ABSTRACT
The model developed by Waugh and Norman, which is represented in Figure 4.1, consists of two stores, primary memory (PM) and secondary memory (SM). Stimulus information is entered into the small capacity PM from where it may be copied into SM which is assumed to have virtually unlimited storage capacity. The model was devel oped in the context of experiments involving verbal items, that is digits, letters and words. Hence, while Waugh and Norman made no strong assumptions about the nature of coding in PM they did suggest that stimulus information has been fully categorized into verbal units before entering it. Subsequent work has supported this view by showing that
the capacity of PM remains at about 3 words irrespective of the number of syllables they contain (e.g. Craik, 1968a). If PM were precategorical then it would be reasonable to expect that some unit of coding rather more primitive than whole words, such as syllables, would form the basis of coding and hence of capacity.
