence of compensation by explicit learning ability or IQ. Furthermore, there was no evidence to relate implicit learning to ASC symptomatology. We conclude that implicit mechanisms are preserved in ASC and propose that it is disruption by other atypical processes that impact negatively on the development of skills associated with an implicit acquisition.