Edge vibration improves ability to discriminate roughness difference of adjoining areas

Researchers have studied the discrimination thresholds between different vibrotactile signals under various conditions. Humans cannot recognize slight differences in vibrotactile stimuli that are smaller than the perception threshold. This is a constraint in the vibrotactile design used in practical applications. This article focuses on the vibrational feedback at the 'edge' between multiple areas, while previous studies have not considered this. We assume that the edge vibration not only emphasizes the presence of the edge itself, but also has an effect on the vibrotactile perception of the adjoining areas. Specifically, we hypothesize that the edge vibration would modify the user's ability to discriminate vibrotactile differences between adjoining areas. We conducted a user study to test this hypothesis. As a result, we found that presenting edge vibrations at the boundaries between adjacent textures makes it easier to discriminate the frequency and amplitude differences of the vibrations of those uneven textures. This article could increase the flexibility of vibrotactile design, and vibrotactile designers could use these results to design a wider variety of vibrations for adjacent areas.