Describes a theory of human memory in which a distinction is made between 3 memory stores: the sensory register, and the short- and long-term stores. Primary emphasis is given to the processes by which information is stored in and retrieved from the long-term store, a store which is considered to be a permanent repository for information. Forgetting and related phenomena are attributed to a failure of the retrieval process, in which the search through some memory area becomes less efficient as new information is placed in it. Storage and retrieval in the long-term store are conceived of as parallel processes, one mirroring the other, and each is divided into 3 stages for conceptual clarity. The memory trace is viewed as an ensemble of information stored in some memory location, the location of storage determined largely by the components of the ensemble itself. The ability of the system to cope with diverse phenomena is demonstrated by a number of selected experimental paradigms. (2 p. ref.)