Elsevier

Neuroscience

Volume 139, Issue 1, 28 April 2006, Pages 5-21
Neuroscience

What is working memory and how can we study it?
The multi-component model of working memory: Explorations in experimental cognitive psychology

https://doi.org/10.1016/j.neuroscience.2005.12.061Get rights and content

Abstract

There are a number of ways one can hope to describe and explain cognitive abilities, each of them contributing a unique and valuable perspective. Cognitive psychology tries to develop and test functional accounts of cognitive systems that explain the capacities and properties of cognitive abilities as revealed by empirical data gathered by a range of behavioral experimental paradigms. Much of the research in the cognitive psychology of working memory has been strongly influenced by the multi-component model of working memory [Baddeley AD, Hitch GJ (1974) Working memory. In: Recent advances in learning and motivation, Vol. 8 (Bower GA, ed), pp 47–90. New York: Academic Press; Baddeley AD (1986) Working memory. Oxford, UK: Clarendon Press; Baddeley A. Working memory: Thought and action. Oxford: Oxford University Press, in press]. By expanding the notion of a passive short-term memory to an active system that provides the basis for complex cognitive abilities, the model has opened up numerous questions and new lines of research. In this paper we present the current revision of the multi-component model that encompasses a central executive, two unimodal storage systems: a phonological loop and a visuospatial sketchpad, and a further component, a multimodal store capable of integrating information into unitary episodic representations, termed episodic buffer. We review recent empirical data within experimental cognitive psychology that has shaped the development of the multicomponent model and the understanding of the capacities and properties of working memory. Research based largely on dual-task experimental designs and on neuropsychological evidence has yielded valuable information about the fractionation of working memory into independent stores and processes, the nature of representations in individual stores, the mechanisms of their maintenance and manipulation, the way the components of working memory relate to each other, and the role they play in other cognitive abilities. With many questions still open and new issues emerging, we believe that the multicomponent model will continue to stimulate research while providing a comprehensive functional description of working memory.

Section snippets

The multi-component model of working memory

There are a number of ways in which the temporary storage of information can be realized within a cognitive system. One can for instance envision a distributed system with a set of independent processors that communicate with each other. Baddeley and Hitch (1974) instead argued for the concept of a common system that is “limited in capacity and operates across a range of tasks involving different processing codes and different input modalities” (Baddeley, 1986, p. 35). To support their claim,

The phonological loop

The phonological loop comprises two components, a phonological store, which holds memory traces in acoustic or phonological form that fade in a few seconds, and an articulatory rehearsal process analogous to subvocal speech (Baddeley, 1983). The function of the articulatory rehearsal process is to retrieve and re-articulate the contents held in this phonological store and in this way to refresh the memory trace. Further, while speech input enters the phonological store automatically,

The visuospatial sketchpad

While the phonological loop is specialized to hold verbal information, the visuospatial sketchpad is assumed to be capable of maintaining and manipulating visual and spatial information, a process that is crucial for performing a range of cognitive tasks. While initially, most working memory research focused on verbal material and therefore the phonological loop, recently a number of studies have provided a wealth of interesting results relating to the functional structure and properties of

The central executive

The central executive has been the most important but least understood and least empirically studied component of the multi-component working memory model (Baddeley 1986, Baddeley 1996). Initially, it was conceived in rather vague terms as a limited capacity pool of general processing resources. As such, it functioned as a homunculus and served as a convenient ragbag for unanswered questions related to the control of working memory and its two slave subsystems. While such a homunculus cannot

The episodic buffer

The episodic buffer is the latest addition to the multi-component model of working memory (Baddeley, 2000). It represents a separate storage system of limited capacity using a multi-modal code. It is episodic by virtue of holding information that is integrated from a range of systems including other working memory components and long-term memory into coherent complex structures: scenes or episodes. It is a buffer in that it serves as an intermediary between subsystems with different codes,

Cognitive neuroscience: the connection between brain and cognitive function

When describing a TV remote control, an electrician would be concerned with the exact circuitry employed that enables the emission of either the radio or infrared signal, a chemist would be interested in the compounds that enable the lightness and rigidity of the casing, while the user only wants to know which button to press for the desired effect. Every description of the remote control is valid and needed in its relevant context. Each contributes to the understanding of the remote control

General conclusions

We suggest that working memory has proved to be an important part of the cognitive system, providing the ability to maintain and manipulate information in the process of guiding and executing complex cognitive tasks. It can be fractionated into a number of independent subsystems, processes and mechanisms. It can usefully be described as a multicomponent system guided by an executive component consisting of a number of processes that provide attentional control over other components of working

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