Processing and measures of retrieval speed to differentiate between structures of primary and secondary memory

Humans have long been interested in understanding how we process or encode information, how we store information, and how we retrieve information, the venerable memory system. Additionally, researchers have been interested in how the memory system is organized. Some researchers have suggested that the information that is relevant to a given task or goal is held in a short-term or primary memory. Some of this information eventually may make its way into long-term or secondary memory. Researchers who study memory in this fashion are often characterized as being interested in studying the structure of memory. There are other equally important questions that can be asked about memory and these involve the basic function or purpose of memory. Of course we have a memory system, but why do we have it and what is its use? The present research is interested in both a structural and functional account of memory. Based on the idea that memory is a future oriented system, a series of 6 studies were conducted to investigate the structure of human memory by comparing information processing differences (prospective functional processing instructions vs orthographic processing instructions) across traditional short- and long-term measure of memory. The aggregate evidence compiled from both between participant design (Experiments 1, 2, 5, & 6) and with-in participant design (Experiments 3 & 4) experiments suggest that both primary (short-term) and secondary (long-term) memory operates similarly across the different information processing instructions. The functional processing instructions worked to increase the speed of retrieval from primary memory relative to the orthographic processing instructions. Interestingly, this was only the case when the cognitive load (manipulated by changing set sizes to subspan and supraspan list lengths across experiments) of the primary memory task was sufficiently small and within the constraints of the capacity of the focus of attention. Even when the primary memory task was manipulated to be a complex span task (Experiments 5 & 6) the findings remained robust. The evidence largely favors an embedded processing model of memory (Cowan, 1988, 1995, 2001). Further, a discussion related to the intricacies of complex span memory tasks is advanced, suggesting particular complex span designs that use processing instructions may assist (rather than inhibit) memory retrieval.