Identification and Information Transfer of Multidimensional Tactons Presented by a Single Vibrotactile Actuator

Techniques designed to deliver information to users via the haptic channel often make use of multiple actuators spread over different body locations, sometimes employing multiple haptic modalities (e.g., vibration, skin stretch, temperature) in parallel. Instead, we sought to determine the information transfer capacity of a single vibrotactile actuator. To do so, we designed 90 multidimensional tactons using four parameters: the number of pulses, tempo, frequency, and amplitude, based on prior literature and results of pilot studies. We conducted a two-day experiment with 12 participants, which evaluated their accuracy in identifying each parameter and estimated the information transfer (IT) under continuously repeating and one-shot tacton presentation schemes. Participants achieved identification a ccuracy o f i ndividual p arameters of approximately 70% for tempo, frequency, and amplitude, while their identification accuracy for number of pulses reached 90%. Although the overall tacton identification a ccuracy w as only 34.12% and 38.66% for continuous and one-shot presentations, respectively, the high dimensionality of these tactons resulted in an estimated information transfer of 3.06 bits (for one-shot presentation), the highest IT achieved to date using only a single actuator. We provide a detailed analysis of these results, and drawing from the experiment, present guidelines for multidimensional tacton design.