Pulse Number Discrimination in Tactile Spatio-Temporal Patterns

Spatio-temporal patterning effects on tactile temporal numerosity discrimination were examined. Trains of 4 to 17 mechanical “taps” were delivered successively at rates of 6, 9, or 12/sec. to the finger tips of each hand (thumbs excluded) according to 8 different spatial pattern types. 4 highly trained Ss were instructed to report only the number of signals counted in each train. Pattern type exerted a significant affect on signal number judgments at rates of 9/sec. and 12/sec. but not at 6/sec. The number of signals in a train was assessed most accurately when presented in patterns possessing a predictable spatial ordering. Results indicated that absolute judgments of the number of successive tactile signals delivered to several spatially discrete loci is dependent upon the total spatio-temporal pattern and that tactile temporal numerosity discrimination must be specified in terms of the successive and configurational aspects of a patterned array of inputs.