Development of a system usability assessment procedure using oculo-motors for input operation

摘要

This paper investigates the relationship between oculo-motors, such as eye-movement and pupillary change, and the conventional subjective “usability” index, using time-domain and frequency-domain approaches, with the objective to determine the possibility of evaluating interaction through oculo-motors. An evaluation experiment was conducted by operating a target on a computer display using mouse, keyboard and key pad as input devices. The results show that there is a significant correlation between pupil size and SU-score, which is an established subjective evaluation index for system usability. Cross spectrum densities (CSD) between horizontal and vertical eye-movements and coherence as standardized CSD also significantly correlate with the results of the SU-scores and error rates. To determine the frequency range of CSD and coherence for usability assessment, frequency components used as factors were extracted using factor analysis. According to the correlation coefficients between these and the performance of factor scores for predicting the conventional metrics, factor scores of CSD are better indices for assessing usability than factor scores of coherence. These two results suggest that pupil size and index of eye-movement as oculo-motor indices based on time-domain and frequency-domain approaches can provide information about a system’s overall usability regarding the input operation task.