DISCUSSION

All three experiments agree in showing a large and consistent adverse effect of acoustic similarity on ordered STM for words, and Experiments I and II show that neither semantic nor formal similarity has an effect of comparable magnitude. The relative unimportance of semantic similarity shown in Experiment I together with the failure of Baddeley and Dale (1966) to find an effect of semantic similarity among stimuli on STM for paired associates suggests that subjects show remarkable consistency and uniformity in using an almost exclusively acoustic coding system for the short-term remembering of disconnected words. There is abundant evidence that this is not true of LTM (Underwood, 1951; Underwood and Goad, 1951; Baddeley, 1966; Baddeley and Dale, 1966).

REFERENCES

BADDELEY, A. D. (1966). The influence of acoustic and semantic similarity on long-term memory for word sequences. Quart. J. exp. Psychol., 18, 302-9.

BADDELEY, A. D., and DALE, H. C. A. (1966). The effect of semantic similarity on retro-active interference in long- and short-term memory. J. verb. Learn, erb. Behav. (in press).

CONRAD. R. (1963). Acoustic confusions and memory span for words. Nature, 197, 1029-30.

CONRAD, R. (1964). Acoustic confusion and immediate memory. Brit. J. Psychol., 55, 75-84.

HOROWITZ, L. M. (1961). Free recall and ordering of trigrams. J. exp. Psychol., 62, 51-7

THORNDIKE, E. L., and LORGE, I. (1944). The Teacher's Word Book of 30,000 Words. New York: Teachers' College, Columbia University.

UNDERWOOD, B. J. (1951). Studies of distributed practice: H. Learning and retention of paired-adjective lists with two levels of intra-list similarity. J. exp. Psychol., 42, 153

UNDERWOOD. B. J., and GOAD, D. (1951). Studies of distributed practice: I. The influence of intra-list similarity in serial learning. J. exp. Psychol., 42, 125-34.

Manuscript received 22nd February, 1966.