The Effects of Initial Levels of Sweat Duct Filling and Skin Hydration on Electrodermal Response Amplitude

ABSTRACT The many problems encountered in efforts to demonstrate conformance of electrodermal responses with the Law of Initial Value have been thought by Lykken and Venables to stem in part from the operation of independent central and peripheral factors. This study was an attempt at separate examination of the peripheral determinants of initial value effects using animal preparations in which the central component was interrupted. Standard electrical stimuli to sympathetic nerves were used to assess the effect of various procedures calculated to change the hydration of the corneum or to change the initial level of sweat in the ducts. Drying of the corneum can cause a marked potentiation in SRR amplitude. Increase in initial degree of duct filling does likewise. These findings are consistent with a circuit model that emphasizes the shunting effect of the corneum on the contribution of ductal resistance changes to total resistance change. Effects on SCR amplitude are more complex. The complicating effect of immediately prior activity on initial value relationships calls for considerable caution in the design and interpretation of behavioral studies that involve electrodermal measurement.