Lecturer's Précis - Allport (1985)
"Distributed Memory, Modular Systems and Dysphasia"
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First published online11:01 GMT 11th March 2002, Copyright Derek J. Smith (Chartered Engineer). This version [HT.1 - transfer of copyright] dated 18:00 14th January 2010
An earlier version of this material appeared in Smith (1996; Chapter 6). It is repeated here with minor omissions but supported with hyperlinks.
1 - The Concept of "Attribute Domains"
Allport (1985) considered how matrix memory (ie. cell assembly engrams) might be distributed physically using all the available cerebral cortex. Would a given engram be diffused across the entire cortical surface, he asked, or would it be to some extent localised? He concluded that a matrix memory storage system can be both localised and distributed at the same time. The way Allport saw this working was for the cell assemblies (for object concepts, at least) to be distributed across a range of what he called "attribute domains" (p52). These are areas of cortex specialised to store engrams in a particular sensory or motor modality (as shown schematically in the Figure below). Thus for the different sensory modalities there would be a visual domain, an auditory domain, a tactile domain, and so on. These would be supported by two essentially motor engram domains, namely (a) a kinaesthetic domain, which would store engrams relating to the body movements involved in physically manipulating the object in question, and (b) an action orientated domain which would store higher-order motor data such as what sequence individual behavioural steps are to be executed in. In other words, attribute domains help organise memory by clustering like with like: each domain simply looks after its share - or "element" - of the total engram.
Allport's (1985) "Attribute Domains": The various sensory-motor attribute domains are shown at the top of the figure (orange). Colour attributes are seen as being part of the visual domain, and smell and taste are not shown at all. The sensory-motor domains are supported by two major lexical stores (green), a phonological lexicon containing the sound forms of words, and an orthographic lexicon containing the written forms of words. Note the distribution of the engram for <telephone> across all domains, and the close association between the engrams for <clouds> and <thunder>. If rotated to the right, and if the lexicons are subdivided into separate input and output stores, the diagram may be seen as a modern development of Freud's (1891) diagram.
Redrawn from a black and white original in Allport (1985:53). This version Copyright © 2002, Derek J. Smith.
Exercise - Attribute Domains
1 Print the above figure (preferably enlarging it to at least A4 size) and highlight the following concepts:
footbrake; telephone; velvet; cloud.
2 Add in the following concepts:
orange (fruit); orange (colour); bell; screwdriver; ice-cube; rainbow; honesty; fear; with; and; because; walk (verb); walk (noun); him; very
3 Consider how the word-concept links would cope with homophones such as:
mine (possessive pronoun); mine (noun (1) = bomb); mine (noun (2) = hole in the ground); mine (verb (1) = to plant a bomb); mine (verb (2) = to extract from a hole in the ground)
4 Consider how the word-concept links would work in bilinguals. Try the following English, German, and French versions of footbrake:
footbrake; Bremse; frein
2 - Auto-Association
We deal with Allport's views on cell assembly theory in Section 3 of our e-handout on "Hebbian Theory".
3 - References