Electrodermal Recovery and Stimulus Significance

The validity of Edelberg's (1970) hypothesis that speed at which the electrodermal response (EDR) recovers is affected by meaning of the stimulus evoking it, has been challenged by subsequent work showing prior ED activity's (EDA) highly significant association with ED recovery time. However, prior EDA's association with ED recovery does not rule out the possibility that the stimulus meaning may also affect recovery. In the present study a within-subjects design (N = 10) was used to evaluate effects of stimulus significance on skin conductance response (SCR) amplitude and recovery time (rec t/2) while prior EDA was held constant. Amplitude was greater and rec t/2 longer (slower) when the stimulus significance increased, and the effect on recovery did not depend entirely on amplitude. Prior EDA also affected amplitude and recovery but stimulus meaning had an additional effect. These findings contradict the notion of the EDR as a unitary phenomenon, and imply that both peripheral and central mechanisms are involved in determining response amplitude and recovery. Stimulus meaning may affect recovery to an even greater degree than it affects amplitude.