Temporal factors in mental work: Effects of interrupted activities

Although interruptions are daily occurring events for most working people, little research has been done on the impacts of interruptions on workers and their performance. This study examines the effects of interruptions on task performance and its regulation, as well as on workers' psychological and psychophysiological state. Two parallel experiments were carried out in the Netherlands and in Russia, using a common conceptual framework and overlapping designs. Employees with relevant work experience carried out realistic text editing tasks in a simulated office environment, while the frequency and complexity of interruptions were experimentally manipulated. It was hypothesized that interruptions: (i) would cause a; deterioration of performance; (ii) evoke strategies to partially compensate for this deterioration; (iii) affect subjects' emotions and well-being negatively; and (iv) raise the level of effort and activation. It was also hypothesized that greater frequency and complexity of interruptions would enhance the expected effects. The hypotheses are only partially confirmed. The results show that, contrary to what was expected, interruptions cause people to perform the main task faster while maintaining the level of quality. Participants develop strategies enabling them to deal effectively with the interruptions, while actually, over-compensating the potential performance decline. Interruptions do have a negative impact on emotion and well-being, and lead to an increase of effort expenditure, although not to an increase in activation. Thus the improved performance is achieved at the expense of higher psychological costs. Greater complexity evoked more favourable responses among the Dutch participants and more unfavourable ones among the Russian participants. These differences are interpreted in terms of the participants' professional background. The research demonstrates that the effects of interruptions reach beyond the execution of additional tasks and the change of work strategies. Interruptions appear to have an after-effect, influencing the workers' subsequent readiness to perform. Detailed analysis of the activity in the interruption interval, focusing on cognitive processes during episodes of 'change-over' and 'resumption' support this interpretation.