Interruptions in the Tower of London Task: Can Preparation Minimise Disruption?

Responding to computer-initiated notifications requires a shift in attention and therefore disrupts the flow of work. Two exploratory experiments investigate how this decrement can be minimised when a short preparatory time is available before switching to deal with the interrupting task. The execution phase of a computer-based Tower of London task was interrupted by the requirement to perform simple verbal reasoning problems, incurring a cost relative to continuous plan execution. The goal-activation model (Altmann & Trafton, 2002) proposes a critical time period before engaging in the interruption (the “interruption lag”) during which cues pertaining to the primary task can be encoded to facilitate subsequent task resumption. Experiment 1 demonstrated that resumption times were significantly quicker when the interruption was preceded by a three second interruption lag, and that time to complete the interrupting task was also reduced. In Experiment 2, participants chose when to engage in the secondary task. Although this did not benefit task resumption times relative to unexpected interruptions, it significantly reduced completion times on the secondary task. The results are interpreted within the framework of the goal-activation model and suggest that the interruption lag is beneficial in terms of performance on both the primary and interrupting tasks.