Imposed vibration influences perceived tactile smoothness

According to the duplex theory of tactile texture perception, detection of cutaneous vibrations produced when the exploring finger moves across a surf ace contributes importantly to the perception of fine textures. If this is true, a vibrating surface should feel different from a stationary one. To t est this prediction, experiments were conducted in which subjects examined two identical surfaces, one of which was surreptitiously made to vibrate, a nd judged which of the two was smoother. In experiment 1, the vibrating sur face was less and less often judged smoother as the amplitude of (150 Hz) v ibration increased. The effect was comparable in subjects who realized the surface was vibrating and those who did not. Experiment 2 showed that diffe rent frequencies (150-400 Hz) were equally effective in eliciting the effec t when equated in sensation level (dB SL). The results suggest that vibrota ction contributes to texture perception, and that, at least within the Paci nian channel, it does so by means of an intensity code.