Evaluating usability based on multimodal information: An empirical study

Abstract

New technologies are making it possible to provide an enriched view of interaction for researchers using multimodal information. This preliminary study explores the use of multiple information streams in usability evaluation. In the study, easy, medium and difficult versions of a game task were used to vary the levels of mental effort. Multimodal data streams during the three versions were analyzed, including eye tracking, pupil size, hand movement, heart rate variability (HRV) and subjectively reported data. Four findings indicate the potential value of usability evaluations based on multimodal information: First, subjective and physiological measures showed significant sensitivity to task difficulty. Second, different mental workload levels appeared to correlate with eye movement patterns, especially with a combined eye-hand movement measure. Third, HRV showed correlations with saccade speed. Finally, we present a new method using the ratio of eye fixations over mouse clicks to evaluate performance in more detail. These results warrant further investigations and take an initial step toward establishing usability evaluation methods based on multimodal information. Copyright 2006 ACM.