Retrieval Inhibition and Related Adaptive Pecularities of Human Memory

The functional properties of the human as an information-processing device differ in significant ways from the corresponding properties of the standard digital computer. One such important difference is that items in human long-term memory (e.g., names, numbers, facts) differ greatly in accessibility--that is, in the likelihood that they can be retrieved (recalled) when needed. Retrieval of information from long-term memory is erratic, probabilistic, and context dependent in ways that would seem intolerable in the search of a computer's memory. From one perspective, the unreliable nature of the retrieval of information from human memory seems nothing more than a weakness of the system. From another perspective, however, the retrieval failures we suffer are a by-product of a system that is, overall, adaptive. Given the virtually unlimited storage capacity of human memory, and the relatively slow rate of neural transmission, we do not want everything in our long-term memories to be accessible, particularly when that information is irrelevant or out of date (such as where we left the car yesterday, or the address where an important business associate used to work). We argue herein that the pattern of accessibility across items in memory changes in dynamic and adaptive ways as a consequence of input (presentation) events, output (recall) events, and shifts in environmental, social, and mood-state cues, and that inhibitory processes (and recovery over time from such inhibition) play a central role in such changes.