Group structure, coding, and memory for digit series

Recognition and recall of digit series were studied as a function of segmental groupings imposed on the series either by the location of pauses or in the naming of successive numerical groups, e.g., 1735 was read to S as "seventeen, thirty-five." Experiments show that alteration of group structure of the same underlying digit string severely degraded memorial recognition of its repetition and that the normal improvement in immediate recall with repetition was annihilated by changing groupings at each presentation. Although a second presentation of a string with altered groupings is not recognized as a repetition of its earlier occurrence, this event is equivalent to an exact repetition when they are assessed by 5"'s later ability to. recognize an ungrouped version of the underlying string. Repetition with the same groupings establishes one strong trace, whereas repetition with changed groupings establishes two weak traces either of which may mediate recognition of the uncoded version of the string. The "reallocation" hypothesis was proposed as a summary of these results, whereby group structure affects perceptual coding, which determines "where" the trace of the event is stored. This was contrasted to a "bin" hypothesis for serial recall. Experiments to differentiate these involved recall of strings in which only a subsequence or portion recurred. As predicted by the reallocation hypothesis, recall of the recurrent constant chunk improved only when it was located at the beginning of the string.