Multi-Tasking in Human-Computer Interaction
Wolfram Boucsein and Florian Schaefer
Physiological Psychology, University of Wuppertal, Germany
Inadequate temporal structures in human-computer interaction constitute a major source of psychophysiological stress-strain processes ( Boucsein 1999). This has been repeatedly demonstrated by our group while investigating the adverse effects of system response times for more than a decade. The term system response time refers to temporal delays caused by both hardware and software features of the computer system. Prolonged system response times may not only reduce work efficiency, they may also impose severe stress on the user, as shown in physiological and subjective measures ( Kuhmann 1989). Although computers have become incredibly fast, temporal delays in humancomputer interaction continue to be a problem. Increases in hardware speed are often jeopardized by bulky software packages, time-consuming input and output devices, extensive network functions, and huge data banks to which many users may have access simultaneously.
An additional resource for coping with stress-strain processes induced by system response times may be using the multi-tasking capabilities of modern computer systems. Instead of merely waiting for the computer to respond, the user may decide to work on several processes simultaneously. However, if system response times do not exceed a certain duration, the benefit from switching to another task instead of waiting may be more than outweighed by the additional mental load that results from scheduling. The term scheduling refers to the need for organizing the work flow of different tasks running in parallel. Maintaining an optimal scheduling is an additional mental challenge for the user and thus becomes another source of stress. Coping with this type of stress can be facilitated by providing appropriate feedback on the temporal aspects of processes running in the background while a main task is performed. Therefore, process indicators play an important role in multi-tasking systems.