Effects of stimulus duration on the amplitude difference limen for vibrotaction.

Vibrotactile amplitude difference limens (DLs) were measured by the continuous pedestal and gated pedestal methods. In both cases, the relative DL decreased as a function of the intensity of the stimulus and the results, in most cases, could be described as a near miss to Weber's law. DLs measured by the continuous pedestal method were found to decrease substantially as a function of increases in stimulus duration over a range of 12 to 1000 ms. In contrast, DLs measured by the gated pedestal method were only slightly affected by changes in stimulus duration. It was concluded that the process of temporal summation can manifest itself in reducing the size of the DL in the continuous pedestal, but not the gated pedestal, paradigm.