Working Memory: The Interfhce between Memory and Cognition Alan Baddeley MRC Applied Psychology Unit Cambridge, England Downloaded from http://mitprc.silverchair.com/jocn/article-pdf/4/3/281/1754997/jocn.1992.4.3.281.pdf by guest on 18 May 2021 Abstract Working memory may be defined as the system for the system is proposed within a broad and relatively speculative 1 Downloaded from http://direct.mit.edu/jocn/article-pdf/4/3/281/1932205/jocn.1992.4.3.281.pdf by guest on 28 September 2021 temporary maintenance and manipulation of information, nec- overview of human memory that emphasizes the putative role essary for the performance of such complex cognitive activities of working memory. This is followed by a brief account of a as comprehension, learning, and reasoning. Used in this sense, particular model of working memory, and a more detailed the term refers to an area of research that may or may not discussion of the way in which the various subcomponents of prove to be dependent on a single coherent system. Such a the model relate to other aspects of memory and cognition. HUMAN MEMORY A SPECULATIVE ness provides a convenient way of simultaneously OVERVIEW representing such diverse streams of information about a common object, although it is almost certainly not the I assume that memory, along with other cognitive capac- only way (see Baddeley, 1992a,b for a discussion). ities, has evolved to allow the organism to cope with a complex but structured world. The world is never en- Aspects of Learning tirely predictable, but has sufficient regularity to make it advantageous for the organism to use the past in order Whereas a working memory system that coordinates in- to predict the future, that is, to make use of learning and formation from a number of sources is likely to aid memory. perceptual organization of the world, it woiild not nec- essarily benefit from experience. Hence, it would not form concepts such as would be necessary to recognize Working Memory and Perception a cat as such, nor would it allow one to learn that cats Before learning can take place, an organism must be able tend to hiss rather than bark. More importantly perhaps, to perceive the world, and preferably take advantage of it would not allow one to know whether cats were dan- the fact that the information from the range of sensory gerous, or indeed to recognize one’s own cat, or of channels is likely to be correlated. Objects have not only course to remember whether it had already been fed or visual and spatial characteristics, but are likely also to not. It is now widely accepted that long-term memory is have associated tactile features, and quite possibly to have not a simple unitary system, although there is consider- a characteristic smell and taste. It seems likely that per- ably less agreement as to how it should be conceptual- ceiving and integrating these various sources of infor- ized (Richardson-Klavehn & Bjork, 1988). mation would benefit from at least a temporary form of There are two major dimensions along which it has in storage, both to allow for extended processing, and also the past been proposed to dichotomize long-term mem- for the fact that the evidence from the various channels ory: one is the proposed distinction between semantic may not always be available simultaneously. Indeed in and episodic memory, and the other uses a rather some cases, such as the subsequent taste of an orange, broader range of terminology of which the implicit and or the sound emitted by cat, information on one channel explicit memory distinction is one of the most widely such as vision, may arrive substantially before that of adopted. Semantic memory is the term applied by Tul- others. It could be argued that this capacity to integrate ving to the storage of information about the world, the sensory information requires some form of working name of the capital of France, or the chemical formula memory, particularly if the system is one that actively for salt, for example. Episodic memory, on the other attempts to build up information about a perceived ob- hand, refers to the recollection of a personally experi- ject. Furthermore, it can be argued that conscious aware- enced event. In its earlier formulations, the theoretical 0 1992 Masachusetts Institute of Technology Journal of Cognitive Neuroscience Volume 4, Number 3 emphasis tended to be on the basic separability of the learning of the varied probabilities of events can readily underlying systems (Tulving, 1972). Later developments be simulated using connectionist networks, employing have tended rather to emphasize the more phenome- one of a range of possible learning algorithms (Rumel- nological aspects of episodic memory, which is assumed hart, 1991). to be associated with the conscious recollection of the earlier episode (Tulving, 1983). Episodic Memory The implicit-explicit memory distinction, which is also