Rest is best: the role of rest and task interruptions on vigilance.

We examined the impact task interruptions have on visuospatial vigilance in two experiments. In the first experiment participants were randomly assigned to one of three interruptions: participants were given a complete rest (rest), participants completed an alphanumeric vigilance task (letter), or participants performed the primary vigilance task (continuous). In the second experiment participants were randomly assigned to one of the conditions from the first experiment or to two further conditions, in which participants (spatial memory) performed a spatial match to sample task, or participants (verbal memory) performed a letter match to sample task. Vigilance performance post-interruption was best for rest, worst for continuous, and varied for the other interruption tasks. Overall, the results suggest the vigilance decrement is due to the repeated use of particular executive resources, but there may, in addition be domain specific interference when the primary task and activities during a break make use of the same resources.