Handbook of implicit learning. Thousand Oaks, CA: Sage. Publications, Inc. 636 pp. ISBN #0-7619-0197-3. All twenty-nine writers of this important volume share ...
Dulany,D.E. (2000) Learning explicitly about learning implicitly. PsycCRITIQUES, 45(01), 19-24. Preprint Version Explicit Learning About Implicit Learning Stadler, M.A, and Frensch, P.A. (1997). Handbook of implicit learning. Thousand Oaks, CA: Sage Publications, Inc. 636 pp. ISBN #0-7619-0197-3. All twenty-nine writers of this important volume share an intuition, as do I, that not all learning is active and reflective, that it is sometimes more passive and automatic--in some sense. Using a task George Miller (1958) introduced, the task of learning what obeys a finite state grammar, Arthur Reber (1967) described and experimentally examined something he christened "implicit learning," distinguishing it from the "explicit learning" that had been the central concern of the field of learning for decades. Thirty years and scores of studies later, Michael Stadler and Peter Frensch have provided a highly valuable service by convening these experts in the production of handbook that explores that intuition systematically, asking just what implicit learning really is, how it should be investigated, and where we might stand on the central theoretical issues. Indeed, this volume is divided into sections announcing each of those topics, but I am not surprised to see that all 18 chapters tap all three of these inevitably interrelated concerns. What it is. Under the heading of "Defining implicit learning," Frensch's early chapter runs us through eleven conceptions, mine (Dulany, 1997) included, none of which is or should properly be considered to be a definition. Any phenomenon complex enough to draw thirty years of controversy lacks the simplicity a definition could capture. We should begin by elaborating and refining the core intuition, letting implicit learning come to be specified by a theory or theories of implicit learning that are submitted to experimental examination. In fact, that characterizes the work reviewed and presented in these 18 chapters. Given all the animated controversy, it would be tempting to say that it is only the original intuition that is conspicuously common. Seger's chapter describes variants as "multiple forms of implicit learning," and chapters by Frensch, Curran, and Willingham, discuss possible loci of implicit learning in perceptual, central, and motor systems, in some cases drawing on brain imaging studies to implicate neural mechanisms. Nevertheless, the chapters throughout show clearly that a "standard theory" can be broadly outlined, and competing conceptions depart on central issues for the discipline: the roles of highly specific reactions and higher-order abstraction processes, and--most significantly--the roles of consciousness and nonconscious processes, the subject of Stadler and Roediger's early chapter. How it has been studied. Consider viewing strings of letters generated by a finite state grammar, then judging whether other strings are grammatical or not--the inaugurating "FSG task"
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from Miller and Reber. Or think of trying to respond quickly to a figure that shows up systematically but often surprisingly in one of four positions--"sequence learning" or "SRT." Or imagine repeatedly trying to please, making overtures of varying warmth to a "person in a computer" who responds on some obscure algorithm--in essence, a "dynamic system." You might even be asked to say whether pictured persons with long or short hair are "kind" or not after hair length has been subtly associated with the kindness of strangers. Call it "hidden covariation." These odd little tasks, and others quite similar, do have a purpose: They embody structures to be somehow grasped, as does the world at large, and so we naturally ask whether they are learned by abstracting those structures, as Reber and others in these chapters hold, or by selecting out more specific information that serves well enough, as Perruchet, Shanks, and others hold. Furthermore, whatever is learned must somehow represent aspects of the task when used, and the structure of each task is kept relatively non-salient, raising the second of the central questions in the literature: Is the symbolic representation unconscious, as Reber and many hold, or only represented in consciousness, as challenges from Perruchet, Shanks, this writer and their co-workers have held? Those process issues in turn raise methodological issues. When subjects learn in the sequence task, for example, can abstraction of the sequence rule be inferred from an increase in RT when the sequence rule is changed, as Lewicki and co-workers reported? Or are changes in RT generated by more specific differential response frequencies, as the work of Perruchet and coworkers has indicated? This and related methodological issues are examined at length in chapters by Buchner & Wippich, Berry & Cock, Reed & Johnson, Perruchet & Vintner, and Shanks & Johnstone. Furthermore, Mathews and Cochran ask what generativity might imply about an underlying structure--an interesting question that echoes well-known views within psycholinguistics. What, too, are the conditions under which a secondary task might provide a useful manipulation of awareness or attention, or the conditions under which subjective reports or objective recognition and generation responses might provide valid indices of awareness? These and closely related issues are examined in many chapters, perhaps most fully in chapters by Stadler & Roediger, Cleermans & Jimenez, Goshke, and Shanks & Johnstone. Theoretical issues. Although neither this review nor these chapters could observe neat divisions among concept, method, and issues, I believe the issues can be illuminated by placing them in context of a "standard theory" of implicit learning. It runs through many of these chapters and shows the strong influence of Reber's original formulation: Implicit learning is said to (a) occur incidentally, with no intention to learn or with intention to learn directed elsewhere, commonly in a memorization task. (b) The learning is accomplished by a "nonconscious abstraction system" that can count instances and extract rules that describe regularities. (c) The knowledge acquired is "tacit knowledge," an unconscious symbolic representation of a domain that can control action while unaccessed to consciousness and perhaps inaccessible. (d) Furthermore, implicit learning is aroused when the regularities to be learned are complex and non-salient and beyond the grasp of any ordinary consciousness. In short, implicit learning, it is often said, is unconscious learning--and when the going gets tough, the unconscious gets going.