sometimes described as a procedural4eclarative or The limitation of such basic accumulative learning pro- direct-indirect memory distinction, has developed more cesses, however, is that they do not allow the organism recently to reflect the observation that certain types or to select one specific episode from the agglomeration of aspects of memory (implicit) appear to differ markedly prior experience. For this a different form of associative from the pattern of function typically observed in labo- learning is required (Rumelhart, 1991), which I would ratory learning and memory studies (explicit). Such tra- like to suggest corresponds to episodic memory. If the Downloaded from http://mitprc.silverchair.com/jocn/article-pdf/4/3/281/1754997/jocn.1992.4.3.281.pdf by guest on 18 May 2021 ditional studies are typically concerned with the subject’s organism is to retrieve a specific episode, then it must explicit capacity to recall or recognize material; they have a means of specifying that episode. The most likely show that performance is a function of variables such as mechanism would seem to be via the use of context. It the depth of processing of the material, its meaningful- is assumed that the episodic learning mechanism is ca- ness, and its degree of active organization. pable of very rapidly forming links between stimuli that Downloaded from http://direct.mit.edu/jocn/article-pdf/4/3/281/1932205/jocn.1992.4.3.281.pdf by guest on 28 September 2021 In contrast, implicit or indirect memory measures are are experienced at the same time. Such a link will allow able to reveal other aspects of learning, which appear to one such experience to evoke the other, hence if I met be insensitive to depth of processing, and much less Charlie and Gladys together at the Green Dragon pub, influenced by strategies and organizational variables. then meeting Charlie is likely to remind me of both This latter type of learning also tends to be relatively Gladys and the pub. intact in a wide range of neuropsychological patient Clearly the extent of such retrieval needs to be limited, groups who typically have impairment in explicit declar- otherwise the regulars at the Green Dragon, on entering ative or directly tested memory. Although there is con- the pub, would be overcome by a bombardment of mem- siderable agreement as to the existence and importance ories of everyone they had ever met there, potentially of such distinctions, there is considerably less agreement causing serious interference with the main purpose of as to the best way of theoretically interpreting this rich their visit. The study of the utilization and operation of and rapidly growing research area. Broadly speaking, such retrieval cues has, of course, formed one of the proponents fall into two categories; the first attempt to most active and successful areas of recent memory re- explain the data as reflecting different aspects of a unitary search (Tulving, 1983). memory system (e.g., Jacoby, Baker, & Brooks, 1989; I assume that this process of retrieval from episodic Roediger, 1990), and typically concentrate on data from memory makes a representation of an earlier episode normal subjects. On the other hand, those who argue accessible to working memory, allowing the central ex- for two, or possibly more separate memory systems (e.g., ecutive component of workmg memory to reflect on its Squire & Zola Morgan, 1988; Tulving & Schacter, 1990) implications and choose an appropriate action. Suppose are typically concerned to account for both normal and that I had chatted to Gladys and been told that Charlie neuropsychological evidence. As will become clear, my always went to that particular pub on Tuesday evenings, own views tend to be of this kind, then recollection of that experience would be rather Given that the world is to some extent a predictable useful if I wanted to make sure that I met him. In contrast, place, then it makes sense for the organism to be able a learning mechanism that simply strengthened the as- to capitalize on such predictability, to learn, for example, sociation between Charlie and the pub would be much that food of one kind is typically found in one location, less helpful. water in another, while a third may be associated with danger. The organism will also find it advantageous to Predicting the Future be able to acquire novel skills, allowing hunting to be carried out more effectively, or in the case of humans So far we have discussed the role of memory as providing for language to develop. At a rather more basic level, information about the past; however, the principal value there may be advantages to priming, whereby the oper- of such information is for the light it throws on the future, ation of a particular cognitive process may facilitate the and here again working memory becomes crucial in two subsequent operation of that process (positive priming), ways.