Memorability as a measure of processing: a unit analysis of prose and list learning.

SUMMARY The percentage of subjects recalling each unit in a list or prose passage is considered as a dependent measure. When the same units are recalled in different tasks, processing is assumed to be the same; when different units are recalled, processing is assumed to be different. Two collections of memory tasks are presented, one for lists and one for prose. The relations found in these two collections are supported by an extensive reanalysis of the existing prose memory literature. The same set of words were learned by 13 different groups of subjects under 13 different conditions. Included were intentional free-recall tasks, incidental free recall following lexical decision, and incidental free recall following ratings of orthographic distinctiveness and emotionality. Although the nine free-recall tasks varied widely with regard to the amount of recall, the relative probability of recall for the words was very similar among the tasks. Imagery encoding and recognition produced relative probabilities of recall that were different from each other and from the free-recall tasks. Similar results were obtained with a prose passage. A story was learned by 13 different groups of subjects under 13 different conditions. Eight free-recall tasks, which varied with respect to incidental or intentional learning, retention interval, and the age of the subjects, produced similar relative probabilities of recall, whereas recognition and prompted recall produced relative probabilities of recall that were different from each other and from the free-recall tasks. A review of the prose literature was undertaken to test the generality of these results. Analysis of variance is the most common statistical procedure in this literature. If the relative probability of recall of units varied across conditions, a units by condition interaction would be expected. For the 12 studies that manipulated retention interval, an average of 21% of the variance was accounted for by the main effect of retention interval, 17% by the main effect of units, and only 2% by the retention interval by units interaction. Similarly, for the 12 studies that varied the age of the subjects, 6% of the variance was accounted for by the main effect of age, 32% by the main effect of units, and only 1% by the interaction of age by units. Moreover, although there was enough statistical power so that the unit main effects, which used the same error term as the interactions, were all significant at the .001 level, only half of the age by units interactions were significant at the .05 level. Unlike studies varying retention interval and the age of the subjects, studies varying the perspective of the reader at encoding often produced interactions larger than their main effects. Similar results were obtained for the list learning and prose studies, suggesting a continuity between these two domains. In particular, the relative probability of recall changed little when retention interval, age of subject, or depth of processing changed in standard ways. This similarity among the tasks challenges some current views of retention and of depth of processing. In both list learning and prose studies, changes in retrieval task and some changes in initial encoding led to differences in the relative probability of recall, suggesting that these manipulations affect processing. It is argued that the descriptive unit analysis approach is an efficient way to approach theory development given our current state of knowledge about human memory. This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly.