Designing mediated social touch for mobile communication: From hand gestures to touch signals

The advanced haptic technology in smartphones makes mediated social touch (MST) possible and provides rich mobile communication between people. This paper presents a generation method for MST signals on smartphones. We translate MST gesture pressure to MST signal intensity, specifically by varying frequency through a function that maps pressure to frequency. We set the duration and provide different compound waveform compositions for MST signals. We conducted two user studies, each with 20 participants. The pilot study explored how likely the designed MST signals could be understood as intended MST gestures. We screened 23 MST signals that were suitable for intended MST gestures. Then, we conducted a recognition task in the main study to explore to which extent the designed MST signals could be recognized as intended MST gestures. The recall results exhibited a range of 13.3–71.7 %, while the precision results varied from 15.1 to 55.1 %. These results can be referenced when designing MST signals. Our design implications include adjusting signal parameters to better match MST gestures and creating context-specific signals for different expressions. We suggest controlling the number of signals, using varied compound waveform composition forms, and adding visual stickers with vibrotactile stimuli. MST signals should also be evaluated in specific contexts, especially for mobile communication.