ON SPATIAL SUMMATION IN THE TACTUAL SENSE A psychophysical and neurophysiological study

F ranzén , O. On spatial summation in the tactual sense. A psychophysical and neurophysiological study. Scand. 1. Psychol ., 1969, 10, 193–208 .—Individual magnitude estimation scales of apparent intensity of a 300 c/s vibration applied to the volar aspect of the finger-tip as a function of displacement and the number of fingers stimulated were obtained. Spatial summation seems to take place with a lawful increase in perceived intensity as two and three adjacent sensory channels are excited at the same time. Median nerve compound action potentials following electrical stimulation of the index and middle fingers were recorded. A mathematical model is presented to describe and predict spatial summation. The results are interpreted in terms of funneling action of nervous tissue.