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Random generation and the executive control of working memory.
BADDELEY, A., EMSLIE, H., KOLODNY, J. & DUNCAN, J.
Quarterly Journal of Experimental Psychology, 1998, 51A (4), 819-852.
Year of publication:
A series of experiments explores the capacity for generating sequences of random responses, relating it to the central executive component of working memory. Experiment 1 shows a broadly similar pattern of redundancy increasing with speed of generation for both the verbal generation of digits and the manual pressing of keys. In both cases deviations from randomness are shown to reflect the increasing use of a limited number of stereotyped response sets. The remaining experiments use keyboard generation, with Experiment 2 demonstrating that concurrent immediate serial recall decreases randomness, with longer sequences producing less random output. Experiments 3 and 4 show that whereas simple counting had no effect on randomness, serial recall, semantic category generation and concurrent digit generation had substantial effects, while a concurrent fluid intelligence test had the greatest influence on the randomness of key pressing. It is suggested that the task of random generation resembles that of category fluency in requiring the subject to switch retrieval plans and inhibit repetition. On this basis it was predicted that a task involving repeated switching of categories would interfere with generation, despite being predictable and having a low memory load. Experiments 5 and 6 confirm this prediction.