Audition and Speech Coding in Short-Term Memory: A Tutorial Review
Robert G. Crowder · 2022
This review covers phonological coding in short-term memory, the properties of echoic memory, and the distinction between these. Conrad’s discovery of phonologically-based confusions errors in visual memory tests, and the correlation of these confusions with confusions derived from tests of listening acuity, were the initial stimulus for hypotheses about relating speech and short-term memory. Studies of EMG responses and articulatory suppression tie these effects to the production side of speech behavior. Four recent lines of evidence show that phonological coding is not necessarily the major agent of short-term retention: (a) evidence for visual coding in “operating memory,” (b) evidence for short-term retention of phonologically identical stimulus lists, (c) evidence restricting the confusion effect to situations requiring memory for temporal order, and (d) evidence that phonological coding appears as a result of the rehearsal of information, rather than as a result of simply encoding it. Echoic memory is reserved for occasions in which stimulus information persists as sound, rather than as abstract phonological categories. Of techniques for demonstrating echoic memory, the most important are the comparison of visual and auditory presentation and the stimulus suffix effect. Whereas other interpretations for each of these two phenomena have been advanced, the fact that they depend in exactly the same way on the phonetic categories being remembered by the subjects reinforces their association with echoic memory. Even though there is imperfect closure on the properties of echoic memory and of phonological coding, the distinction between them is crucial and well-supported. In all cases, evidence for the phonological code appears independently of sequential position, whereas evidence for echoic memory is specific to recent positions.