Analytic measures for quantification of arousal from spontaneous skin conductance fluctuations

Abstract

Autonomic arousal is often indexed by spontaneous fluctuations in skin conductance. Here, we derive a simple measure of sympathetic arousal, using a convolution model of how sudomotor bursting causes fluctuations in skin conductivity. Under this model, the time-integral of measured conductance is proportional to the frequency and amplitude of sudomotor bursts. We demonstrate the validity of this measure in relation to finite impulse response models, and show that it is a better predictor of autonomic arousal, relative to conventional measures.

Fig. 1

A: The response function estimated across participants with an uninformed finite impulse response model that deconvolves potentially overlapping responses. The time at 0 s corresponds to peak time as detected by semi-automated conventional analysis. B–D: Correlation of the AUC with conventional SF measures, derived from semi-automated conventional analysis. All correlations were significant (p < 0.0001). E: AUC (black) and number × mean response amplitude (multiplied with the scaling constant c) predict autonomic arousal in a public speaking anticipation experiment, but AUC is a better predictor (see text for statistical inference). BL1 and BL2: baseline measurements. R1: measurement after announcement of a public speech. R2: measurement after announcement of the speech topic. Values are shown as mean and standard error.