What brain structures and circuits are related to your selected deficit?

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Baddeley, A. D. (1978). The trouble with levels: A reexamination of Craik and Lockhart’s framework for memory research. Psychological Review, 85, 139-152.

Baddeley, A. D. (1992, January 31). Working memory. Science, 255, 556-559.

Baddeiey, A. D. (1996). Exploring the central executive. Quarterly Journal of Experimental Psychology, 49A, 5-28.

Baddeley, A. D. (2000). The episodic buffer: A new component of working memory? Trends in Cognitive Sciences, 4, 417-423.

Baddeley, A. D., & Andrade. J. (2000). Working memory and the vividness of imagery. Journal of Experimental Psychology: General, 129, 126-145.

Baddeley, A. D., Bressi, S., Delia Sala, S., Logie, R., & Spinnler, H. (1991). The decline of working memory in Alzheimer’s disease: A longitudinal study. Brain, 114, 2521-2542.

Baddeley, A. D., Emslie, H., Kolodny, J., & Duncan, J. (1998). Random generation and the executive control of working memory. Quarterly Journal of Experimental Psychology, 51A, 818-852.

Baddeley, A. D., Gathercole, S. E., & Papagno, C. (1998). The phonological loop as a language learning device. Psychological Review, 105, 158-173.

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Baddeley, A. D., Papagno, C , & Vallar, G. (1988). When long-term learning depends on short-term storage. Journal of Memory and Language, 27, 586-595.

Baddeley, A. D., Thomson, N., & Buchanan, M. (1975). Word length and the structure of short-term memory. Journal of Verbal Learning and Verbal Behavior, 14, 575-589.

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s Working Memory Still Working? Man I). Baddeley

University of Bristol

• The current state of A. D. Baddeley and G. J. Hitch’s (1974) multicomponent working memory model is reviewed. The phonological and visuospatial subsystems have been extensively investigated, leading both to challenges over interpretation of individual phenomena and to more detailed attempts to model the processes underlying the subsystems. Analysis of the controlling

Editor’s Note Alan D. Baddeley received the Award for Distinguished Scientific Contributions. Award winners are invited to de- liver an award address at APA ‘$ annual convention. This award address was delivered at the 109th annual meeting, held August 24-28, 2001, in San Francisco. Articles based on award addresses are not peer reviewed, as they are the expression of the winners’ reflections on the occasion of receiving an award.

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central executive has proved more challenging, leading to a proposed clarification in which the executive is assumed to be a limited capacity attentional system, aided by a newly postulated fourth system, the episodic buffer. Current interest focuses most strongly on the link between working memory and long-term memory and on the processes allowing the integration of information from the component subsystems. The model has proved valuable in accounting for data from a wide range of participant groups under a rich array of task conditions. Working memory does still appear to be working.

The term working memory appears to have been first pro- posed by Miller, Galanter, and Pribram (1960) in their classic book Plans and the Structure of Behavior. The term has subsequently been used in computational modeling ap- proaches (Newell & Simon, 1972) and in animal learning studies, in which the participant animals are required to hold information across a number of trials within the same day (Olton, 1979). Finally, within cognitive psychology, the term has been adopted to cover the system or systems involved in the temporary maintenance and manipulation of information. Atkinson and Shiffrin (1968) applied the term to a unitary short-term store, in contrast to the pro- posal of Baddeley and Hitch (1974), who used it to refer to a system comprising multiple components. They empha- sized the functional importance of this system, as opposed to its simple storage capacity. It is this latter concept of a multicomponent working memory that forms the focus of the discussion that follows. I myself have been using the concept for over 25 years; does it still work?

Before addressing this issue, it is perhaps appropriate to consider what are the criteria for working. The multicom- ponent model of working memory was proposed as a theo- retical framework whose function was to give an economi- cal and coherent account of a relatively wide range of data. Its success should be judged in terms of its continuing ca- pacity to do so and to prompt new questions that in turn add to the basic understanding of cognition. To work, therefore, requires breadth of coverage coupled with a ca- pacity to stimulate further research and to incorporate more precise quantitative and/or computational models. So, how well is working memory working?

Baddeley and Hitch (1974) proposed that the earlier uni- tary concept should be elaborated into a three-component system. As Figure 1 shows, this comprises a limited capac-

Figure 1 The Model of Working Memory Proposed by Baddeley and Hitch (1974)

ity attentional controller, the central executive, aided by two subsystems, one concerned with acoustic and verbal information, the articulatory (subsequently phonological) loop, and the other performing a similar function for visual and spatial information, the visuospatial scratchpad (subse- quently sketchpad).1 Much of the earlier work concentrated on these two subsystems, on the grounds that they ap- peared to offer more tractable problems than did the central executive. For that reason, they are discussed first.

The Phonological Loop

This system was proposed to give an account of the sub- stantial evidence that had already accumulated concerning short-term verbal memory, typically involving the classic digit span procedure. The articulatory loop was assumed to comprise two components, a phonological store and an ar- ticulatory rehearsal system. Traces within the store were assumed to decay over a period of about two seconds un- less refreshed by rehearsal, a process akin to subvocaliza- tion and one that is dependent on the second component, the articulatory system (Baddeley & Hitch, 1974).

The store was assumed to be reflected in the phonologi- cal similarity effect, whereby immediate serial recall of items that are similar in sound (e.g., the letters B, V, G, T, C, D) is poorer than that of dissimilar items (e.g., F, K, Y, W, M, R; Conrad & Hull, 1964). Similarity of meaning, however, typically has little effect in the standard immedi- ate serial recall paradigm (Baddeley, 1966b). The reverse is true of the multitrial long-term learning of 10-item se- quences, which appears to depend principally on semantic rather than acoustic coding (Baddeley, 1966a).

The articulatory rehearsal component was proposed to give an account of the word length effect, whereby imme- diate serial recall is a direct function of the length of the items being retained (Baddeley, Thomson, & Buchanan, 1975). Hence, a sequence such as sum, pay, wit, bar, hop is much more likely to be recalled correctly than helicop- ter, university, television, alligator, opportunity. This was originally proposed to reflect the slower rehearsal of longer words, which allows greater forgetting. It has also been claimed to result from forgetting during the process of re- call, which again tends to be slower with longer words (Cowan et al., 1992; Dosher & Ma, 1998). It now appears that both of these processes are important (Baddeley, Chin- cotta, Stafford, & Turk, in press). Consistent with this view is the fact that when rehearsal is prevented by articulatory suppression, the repetition of an irrelevant sound such as the word the, the word length effect disappears (Baddeley et al., 1975).

Visuospatial Sketchpad

Central k Executive^,

Phonological Loop

‘ Articulatory was changed to phonological to emphasize the fact that this subsystem is not limited to the articulatory component. The term sketchpad was adopted to emphasize that subsystem’s visuospatial char- acteristics.

852 November 2001 • American Psychologist

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