Discrepancy-plus-search processes in prospective memory retrieval

In the present study, we investigated the processes underlying prospective memory (PM) retrieval, focusing specifically on two possible spontaneous processes: discrepancy-plus-search and familiarity. Discrepancy was elicited by orthogonally manipulating the processing difficulties of the PM targets and the nontargets. Participants performed a PM task while solving anagrams with two levels of difficulty (easy or difficult). Assuming that the ease of processing easy anagrams would heighten a sense of familiarity, the familiarity view predicted better PM performance with easy anagrams as the PM targets. In contrast, the discrepancy-plus-search view predicted higher PM performance for the PM targets that were anagrams whose difficulty level mismatched that of the surrounding nontargets, as compared to PM targets whose difficulty matched that of the surrounding nontargets. This prediction was based on the idea that mismatching rather than matching difficulty levels would create discrepancy, thereby signaling significance for the target. Participants were more likely to perform the PM task for PM targets that were discrepant, supporting the discrepancy-plus-search view.