DESIGN RECOMMENDATIONS FOR TACTONS IN TOUCH SCREEN INTERACTION

Tactons are structured tactile messages and used to transmit information to users via the tactile sense. In recent studies, tactons were tested under various conditions and their benefits were demonstrated, while tactons were mostly applied on a non-interacting part of participants' body. In future applications, e. g. in touch screen interaction, the device itself will probably generate the tactile feedback providing it to the user's interacting finger. Therefore, common parameters (i. e., frequency, amplitude, rhythm, roughness, waveform, and duration) in such a setting were examined and tested for discriminability in order to derive guidelines for tacton design in touch screen interaction. 51 participants took part in the experiment, which consisted of 98 randomized tasks. In each task, participants were presented two vibration signals via a touch screen and had to decide, whether signals were identical or different. 87 tasks comprised a comparison between different signals, while only one parameter was altered in a single comparison, and 11 control pair signals were identical. The overall recognition rate was 0.69 ± 0.15 but various combinations showed recognition rates above 90%. It became clear that some parameters are more suitable in tacton design than others. Frequency and roughness achieved the best results, involving all paired comparisons which were correctly distinguished by each participant. Distinguishable levels of parameters and design recommendations were derived from the experiment, and considerations about future tacton design are presented.