Abstract:

Subjects estimated the subjective magnitude of roughness and the size of steel balls by the method of absolute magnitude estimation. Using the index finger and thumb, estimates were made of 11 grades of sandpaper with particle diameters ranging from 16--905 (mu)m. The results describe a power function and show spatial summation when stimuli are applied simultaneously to two sites (finger and thumb). The same subjects judged the size of nine steel balls ranging in diameter from 0.4--6.4 mm. Estimates were made with combinations of the index finger, volar forearm, and thumb. Again, all of the results were power functions and spatial summation of tactile stimulation was evident. The results are discussed in terms of theoretical considerations and practical application. [Work supported by Unilever and NIH, PO1DC00380].