STEP: Acoustic Confusions in Immediate Memory [35091]

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Experiment Author: Conrad, R. Adapted from STEP and used with permission of Brian MacWhinney

Experiment Description

Participants are presented with series of letters and then asked to recall them immediately. Their mistakes tend to be systematic and related to the sound of the original letter. The letters are recorded in a confusion matrix at the end of the experiement. At the current number of trials, the matrix may not be useful, but it is possible to add more trials to increase the number of data points for the matrix.

Experiment Instructions

Participants will be presented six consecutive letters. Each letter appears for 750 milliseconds. After each string of letters participants are asked to recall the letters and use their keyboard to answer. The trial is repeated 24 times and participants will be presented 128 total letters.

Experiment Citation

Conrad, R. (1964). Acoustic confusions in immediate memory. British Journal of Psychology, 55, 75-84.

Experiment Abstract or Original Experiment Abstract

Sequences of 6 letters of the alphabet were visually presented for immediate recall to 387 subjects. Errors showed a systematic relationship to original stimuli. This is held to meet a requirement of the decay theory of immediate memory.

The same letter vocabulary was used in a test in which subjects were required to identify the letters spoken against a white noise background. A highly significant correlation was found between letters which confused in the listening test, and letters which confused in recall.

The role of neurological noise in recall is discussed in relation to these results. It is further argued that information theory is inadequate to explain the memory span, since the nature of the stimulus set, which can be defined quantitatively, as well as the information per item is likely to be a determining factor. 

Works Cited by the Experiment

Brown, J. (1959). Information, redundancy and decay of the memory trace. In The mechanisation of thought processes. Nat. Psys. Lab. Symp. No. 10, H.M.S.O.
 
Clarke, F.R. (1957). Constant ratio rule for confusion matrices in speech communication. J. Acoust. Soc. Amer., 29, 715-20.
 
Conrad, R., & Hille, B.A. (1957).Memory for long telephone numbers. P.O. Telecomm. J., 10, 37-9.
 
Crossman, E.R.F.W. (1960). Information and serial order in human immediate memory. Information Theory. London: Butterworth.
 
Curry, E.T., Fay, T.H., & Hutton, C.L. (1960). Experimental study of the relative intelligibility of alphabet letters. J. Acoust. Soc. Amer. 32, 1151-7.
 
Eccles, J.C. (1961). The effects of use and disuse on synaptic function. In Brain mechanisms and learning. Oxford: Blackwell.
 
Hebb, D.O. (1961). Distinctive features of learning in the higher animal. In brain mechanisms and learning. Oxford: Blackwell.
 
Miller, G.A. (1956). The magical number seven plus or minus two; some limits of our capacity for processing information. Pscyhol. Rev. 63, 81-97.
 
Moser, H.M., & Fotheringham, W.C. (1960). Number telling. Tech. Rep., no. 58, RF Project 1080, Ohio State Research Foundation.
 
Pollack, I. (1953). Assimilation of sequentially encoded information. Amer. J. Psychol. 66, 421-35.
 
Russell, W.R. (1959). Brain. Memory Learning. Oxford: Clarendon Press.
 
Woodworth, R.S. (1938). Experimental Psychology. New York: Henry Holt.