Performance Sharing in an Audio-Visual Vigilance Task

The phenomenon of performance sharing, discovered in an earlier experiment, was verified in the present one, and attributed to differences in signal detectability when two vigilance tasks are performed concurrently. Performance on a vigilance display presenting easily detectable signals was shown to be enhanced by requiring the observer to monitor simultaneously another display, presenting difficult signals via a different sensory modality. Several theoretical approaches to the explanation of the phenomenon are discussed, and implications for display design and research are suggested.