The relative importance of suboperations of prospective memory

An event-based and a time-based prospective memory (PM) task, a script generation task, several working memory tasks, an incidental retrospective memory task, and a screen clock were implemented on the computer in one integrated procedure lasting between one and two hours. The procedure was designed to simulate four working days and four nights for a white-collar employee. Sixty-eight normal participants completed the task. Time-based prospective memory (self-injecting and going to bed at preordained times of day) shared unique variance with clock checking, but hardly at all with incidental retrospective memory. On the other hand, event-based prospective memory (answering a faint telephone cue as quickly as possible) shared unique variance with incidental retrospective memory of formally task irrelevant context and less with clock checking. The latter correlational dissociation of event-based versus time-based PM by retrospective memory reached significance, inspiring the idea that administrative versus clerical work might each impose its own type of PM demands. In both types of PM, low-level abilities (use of external aids and incidental encoding of context, respectively) seem to be critical for good performance, more so than for high-order executive functions. Our software is offered to the readership to explicitate these findings further or for other research pursuits.