Preparing to resume an interrupted task: effects of prospective goal encoding and retrospective rehearsal

Abstract

We examine people's strategic cognitive responses to being interrupted while performing a task. Based on memory theory, we propose that resumption of a task after interruption is facilitated by preparation during the interruption lag, or the interval between an alert to a pending interruption (e.g. the phone ringing) and the interruption proper (the ensuing conversation). To test this proposal, we conducted an experiment in which participants in a Warning condition received an 8-s interruption lag, and participants in an Immediate condition received no interruption lag. Participants in the Warning condition prepared more than participants in the Immediate condition, as measured by verbal reports, and resumed the interrupted task more quickly. However, Immediate participants resumed faster with practice, suggesting that people adapt to particularly disruptive forms of interruption. The results support our task analysis of interruption and our model of memory for goals, and suggest further means for studying operator performance in dynamic task environments.

Introduction

Consider a typical interruption. You are in conversation with a colleague when the phone rings. How do you respond? You might excuse yourself for a moment, pick up the phone and quickly reschedule the caller (“I’m in a meeting; can I call you back?”), then resume the interrupted conversation. If you were expecting a long and important call, you might instead reschedule your colleague (“Can I find you in your office in 20 min?”), and then simply take the call. In either case, you have taken explicit measures to prepare to resume a task (your conversation with your colleague) that was interrupted. This particular example, in which a ringing phone signals an upcoming interruption, represents a pattern that seems to be quite general. Even in an emergency, like an alarm that is not simply a drill or a prank, one might first hurry to save all modified files and only then evacuate the building.

In this paper, we offer a simple task analysis of interruptions, focusing on the preparatory opportunity afforded by the interruption lag, or the interval between an alert (e.g. the phone ringing) and the interruption proper (e.g. the phone call). We then offer a theoretical basis for supposing that people do in fact engage in preparatory cognitive activity during the interruption lag, activity analogous to the social negotiation with your colleague in the example above. We then present an experiment that supports the prediction and helps to show how people prepare—prospectively, by encoding specific goals to achieve at time of resumption, and retrospectively, by rehearsing state information from the point of interruption. Finally, we discuss future research and applications suggested by these findings.