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This kind of learning is usually contrasted with explicit learning, variously described, but usually said to consist of intentional learning by conscious hypothesis testing that leads to consciously accessible rules guiding action. Explicit learning, conventionally, is conscious learning. In fact, the distinction as made in most of these chapters, sits well with the standard cognitive metatheory. As Berry and Broadbent (1988) put it, "A central distinction in cognitive psychology is that made between explicit or conscious thinking and implicit or unconscious thinking" (p. 251). And why not? On standard information processing architectures, cognitive activity can occur within a working memory either inside or outside a small region of conscious attention. And on a common computational view, cognition occurs apart from consciousness, implicitly, and is only sometimes displayed there epiphenomenally, explicitly. So let us be clear about it. When this theory of implicit learning is challenged, by Perruchet and Vintner's chapter, Shanks and Johnstone's chapter, (or my own writing, for that matter), it constitutes one kind of challenge to an entrenched metatheory. That metatheory prescribes fully formed mental episodes outside consciousness, episodes that could encompass an abstraction process and the decision to use a tacit abstraction. `A modest wish list. Reading these chapters I wished for fuller and clearer expression of alternative theory. The basic intuition of a more passive and automatic kind of learning can be realized even in theory of nonconscious mental operations exclusively establishing activational associations among conscious contents, and in some tasks, inter-linking those contents with actions. There is some of this in the Perruchet & Vintner chapter and in Shanks & Johnstone's chapter. Theoretical development also has implications for methodology. On an alternative theory, for example, sequential learning could proceed by the establishment of activational relations among conscious contents, contents presented to the learner's consciousness on every trial. Even if sequential rules were not always verbalizable, as Shanks & Johnstone acknowledge, failure to meet conditions for metacognitive awareness of rules and their verbalization would not imply that learning had not consisted of establishment of associations among first-order contents of consciousness. What is presented to awareness may substitute for what is reported from awareness. ` With that kind of theoretical development, too, perhaps it would be more widely recognized that the "objective indices" of awareness need not be thought to be, as the worry goes, "contaminated by unconscious processes." And on the same kind of theory, an implicit memory test of implicit learning would not be viewed as tapping "unconscious memory" of what is not consciously remembered at the moment, an essential of the standard theory of implicit learning. There is considerable and strong evidence of the specificity of those effects to what occurs--in awareness--at learning and test (e.g. Roediger & Srinivas, 1993). When a learned item becomes more recognizable, or identifiable, or "completable" at test, we would see strengthening of a nonconscious (but non-contaminating) activational relation between its literal awareness and identity awareness or an activational relation among conscious contents in sequence.
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Most fundamentally, I think, both implicit and explicit learning would be recognized as involving both conscious contents and intrinsically nonconscious mental operations. In explicit learning, nonconscious deliberative operations of inference, decision, and judgment would transform propositional conscious contents. And in implicit learning, nonconscious evocative operations, those establishing and using associative activation, would transform non-propositional contents--a "sense of..." or "identity of..." Implicit learning differs significantly from explicit learning in the forms of the mental operations and contents, but I think one is no more conscious or non-conscious than the other. Contribution. Aside from any of that, however, this volume makes an important contribution in presenting authoritative reviews of important evidence, along with thoughtful discussions of methodological issues and theoretical issues now motivating the inquiry. There have been other valuable but much briefer collections. This volume performs the very valuable service of bringing a large literature together in a way that tells us where we are and suggests where we should go--at least in some of the directions. The editors and authors are to be commended for that contribution. References Berry, D.C., & Broadbent, D.E. (1988) Interactive tasks and the implicit-explicit distinction. British Journal of Psychology, 79, 251-272. Dulany, D.E. (1997). Consciousness in the explicit (deliberative) and implicit (evocative). In Cohen, J.D., & Schooler, J.W. (Eds.) Scientific approaches to consciousness (pp. 179-211). Mahwah, NJ: Lawrence Erlbaum Associates, Inc. Miller, G.A. (1958). Free recall of redundant strings of letters. Journal of Experimental Psychology, 56, 485-491. Reber, A.S. (1967). Implicit learning of artificial grammars. Journal of Verbal Learning and Verbal Behavior, 6, 855-863. Roediger, H.L., & Srinivas, K. (1993). Specificity of operations in perceptual priming. In P. Graf & J.E.J. Masson (Eds.) Implicit memory: New directions in cognition, development, and neuropsychology (pp. 17-48). Hillsdale, NJ: Lawrence Erlbaum Associates.
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