The effects of interruptions in work activity: field and laboratory results.

The effects of interruptions in work activity were investigated, first in a field study where the operators' task was to card-index data about customers' phone lines. The interruptions due to customers' calls resulted in an increase of the processing time of the current task and in the use of several management strategies. A laboratory study was then designed in order to study the effects of temporal strain, complexity and similarity on time-sharing efficiency and to clarify the psychological mechanisms underlying the switching from one task to the other. The results showed especially a significant effect of temporal strains on performance and a strong increase in mean error rate at the very beginning of the processing of the second task. In conclusion, advice is given for both technical and organisational design.