Applying the Cumulative Fatigue Model to Interaction on Large, Multi-Touch Displays

Large touch displays have long been studied in the lab, and are beginning to see widespread deployment in public spaces. However, a common limitation is fatigue -- often called 'gorilla arm' -- that prevents users from working with large displays for extended periods of time. A first step towards addressing fatigue is quantifying it, and while methods have been developed to quantify users' fatigue in mid-air interactions, there remains little understanding of fatigue on touch-based interfaces. To address this gap, we evaluated the accuracy of Jang et al.'s mid-air Cumulative Fatigue model for touch interaction tasks on a large display. We found that their model underestimates subjective fatigue for multi-touch interaction, but can provide accurate estimates through fine-tuning of model parameters. We discuss the implications of this finding, and the need to further develop tools to evaluate fatigue on large, multi-touch displays.