Prda Report Baddely Article
JOURNAL OF VERBAL LEARNING AND VERBAL BEHAVIOR
14, 575-589 (1975)
Word Length and the Structure of Short-Term Memory
ALAN D. BADDELEY
Medical Research Council, Applied Psychology Unit
AND
NElL THOMSONAND MARY BUCHANAN
University of Stifling, Scotland
A number of experiments explored the hypothesis that immediate memory span is not constant, but varies with the length of the words to be recalled. Results showed: (1) Memory span is inverselyrelated to word length across a wide range of materials; (2) When number of syllables and number of phonemes are held constant, words of short temporal duration are better recalled than words of long duration; (3) Span could be predicted on the basis of the number of words which the subject can read in approximately 2 sec; (4) When articulation is suppressed by requiring the subject to articulate an irrelevant sound, the word length effect disappears with visual presentation, but remains when presentation is auditory. The results are interpreted in terms of a phonemically-based store of limited temporal capacity, which may function as an output buffer for speech production, and as a supplement to a more central working memory system.
Miller (1956) has suggested that the capacity of short-term memory is constant when measured in terms of number of chunks, a chunk being a subjectively meaningful unit. Because of the subjective definition of a chunk, this hypothesis is essentially irrefutable unless an independent measure of the nature of a chunk is available. Typically this problem has been avoided by making the simplifying assumption that such experimenter-defined units as words, digits, and letters constitute chunks to the subject.
Hence, although Miller 's hypothesis is not refutable in the absence of an independent measure of a chunk, it is meaningful to test a weaker version, namely that the capacity of short-term memory is a constant number of
We are grateful to the Social Science Research
Council and the Medical Research
14, 575-589 (1975)
Word Length and the Structure of Short-Term Memory
ALAN D. BADDELEY
Medical Research Council, Applied Psychology Unit
AND
NElL THOMSONAND MARY BUCHANAN
University of Stifling, Scotland
A number of experiments explored the hypothesis that immediate memory span is not constant, but varies with the length of the words to be recalled. Results showed: (1) Memory span is inverselyrelated to word length across a wide range of materials; (2) When number of syllables and number of phonemes are held constant, words of short temporal duration are better recalled than words of long duration; (3) Span could be predicted on the basis of the number of words which the subject can read in approximately 2 sec; (4) When articulation is suppressed by requiring the subject to articulate an irrelevant sound, the word length effect disappears with visual presentation, but remains when presentation is auditory. The results are interpreted in terms of a phonemically-based store of limited temporal capacity, which may function as an output buffer for speech production, and as a supplement to a more central working memory system.
Miller (1956) has suggested that the capacity of short-term memory is constant when measured in terms of number of chunks, a chunk being a subjectively meaningful unit. Because of the subjective definition of a chunk, this hypothesis is essentially irrefutable unless an independent measure of the nature of a chunk is available. Typically this problem has been avoided by making the simplifying assumption that such experimenter-defined units as words, digits, and letters constitute chunks to the subject.
Hence, although Miller 's hypothesis is not refutable in the absence of an independent measure of a chunk, it is meaningful to test a weaker version, namely that the capacity of short-term memory is a constant number of
We are grateful to the Social Science Research
Council and the Medical Research
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