A Study in Two-Handed Input

Two experiments were run to investigate two-handed input. The tasks selected were chosen to be representative of common tasks found in CAD and office information systems. In the experiments, the tasks assigned to each hand involved communicating continuous, rather than discrete, information.

Experiment one involved the performance of a selection/positioning task in which the selection and positioning sub-tasks were performed by separate hands using separate transducers. Without prompting, novice subjects adopted strategies that involved performing the two sub-tasks simultaneously. We interpret this as a demonstration that, in the appropriate context, users are capable of simultaneously providing continuous data from two hands without significant overhead. The results also show that, for the experimental task, that speed of task performance is strongly correlated to degree of parallelism.

Experiment two involved the performance of a navigation/selection task. It compared a one-handed versus two-handed method for finding and selecting words in a stylized document. The results show that, for the experimental task, the two-handed method significantly outperformed the common one-handed method by a number of measures. Unlike experiment one, only two subjects adopted strategies that used both hands simultaneously. The benefits of the two-handed technique, therefore, are interpreted as being due to efficiency of hand motion. However, the two subjects who did use parallel strategies had the two fastest times over all subjects.