A New Approach to Circumventing the Conductance-Resistance Choice: Recording of Phase Angle Between Alternating-Current and -Voltage

Abstract

Electrodermal Responses (EDRs) recorded by the exosomatic technique are usually described as either Skin Conductance Responses (SCRs in μmho units) or as Skin Resistance Responses (SRRs in kΩ units). These two measures, though transformable into each other, are not equivalent when parameters are extracted from the raw data. Response magnitude is affected by changes of tonic level in a different manner when conductance is used instead of resistance. Therefore it is difficult to compare results obtained the two methods, and the question of the more appropriate measure is discussed in the literature. However, up to now there is no satisfactory solution of that problem. In order to make results obtained from different recording techniques comparable it is necessary to express results always in the same unit. Lykken and Venables (1971) have recommended that this should be conductance. Thus, when data are obtained in resistance units by using the constant current technique, all values have to be transformed into their reciprocal before any addition or subtraction is performed. Furthermore, the subtraction of the tonic level from superimposed phasic responses by offset compensation or an alternating-current amplifier with a time constant cannot be done before transformation. Therefore, if phasic responses are recorded separately with high resolution, information on level has to be recorded additionally to enable later transformation from resistance to conductance.