The Change of speed of retrieval of items from long-term memory: Control by the parallel hazard functions in a parallel system

Classical work by Bousefield & Sedgewick in the 1940s and that by McGill in the 1960s applied what amounted to stochastic death processes with exponential interarrival times to the inter-retrieval times of times from long-term memory in free recall of items from a category. The exponential models used predicted increasingly longer inter-retrieval times over time and/or number of retrievals. We were interested in the generality of this phenomenon. Our mathematical investigations employing hazard functions, found that although this type of behavior does indeed, follow from a broad class of death processes, there exist intriguing, if perhaps unusual-in-nature, classes of hazard functions (underpinning the parallel systems) which violate this seemingly natural kind of behavior.