Dwell, a well-known mode-switching method, is generally considered inefficient due to a requiring long dwelling time in order to avoid unintended input and also limited single mode it allows. This paper presents Dwell+ˋ, a method that boosts the effectiveness of typical dwell select by augmenting the passive dwell duration with active haptic ticks which promptly drives rapid switches of modes forward through the user’s skin sensation. This way, Dwell++ enables multi-level dwell select using rapid haptic ticks. To select a mode from a button, users dwell-touch the button until the mode of selection being haptically prompted.
Our haptic stimulation design consists of a short 10ms vibrotacile feedback that indicates a mode arriving and a break that separates consecutive modes. We first tested the effectiveness of 170ms 150ms, 130ms, 110ms intervals between modes for a 10-level selection. The results reveal that three-beat-per-chunk rhythm design, e.g., displaying longer 25ms vibration at the first of every three modes, could potentially bring higher accuracy.
The second user study reveals significant improvement where a 94.5% accuracy was achieved for a 10-level dwell++ select using the 170ms interval with 3-beat-per-chunk design, and a 93.82% accuracy using the faster 150ms interval with similar chunks for 5-level selection.
The approximate performance of conducting touch and receiving vibration from different hands was investigated at the last study for providing a wider range of usage for Dwell++.