Speech versus keying in command and control: effect of concurrent tasking

As a result of Poock's influential work in the early 1980s, command and control is generally believed to be one specific application where speech input holds great advantages over keyed data entry. However, a recent paper (Damper & Wood, 1995 “Speech versus keying in command and control applications ”, International Journal of Human-Computer Studies, 4 2 ,289-305) has questioned this interpretation of Poock’s data because the experimental conditions seemed to bias the results against keyed entry. While Damper and Wood modelled their experiments on Poock's, however, there were important differences which mean that their conclusions are uncertain. The objective of the work reported here was to determine if the major difference-the omission of concurrent, secondary tasking from their study-could explain Damper and Wood's observed superiority of keying over speech. Simulated command and control experiments are described in which speech input, abbreviated command keying and full command keying are compared under dual-task conditions. We find that speech input is no faster (a nonsignificant 1.23% difference) and enormously more error-prone (1038%, highly significant) than abbreviated keying for the primary data entry task, but allows somewhat more (11.32%, not significant) of a secondary information-transcription task to be completed. Full keying has no advantages whatsoever: we believe that this confirms the methodological flaw in Poock's work. If recognizer errors (as opposed to speaker errors) are discounted, however, speech shows a clear superiority over keying. This indicates that speech input has potential for the future-especially for high workload situations involving concurrent tasks-if the technology can be developed to the point where most errors are attributable to the speaker rather than to the recognizer.