The prevalence of tactile motion aftereffects.

The present study examined the prevalence of motion aftereffects (MAEs) in the sense of touch. The effects of two types of apparatuses were tested: a ridged, spinning cylinder and an array of vibrating tactors from the Optacon, a reading aid for the blind. In the first phase of the study, 50 subjects were tested for a total of 200 trials on both stimulators. Approximately one-third of the trials with both stimulators produced reports of MAEs in either the negative (expected) direction or the positive direction relative to the adapting stimulus. With the cylinder stimulator, there were significantly more reports of positive MAEs than negative MAEs. Subjects who reported MAEs in the first phase of the experiment were tested again in the second phase of the experiment. This additional testing produced results similar to those obtained in the first phase and did not produce a substantial increase in the number of reports of MAEs. It appears that tactile MAEs are not as readily generated as visual MAEs.