IMPLICIT LEARNING - BELOW THE SUBJECTIVE THRESHOLD

In this review, we consider three possible criteria by which knowledge might be regarded as implicit or inaccessible: It might be implicit o nly in the sense that it is difficult to articulate freely, or it migh t be implicit according to either an objective threshold or a subjecti ve threshold. We evaluate evidence for these criteria in relation to a rtificial grammar learning, the control of complex systems, and sequen ce learning, respectively. We argue that the convincing evidence is no t yet in, but construing the implicit nature of implicit learning in t erms of a subjective threshold is most likely to prove fruitful for fu ture research. Furthermore, the subjective threshold criterion may dem arcate qualitatively different types of knowledge. We argue that (1) i mplicit, rather than explicit, knowledge is often relatively inflexibl e in transfer to different domains, (2) implicit, rather than explicit , learning occurs when attention is focused on specific items and not underlying rules, and (3) implicit learning and the resulting knowledg e are often relatively robust.