Depth of processing and the retention of words in episodic memory.

SUMMARY Ten experiments were designed to explore the levels of processing framework for human memory research proposed by Craik and Lockhart (1972). The basic notions are that the episodic memory trace may be thought of as a rather automatic by-product of operations carried out by the cognitive system and that the durability of the trace is a positive function of of processing, where depth refers to greater degrees of semantic involvement. Subjects were induced to process words to different depths by answering various questions about the words. For example, shallow encodings were achieved by asking questions about typescript; intermediate levels of encoding were accomplished by asking questions about rhymes; deep levels were induced by asking whether the word would fit into a given category or sentence frame. After the encoding phase was completed, subjects were unexpectedly given a recall or recognition test for the words. In general, deeper encodings took longer to accomplish and were associated with higher levels of performance on the subsequent memory test. Also, questions leading to positive responses were associated with higher retention levels than questions leading to negative responses, at least at deeper levels of encoding. Further experiments examined this pattern of effects in greater analytic detail. It was established that the original results did not simply reflect differential encoding times; an experiment was designed in which a complex but shallow task took longer to carry out but yielded lower levels of recognition than an easy, deeper task. Other studies explored reasons for the superior retention of words associated with positive responses on the initial task. Negative responses were remembered as well as positive responses when the questions led to an equally elaborate encoding in the two cases. The idea that elaboration or of encoding provides a better description of the results was given a further boost by the finding of the typical pattern of results under intentional learning conditions, and where each word was exposed for 6 sec in the initial phase. While spread and elaboration may indeed be better descriptive terms for the present findings, retention depends critically on the qualitative nature of the encoding operations performed; a minimal semantic analysis is more beneficial than an extensive structural analysis. Finally, Schulman's (1974) principle of congruity appears necessary for a complete description of the effects obtained. Memory performance is enhanced to the extent that the context, or encoding question, forms an integrated unit with the word presented. A congruous encoding yields superior memory performance because a more elaborate trace is laid down and because in such cases the structure of semantic memory can be utilized more effectively to facilitate retrieval. The article concludes with a discussion of the broader implications of these data and ideas for the study of human learning and memory,