Perceptual Localization Performance of the Whole Hand Vibrotactile Funneling Illusion

Funneling illusion refers to a midway perceived illusory tactile sensation between multiple distant stimulations. Since haptic illusion provides guidelines to simplify tactile interfaces, funneling illusion has been explored on different parts of human skin. This study aimed to evaluate the perceptual localization performance of vibrotactile funneling illusion on palmar side of the hand. It is based on the idea of leveraging the vibrotactile funneling illusion to produce distributed vibrotactile stimuli across the entire hand using only a few vibration actuators. By designing a glove with actuators on five fingertips and the palm heel, we measured the localization density of funneling illusion on the whole hand in two experimental conditions [one-dimensional (1D) illusion along each finger and 2D illusion on palmar plane]. The results showed that the average correct rate of location discrimination was 97%, 82%, and 71% in 3-, 4-, and 5-location densities for 1D illusion and 85%, 70%, and 58% in 11-, 16-, and 21-location densities for 2D illusion, respectively. These findings confirmed the feasibility of simulating multi-location stimuli using only a few actuators. Also, perceptual guidelines were provided for the designing of vibrotactile gloves by leveraging the entire hand funneling illusion.