Vibrotactile sensitivity in active finger pressing

An experiment was performed to study the effect of actively applied forces on vibrotactile thresholds. The task consisted in pressing the fingertip against a flat rigid surface which provided broadband vibration noise of varying amplitude. Three force levels were considered, ranging from light touch to hard press. Possibly due to the concurrent effect of large contact area, spectrally complex stimuli and active pressing force, the measured sensitivity thresholds are considerably lower than what is found in most of the previous literature. Moreover, significant differences in thresholds were found between the lowest and middle force level, and the highest and middle force level.