Interplay of Tactile and Visual Guidance Cues under Multimodal Workload

Modern user interfaces – computerized, complex and time-critical – increasingly support users who multi-task; yet to do this well, we need a better understanding of how computer-user communication degrades with demand on user attention, and the benefits and risks of introducing new display modalities into high-demand environments, Touch can be a natural and intuitive locus of information exchange and is an obvious candidate for offloading visual and/or auditory channels. In this study we compared salience-calibrated tactile, visual and multimodal navigation cues during a driving-like task, and examined the effectiveness and intrusiveness of the navigation signals while varying cognitive workload and masking of task cues. We found that participants continued to utilize haptic navigation signals under high workload, but their usage of visual and reinforced multimodal navigation cues degraded; further, the reinforced cues under high cognitive workload disrupted the visual primary task. While multimodal cue reinforcement is generally considered a positive interface design practice, these results demonstrate a different view: dual-modality cues can cross a distraction threshold in high-workload environments and lead to overall performance degradation. Conversely, our results indicate that tactile signals can be a robust, intuitive and non-intrusive way to communicate information to a user performing a visual primary task.