Vibrotactile Stimuli are Perceived More Intense at the Front than at the Back of the Torso

Vibrations effectively transmit information from objects, surfaces or events to the human skin through the cutaneous sense. However, due to the diverse densities of receptive fields and mechanoreceptor populations vibrotactile sensitivity differs across body parts. Hardware that utilizes vibrotactile information should consider such differences. Here, we examined perceived intensity of vibrotactile stimuli applied to the front and back of the human torso. Participants wore a vibrotactile vest. They had to judge if a vibration from the back side of the vest was larger or smaller than a fixed vibration given from the front side; the intensity of the stimulus at the back was adapted using staircase methods. We found that, stimuli at the back had to be physically more intense by 12.3% than stimuli at the front to be perceived equally intense: Presentation of vibrotactile information through wearables could equalize for differential sensitivity, e.g., to equalize attention-capturing effects.