The “Memory Cliff” beyond Span in Immediate Recall

Abstract

Immediate recall of sub-span, span length, and supra-span memoranda was tested in 27 normal nursing students. Random series of digits and consonant letters ranging from 5 to 20 items were presented at the rate of 1 per second. Maximum recall occurred with memoranda of approximately span length, with a sharp drop of recall as span was exceeded. Absolute recall of supra-span memoranda remained at a plateau after the initial drop. The use of a special scoring method and analysis of data by reladng the results to each individual's span permitted an accurate representation of the drop in recall as span was exceeded and the constancy in recall with supra-span memoranda. It is concluded that for immediate ordered recall maximum information gain occurs for each individual at his span rather than at an arbitrary memorandum lrngth This study indirectly supports the separation of immediate memory and storage mechanisms.For many years psychologists have been interested in how much a normal S can remember when presented with memoranda2 of varying lengths. The amount remembered after a single hearing-immediate ordered recall-is commonly determined by presenting increasingly long series of digits to test S's digit span. Relatively little, however, is known about the changes in immediate recall as memorandum length is varied from below span, through span, and into the supra-span range. The clzssical view has been that immediate recall gradually decreases as memorandum length is increased beyond span (Selzer & Wickelgren, 1963 ) .One widely known swdy is that of Oberly (1928) in which he determined how often whole series were recalled without error. He found that as the length increased the percentage of series perfectly recalled gradually declined in a straight-line fashion. However, partial scores were not determined for imperfectly recalled series. Thus. the study did not show whether more or fewer digits were recalled as memorandum length increased.In another well knowr, investigation Gates (1916) determined the number of digits recalled with series of increasing length, ranging from 4 to 12 digits.Using the standard "ordered recall" scoring method, he noted that the number of digits recalled decreased as span was exceeded but concluded that the supraspan decline was a gradual and continuous one.

Age differences in everyday memory: Laboratory analogues of telephone number recall.

“…Although it has been argued that ordered recall scores capitalize on chance (Drachman & Zaks, 1967), this change in scoring methodology had no impact on our findings. Multivariate analysis showed a significant effect for age, F(2, 223) = 21.1, p <…”

Further evidence of the intricacy of memory span.

“…First, the actual number of items recalled in their order of presentation has been found to decline as list length exceeds span (Drachman & Arbit, 1966;Drachman&Zaks, 1967;Friedman, 1966;Gates, 1916;Oberly, 1928). Dubbed the "memory cliff beyond span" (Drachman & Zaks, 1967), this reversal in performance is consistent with the notion of a difference in the way span and supraspan lists are remembered.…”

Utility of digit recall tasks for assessing memory in the aged.

“…Thus, repetition of the early digits in the series would be expected to interfere with retention of subsequent digits. Scoring was accomplished using a system described by Drachman and Zaks (1967) and Drachman and Leavitt (1972). Scoring was designed to recognize as many correctly recalled items as possible while minimizing scores for chance responses by employing the following rules: (a) The first and last items were scored as correct; (b) any correct items adjacent to correct first or last items were scored as correct; and (c) all groups of three or more items whose order corresponded to a similar sequence in any location in the digit series were scored as correct.…”