Perceptual properties of vibrotactile material texture: Effects of amplitude changes and stimuli beneath detection thresholds

We investigate the perceptual properties of vibro-tactile material textures: in particular, the effects of changes in vibrotactile amplitudes and of vibratory stimuli that are beneath detection thresholds. Existing knowledge of the perceptual properties of vibrotactile gratings does not hold for vibrotactile material textures because material textures are composed of many more frequency components than those of grating textures. We experimentally investigate perceptual properties of wood and sandpaper textures through lossy data compression of the textures. Lossy data compression is suitable for manipulating many independent variables of material textures while maintaining their qualities. By quantization of vibratory amplitudes, we find that subjective quality of textures does not change until the number of quantization steps reaches 12. This represents that data sizes of material textures are reduced by up to approximately 75% while maintaining their qualities. By cutting off the frequency components whose amplitudes are beneath the shifted-threshold curve, we find that even subliminal stimuli affect perception. Developers of vibro-tactile material textures should be aware of these perceptual properties.