Two-Point Discrimination of Vibrotactile Stimuli on the Forearm MHCI032

Humans can distinguish two short simultaneous touches on the forearm, called Two-Point Discrimination (2PD), starting at a distance of approximately 40 mm. However, similar insights are lacking for vibrotactile stimuli, which would be essential for designing ergonomic gesture wristbands. Thus, an oriented 2PD test was performed using vibrotactile actuators on the forearm placed around the wrist (transverse) and along the forearm (longitudinal). The results indicate that the orientation between two actuators cannot be robustly distinguished. Two simultaneous stimuli on the forearm can best be detected at 90 mm distance, with a success rate of up to 96% for transverse placement when the actuators are arranged around the wrist. In this case, the actuators are approximately placed opposite each other, looking at the wrist as a circle. Thus, an actuator arrangement around the wrist is most sufficient to distinguish between a single and two simultaneous vibrotactile stimuli.