Implicit (and explicit) learning: acting adaptively without knowing the consequences.

Subjects exposed to members of a structured domain become sensitive to the general structure of that domain, even when unaware that the domain has such structure. Numerous investigators have taken this as evidence for a mode of learning in which memory passively and unselectively absorbs the structure of the environment. The authors contend that this assumption miscasts the fundamental nature of learning. The authors demonstrate that even when task and stimulus structure are held constant, subjects react to variations in incidental stimulus properties by processing the stimuli in qualitatively different ways. The authors conclude that implicit learning, just like explicit learning, proceeds through active organization of the stimulus complex, rather than through passive absorption of any level of structure. The authors propose a synthesis in which learning, with and without awareness, is understood through a common set of principles.