Response Modalities and Time-Sharing Performance

Abstract

The recent development of speech technology has provided an opportunity for new approaches in display/control design. Some researchers have proposed that the use of speech can reduce resource competition with manual controls and improve multi-task performance. However, it has also been suggested that due to the heavy reliance on within-subject experimental designs, the research supporting the resource competition hypothesis was potentially contaminated by asymmetric transfer. The present study examined the value of speech responses as a control device in a dual-task experiment. The experimental design permitted the evaluation of asymmetric transfer effects. Despite numerous significant effects supporting the advantage of mixing manual and speech responses there was no statistically significant finding that suggested the occurrence of asymmetric transfer. Also, the value of speech output was demonstrated in between-subject analyses that were logically immune to asymmetric transfer effects. Therefore, although the possibility of asymmetric transfer remains a legitimate experimental design concern, it is not a sufficient explanation for the observed response modality effects. The present results supported the resource competition hypothesis of response modality effects, and suggested that in operational environments the judicious use of speech technology can enhance performance.