Retrieval variability: sources and consequences.

A memory model that differentiates between active traces (ongoing electrochemical neural transmission) and passive traces (chemical/structural modification of neurons) is briefly outlined. Evidence suggests that new information is initially encoded as a passive representation within a fraction of a second, leaving little opportunity for retroactive interference with storage processes. Instead, it appears that retroactive interference results from disruption of post-acquisition processing which is necessary for subsequent retrieval. Using this hybrid cognitive-physiological framework, we examine possible sources of associative performance deficits. A distinction is made between similarity interference (arising from the content similarity of the target and interfering traces) and processing interference (arising from the competition between the two traces for use of a limited capacity processor). Both types of interference can act proactively or retroactively, and the similarity-processing and proactive-retroactive dimensions are viewed as orthogonal to the question of whether information is permanently lost or merely subject to a reversible retrieval failure. When reminder techniques (pretest cuing) are used, numerous instances of memory failure commonly identified as "acquisition failures" are found to be reversible without the occurrence of relevant new learning. This literature review constitutes the greater part of the paper. It is concluded that many memory failures are due at least in part to retrieval failure. Consideration of potential retrieval processes in light of the studies that are reviewed argues for the expansion of the initial active-passive trace distinction to three types of traces. In addition to active traces, these include two distinct types of passive traces, i.e., a small content-addressable reference catalog with innately defined dimensions that is used to locate more detailed passive traces, and a large capacity store of detailed passive traces that is location-addressable. The latter type of passive trace presumably is laid down almost instantaneously as events occur, i.e., in real time, whereas the reference catalog type of passive trace, which is used to address the detailed traces, is established somewhat after the sequence of events is complete. Hence, the reference catalog trace is more vulnerable and results in retrieval failure when it is disrupted.(ABSTRACT TRUNCATED AT 400 WORDS)