Proximity Analysis and the Structure of Organization in Free Recall.

An experiment was designed to test the sensitivity of the method to differences in organizational structure. All subjects learned a list consisting of words selected from hierarchically related taxonomic categories, and which could be organized in alternative ways. Three experimental groups were influenced to adopt the alternative organizations by using different blocked presentation orders of the items. Twelve acquisition trials were given and long-term retention was tested after either 1, 5, 10, or 20 days. All experimental groups receiving categorically blocked presentation recalled and retained more words than a random input-order control group. However, the experimental groups did not differ among themselves in recall during acquisition or retention. The proximity analyses produced results which were consistent with the predetermined patterns of organization and indicated that the different organizations of the list were maintained in the retention test. Existing data from several studies of part-whole transfer by Ornstein were reanalyzed to assess the explanatory power of the method of proximity analysis. These studies had delineated some conditions under which prior learning of part of a list would facilitate or hinder subsequent learning of the whole list. One study demonstrated that random presentation of the whole list produced negative transfer, but that whole-list learning was facilitated by blocking the presentation order of the final list according to the “old” and “new” subsets of items. Applying proximity analysis to these data, it was found that the higher-order subjective units identified from the first-list protocols carried over to second list learning only for those subjects who had received blocked presentation of the final list. These results directly verified predictions which had been made from a theory of subjective organization (Tulving). It was concluded that the method of proximity analysis can be useful in attempts to elucidate the relationship between organization and memory. One of the central questions in the study of free recall learning concerns the role of organizational factors in retrieving information from memory. This work has been greatly facilitated by the development of procedures for measuring the amount of organization evidenced in recall. At a conceptual level, such measures may be thought of as indexing the formation of informationally-rich higher order memory units which serve as multiple access routes to the list items they subtend. Thus, a given list item may be retrieved either on its own merits or through prior retrieval of the subjective memory unit which includes it. There has been, however, no way to determine the actual manner of organization employed by individual subjects. Such a procedure would seem necessary in order to test directly hypotheses concerning the way in which organization influences performance and retention. A method for assessing the structure of organization was developed on the basis of the ordinal separation, or proximity, between pairs of items in recall protocols over a series of trials. The proximity measure is based on the assumption, common to all indices of organization, that items which are coded together in subjective memory units will consistently tend to be recalled contiguously in output. Methods of hierarchical cluster analysis are then employed to determine the structure of organization implied by the proximities between items. An experiment was designed to test the sensitivity of the method to differences in organizational structure. All subjects learned a list consisting of words selected from hierarchically related taxonomic categories, and which could be organized in alternative ways. Three experimental groups were influenced to adopt the alternative organizations by using different blocked presentation orders of the items. Twelve acquisition trials were given and long-term retention was tested after either 1, 5, 10, or 20 days. All experimental groups receiving categorically blocked presentation recalled and retained more words than a random input-order control group. However, the experimental groups did not differ among themselves in recall during acquisition or retention. The proximity analyses produced results which were consistent with the predetermined patterns of organization and indicated that the different organizations of the list were maintained in the retention test. Existing data from several studies of part-whole transfer by Ornstein (1970) were reanalyzed to assess the explanatory power of the method of proximity analysis. These studies had delineated some conditions under which prior learning of part of a list would facilitate or hinder subsequent learning of the whole list. One study demonstrated that random presentation of the whole list produced negative transfer, but that whole-list learning was facilitated by blocking the presentation order of the final list according to the “old” and “new” subsets of items. Applying proximity analysis to these data, it was found that the higher-order subjective units identified from the first-list protocols carried over to second list learning only for those subjects who had received blocked presentation of the final list. These results directly verified predictions which had been made from a theory of subjective organization (Tulving, 1966). It was concluded that the method of proximity analysis can be useful in attempts to elucidate the relationship between organization and memory.