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Verbal Working Memory

Verbal working memory has long been understood through the "Phonological Loop" model, one part of the Working Memory theory proposed by Alan Baddeley. Although it is a parsimonious explanation that captures many of the major trends of the empirical data, it is not specified sufficiently well enough to evaluate whether the claims associated with the theory actually predict the magnitude of various effects.

Using the EPIC architecture, we have developed explicit models of the phonological loop, and achieved several insights. First, we found that in order to correctly recall lists of words, phonological traces of those words must remain for between 4 and 10 seconds, much longer than 2 seconds that is frequently claimed. Second, we have determined that internally generated memory traces have different mnemonic properties than traces generated externally (through perceptual processes). Third, we have revealed that the executive processes involved in maintaining a phonological loop are quite substantial, and that the "simple memory span" task is actually complex.

Using these insights to guide further empirical and theoretical work, we have also developed measures of two of the most critical predictors of verbal memory ability; phonological similarity and word length. These advances allow data to be more precisely analyzed in the context of the phonological loop model.

We have also have begun to explore the properties of the VWM by formulating neural-network models of the storage and maintenance of symbolic verbal information.

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