Previous studies of event-based prospective memory have demonstrated that the character of an ongoing task can affect cue detection. By contrast, this study demonstrated that there is a reciprocal relationship insofar as cue-verification and response-retrieval processes interfered with making a response in the ongoing task. The amount of interference was determined by the type of intention, which was manipulated to affect the complexity of verification and retrospective response retrieval. These relationships were true even when the interference caused by cue detection was separated from a more general effect to ongoing-task performance caused by shifts in attentional allocation policies. The results have theoretical implications for models that attempt to specify the cognitive microstructure of event-based prospective memory.

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One of the many important functions of memory is to store intentions about future plans, goals, and activities. Intending to refill a prescription, planning a trip to the grocery store, setting aside a future time to write, read, or work on a hobby, or forming the intention to give someone a piece of information are everyday examples of what has been termed prospective memory in the scientific literature. The label connotes a forward-looking component to the memory, and it was intended to contrast directly with retrospective memory, for activities and events that occurred in the past. Although people form a vast array of prospective memories that vary along many dimensions (see Kvavilashvili & Ellis, 1996), perhaps the most often cited distinction contrasts event-based with time-based prospective memory (see, e.g., Einstein & McDaniel, 1990;Park, Hertzog, Kidder, Morrell, & Mayhorn, 1997). In event-based prospective memory, people allow an environmental cue to remind them to complete an intention. For example, the sight of a convenience store might bring to mind the intention to replenish milk, or the sight of a friend might trigger t he intention to relate a novel story. In time-based prospective memory, people plan to execute an activity either at a predetermined time, such as attending a meeting at work, or after a specific period of time has elapsed, such as taking food out of the oven before it is overcooked. Despite the fact that neither type of intention is more or less important than the other, event-based prospective memory has received much more scientific scrutiny than time-based memory (see . Consequently, the theories concerning event-based memory are more developed, as are the various laboratory techniques used to study it.The present study explores a timely issue in the field of prospective memory-namely, the degree to which possessing a prospective memory interferes with an ongoing activity. In standard laboratory instantiations of eventbased tasks, people are engaged in a cognitive activity such as rating words on various dimensions, naming pictures of famous faces, performing a lexical decision task, reading a passage, and so forth (see, e.g., Ellis, Kvavilashvili, & Milne, 1999;Marsh, Hicks, & Watson, 2002;Maylor, 1996Maylor, , 1998McDaniel, Robinson-Riegler, & Einstein, 1998). Prior to commencing the task, they are asked to respond to a cue, such as a specific word or a class of items (e.g., words denoting animals), with a special action that indicates they remembered their intention. This laboratory paradigm is intended to simulate real-world situations in 1037Copyright 2006 Psychonomic Society, Inc.We thank Meghan Coyle, Austin Cope, Becky Swint, and Mandy Howard for their dedicated help in collecting the data. Correspondence concerning this article should be addressed to R. L. Marsh, Department of Psychology, University of Georgia, Athens, GA 30602-3013 (e-mail: rlmarsh@uga.edu). One of the current issues in the field of prospective memory concerns whether having an intention produces a co...

In recent theories of event-based prospective memory, researchers have debated what degree of resources are necessary to identify a cue as related to a previously established intention. In order to simulate natural variations in attention, the authors manipulated effort toward an ongoing cognitive task in which intention-related cues were embedded in 3 experiments. High effort toward the ongoing task resulted in decreased prospective memory only when the cognitive processing required to identify the cue was similar to the cognitive processing required to complete the ongoing activity. When the required processing was different for the 2 tasks, cue detection was not affected by manipulated effort, despite there being an overall cost to decision latencies in the ongoing tasks from possessing the intention. Resource allocation policies and factors that affect them are proposed to account for ongoing vs. prospective memory task performance.

Task interference occurs in prospective memory tasks when an intention deleteriously affects performance on an ongoing activity in some way. Several studies have shown that task interference can manifest itself in slower latencies to perform an ongoing task. Recent evidence demonstrates that associating intentions to certain performance contexts affects prospective memory performance (see, e.g., . In the present study, an intention was associated with a particular stimulus class, such as pictures or words. We found that task interference could be reduced when participants could reliably predict that the material about to be processed was irrelevant to the intention. This material-specific interference effect was found on a trial-by-trial basis in a random sequence of two different kinds of materials across two experiments and with blocking manipulation in another experiment. These results demonstrate that task interference is not a monolithic construct; rather, it results from dynamic and flexible attentional allocation strategies that can change on a trial-by-trial basis.