Can we build endogenous expectations about the locus of occurrence of a target without being able to describe them? Participants performed cue–target detection tasks with different proportions of valid and invalid trials, without being informed of these proportions, and demonstrated typical endogenous effects. About half were subsequently able to correctly describe the cue–target relationships . However, even non-verbalizer participants showed endogenous orienting with peripheral cues , not depending solely on practice . Explicit instructions did not bring about dramatic advantages in (...) performance .With central symbolic cues, only verbalizers showed reliable endogenous effects . We concluded that endogenous orienting with peripheral cues can occur independently of participants developing explicit hypotheses about the cue–target relationships. (shrink)

It is well known that the difference in performance between valid and invalid trials in the covert orienting paradigm increases as the proportion of valid trials increases. This proportion valid effect is widely assumed to reflect “strategic” control over the distribution of attention. In the present experiments we determine if this effect results from an explicit strategy or implicit learning by probing participant’s awareness of the proportion of valid trials. Results support the idea that the proportion valid effect in the (...) covert orienting paradigm reflects implicit learning not an explicit strategy. (shrink)

A number of ways of taxonomizing human learning have been proposed. We examine the evidence for one such proposal, namely, that there exist independent explicit and implicit learning systems. This combines two further distinctions, (1) between learning that takes place with versus without concurrent awareness, and (2) between learning that involves the encoding of instances (or fragments) versus the induction of abstract rules or hypotheses. Implicit learning is assumed to involve unconscious rule learning. We examine the evidence for implicit learning (...) derived from subliminal learning, conditioning, artificial grammar learning, instrumental learning, and reaction times in sequence learning. We conclude that unconscious learning has not been satisfactorily established in any of these areas. The assumption that learning in some of these tasks (e.g., artificial grammar learning) is predominantly based on rule abstraction is questionable. When subjects cannot report the rules that govern stimulus selection, this is often because their knowledge consists of instances or fragments of the training stimuli rather than rules. In contrast to the distinction between conscious and unconscious learning, the distinction between instance and rule learning is a sound and meaningful way of taxonomizing human learning. We discuss various computational models of these two forms of learning. (shrink)

A number of ways of taxonomizing human learning have been proposed. We examine the evidence for one such proposal, namely, that there exist independent explicit and implicit learning systems. This combines two further distinctions, between learning that takes place with versus without concurrent awareness, and between learning that involves the encoding of instances versus the induction of abstract rules or hypotheses. Implicit learning is assumed to involve unconscious rule learning. We examine the evidence for implicit learning derived from subliminal learning, (...) conditioning, artificial grammar learning, instrumental learning, and reaction times in sequence learning. We conclude that unconscious learning has not been satisfactorily established in any of these areas. The assumption that learning in some of these tasks is predominantly based on rule abstraction is questionable. When subjects cannot report the “implicitly learned” rules that govern stimulus selection, this is often because their knowledge consists of instances or fragments of the training stimuli rather than rules. In contrast to the distinction between conscious and unconscious learning, the distinction between instance and rule learning is a sound and meaningful way of taxonomizing human learning. We discuss various computational models of these two forms of learning. (shrink)

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Chica and Bartolemeo : The proportion valid effect in covert orienting: Strategic control or implicit learning? Consciousness and Cognition,19, 443–444.) agree that our results . The proportion valid effect in covert orienting: Strategic control or implicit learning? Consciousness and Cognition,19, 432–442.) are consistent with an implicit learning account of the proportion valid effect. Nevertheless, they raise two general issues that an explicit strategy might be operative in other contexts and that orienting in response to implicit knowledge is endogenous. In our (...) response, we address each of these issues and further discuss the concepts of endogenous orienting and cognitive control. (shrink)