System Usability Evaluation for Input Operation using Oculo-motors

This paper investigates the relationship between oculomotors, which consist of eye-movement and pupillary change, and the traditional subjective index for “usability”, to determine the possibility of evaluating HumanComputer Interaction (HCI). An evaluation experiment was conducted by operating a target on a computer display using input devices: mouse, keyboard and key pad. The results show there is a significant correlated relationship between the pupil size and the SU-score, which is an established subjective evaluation index for system usability. These results provide evidence that pupil size can be used as an index of the system’s usability, and also that the SUscore can be estimated from the pupil size. The indices of eye-movement, which consist of saccade frequency, saccade length and saccade time, indicate characteristics of the input operation behavior. These two results suggest that pupil size and index of eye-movement as oculo-motor indices, can provide information about a system’s overall usability regarding the input operation task. Additionally, these indices show stability even during short observation periods. This suggests that it is possible to observe temporal changes of system usability. The results provide evidence that oculo-motors can be an index of system usability.