Bilateral electrodermal activity: reliability, laterality and individual differences.
A first aim of the present study was to estimate the short- and long-term stability of individual response patterns in bilateral electrodermal activity (EDA). A second aim was to examine the relationship of individual brain laterality to both peak amplitude and peak time based electrodermal asymmetry. Additionally, subjects were presented with verbal and spatial tasks to estimate the balance of left/right asymmetry in cerebral activation at time of testing. Finally, the influence of smoking, coffee consumption and subjective circadian phase (morningness/eveningness, subjects' rise time) on bilateral asymmetry and EDA lability was examined. Results indicated moderate to high short-term reliabilities of EDA laterality coefficients, but insufficient long-term stability. Handedness and conjugate lateral eye movements (CLEMs) were not related to asymmetry of EDA, but a significant interaction between CLEM tendency and smoking/nonsmoking on laterality of both EDA parameters was observed. Amount of coffee consumption was also significantly related to electrodermal asymmetry. Analysis of performance data demonstrated that intraindividual shifts of EDA laterality from one recording session to a following one were associated with corresponding shifts in accuracy of verbal/spatial performance. Degree of subjects' electrodermal lability differentiated significantly between speed and accuracy of performance in both verbal and spatial tasks, and was substantially related to subjects' rise time.