Vibrotactile masking: Some spatial and temporal aspects

Threshold elevations (TE) were determined for three Os at a test site on the left thigh with a masker placed singly at each of 10 widespread loei on the trunk. Although lateral changes in masker placement did not produce a significant alteration in TE (p> .10), there was a systematic decrease in TE with longitudinal separation between masker and test sites on the body. Appropriate manipulations of the time interval between masker and test signals were found effective in offsetting these decreases. It appeared that longitudinal separations were differentially affecting temporal delays by producing unequal neural distances from the test and masker sites to the CNS. There were, however, some spatial changes that could not be accounted for by temporal offsets. Thresholds at a finger test site were significantly less elevated (p< .01) by contralateral placement of maskers than by ipsilateral placement, and the particular test site chosen for threshold determinations, either index finger or thigh, determined the amount of TE.