Delayed Haptic Feedback to Gaze Gestures Jari Kangas, Jussi Rantala, Deepak Akkil, Poika Isokoski, P¨ aivi Majaranta, and Roope Raisamo Tampere Unit for Computer-Human Interaction School of Information Sciences University of Tampere, Finland Abstract. Haptic feedback can improve the usability of gaze gestures in mobile devices. However, the benefit is highly sensitive to the exact timing of the feedback. In practical systems the processing and trans- mission of signals takes some time, and the feedback may be delayed. We conducted an experiment to determine limits on the feedback delays. The results show that when the delays increase to 200 ms or longer the task completion times are significantly longer than with shorter delays. Keywords: gaze tracking, gaze interaction, haptic feedback 1 Introduction Haptic feedback is typically used with mobile devices when input is provided via touch (e.g., tactile feedback of virtual keyboard) or when information is presented without an explicit input (e.g., tactile alerts). In addition to these established use cases, gaze-based interaction on a mobile device provides novel opportunities for the use of haptics. The Eye Tribe Tracker 1 is an example of a commercially available gaze tracker that can be attached to mobile devices. There has also been recent progress in building affordable head mounted gaze trackers [1]. Such technology enables gaze-based interaction when input via touch is not feasible. This can be the case with large touchscreen devices that are hard to operate using a single hand. The conventional way to use gaze for input is to fixate the gaze to an on- screen object for a pre-defined dwell time. However, this is difficult with mobile devices because objects on the displays tend to be small and the device is often slightly moving [2]. A better match for mobile interaction could be the use of gaze gestures that are suitable for interaction with small screen objects and also more tolerant to small calibration shifts and camera movements [2–4]. We have started investigating the use of haptic feedback with gaze gestures. An existing challenge in the use of gaze gestures is to provide sufficient feedback of the use, but traditionally used visual and auditory channels (see, e.g., [5]) are not optimal. Visual feedback may be difficult to perceive during eye movements and auditory feedback is not suitable for private interaction or noisy environments [6]. 1 See https://theeyetribe.com/products/