Retrieval in prospective memory: Multiple processes or just delay?

In prospective memory (PM) research, a common finding is that PM accuracy is greater using focal, rather than nonfocal, cues. Under the multiprocess framework, the high PM performance for focal cues (cues that facilitate noticing of the target), often in the absence of task interference, reflects people's ability to rely on spontaneous retrieval processes. By contrast, nonfocal cues (cues that do not facilitate noticing) require monitoring. A competing explanation suggests that a single process underlies focal versus nonfocal PM: People adjust their delay in ongoing responding to allow enough time for PM information to reach awareness (delay theory). Participants' lower nonfocal performance arises because they fail to delay responding to a sufficient degree; with focal cues, the PM information accumulation rate is fast enough that no delay is necessary (and thus most everyone performs well). We sought to improve nonfocal PM performance by pairing a PM task with fast information accumulation to an ongoing task for which the requisite information accumulated more slowly. Reasoning from delay theory, we expected PM accuracy levels in this nonfocal PM task to approximate that observed in a focal PM task (for which the PM tasks were identical). In contrast to this expectation, the focal condition displayed significantly higher PM accuracy (despite demonstrating a reliably shorter response delay). In light of these findings, we concluded that the multiprocess interpretation is favoured.