Line-Gap Discrimination of the Skin

In three experiments, different influences on the ability to separate stimuli on the skin or detect gaps between them were investigated. The first study presented a new method of studying gap detection which eliminates methodological difficulties inherent in the classical two-point method, and it was shown that thresholds decrease with extended practice on a given skin area. The second study investigated the ability to detect point stimuli inserted within gaps and demonstrated that the perception of such stimuli is suppressed when they are centered in gaps that are discriminable. Also, it was shown that the two-gap threshold is nearly twice the single-gap threshold, and therefore distance between edges is more important than amount of unstimulated skin for gap discrimination. In the third study, the amount of stimulation on each side of tactile gaps was varied, and it was determined that this does not significantly affect gap detection.