Magnitude scales for electrocutaneous stimulation

The application of Stevens’s power law to the sensation resulting from electrocutaneous stimulation is reviewed. Its use for data from individual observers as well as pooled data from several observers is discussed. Magnitude estimates were obtained from 33 observers of the sensation resulting from electrocutaneous stimulation over the median nerve. Seven mathematical functions were applied to the data and tested for goodness of fit. The power function with or without threshold correction factor did not emerge as better than alternative functions. Difficulties in using the power function in studies of individual differences are reviewed. It is concluded that there is no adequate reason at present to discard the linear function in favor of more complex functions in psychophysical scaling of sensation induced by electric shock.