Lecturer's Précis - Sperling (1963)

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First published online 07:57 BST 12th June 2002, Copyright Derek J. Smith (Chartered Engineer). This version [HT.1 - transfer of copyright] dated 12:00 13th January 2010


Sperling (1963)

See firstly the supporting commentary for this material, and Sperling (1960).

Having achieved rapid academic fame with his earlier work on iconic memory, Sperling went on to consider the memory processes which might be involved when subjects took part in his partial report experiments. He was particularly intrigued by the fact that after an initial period of rapid iconic decay lasting typically around half a second, subjects could delay their report for at least a further 30 seconds without further loss of content taking place, and he explained this by proposing that the longer response delays allowed subjects to bring their auditory memories into play to support their visual memories. Specifically, they seemed to be rehearsing their answers prior to giving them, by "saying the letters to oneself" and by then "hearing the rehearsed letters". In fact, Sperling identified "at least three" streams of information able to benefit from auditory storage, namely (a) actual auditory input, (b) rehearsal by inner speech, and (c) auditory output from the scanning process itself (because "it is assumed that observers hear themselves make a verbal response as they scan"). This is an historically significant proposition, because one of the major themes of all subsequent psycholinguistic research has been to explain this constant recoding, re-routing, and recycling of mental content. Here is the explanatory model Sperling proposed in 1963. An improved version may then be found in Sperling (1967), and the outcome of 15 years of further improvement may be found in Ellis (1982).


Sperling's (1963) Memory Model: This diagram gives a left-to-right representation of the flow of information during the task of writing down the characters identified in a brief visual display, provided time is allowed for auditory rehearsal. Three processes are identified, namely VIS, the process of visual perception, R, the process of rehearsal, and AIS, the process of auditory perception. VIS makes the iconic trace available to be "scanned", and the scanning process proceeds at a rate of one character every 10 msec. (Sperling shows a second, dotted, arrow at this point to represent the fact that it takes this finite amount of time to extract each new character from the icon). Output from the scanning process is then recoded into auditory form by R, but this recoding proceeds at a rate of about 100 msec. per character, so it cannot keep up with the much faster visual scanning process. The recoded string can be used to produce an immediate Response (response arrow at top) if required. Unscanned letters simply never get processed (indeed, it is by reducing the number of stimuli lost in this way that the partial report method achieves its success). If a response is not immediately required, R passes the rehearsal string to AIS, which can itself re-stimulate R via the lower feedback loop (shown blue). The Sound input arrow (top right) reflects the fact that AIS is also activated by externally sourced sounds, not just by inner speech, and the dotted line between Response and Sound indicates that an overtly spoken response would itself generate a sound input.


Redrawn from a black-and-white original in Sperling (1963; Figure 6). This version Copyright © 2002, Derek J. Smith.



Sperling, G. (1963). A model for some kinds of visual memory tasks. Human Factors, 5:19-31.