TWuiST: A discrete tactile-proprioceptive display for eye and ear free output on mobile devices

Proprioception -the human ability to sense the orientation of limbs without vision or hearing- is one of the main drivers of complex motor operations, which is something mobile interfaces may be able to exploit to achieve robust eye and ear free forms of interaction. This paper explores the use of proprioception as an output modality by combining kinesthetic information of a mobile device with vibrotactile feedback. A user study with 16 users explored the temporal resolution of proprioceptive displays for two different spatial resolutions with orientations (o) either defined in a space (o=6) or in a plane (o = 8). Users were able to find target orientations in 2;652 (space) and 2;638 (plane) milliseconds. The performance of discrete proprioceptive displays is comparable with more advanced forms of tactile feedback provision -but unlike these- proprioceptive displays can be facilitated using features already present in current mobile devices. Our experiences elicited a number of guidelines and tradeoffs for the design of discrete proprioceptive displays.