Influence of Relative Humidity on Electrodermal Levels and Responses

Electrodermal activity (EDA) is a widely used measure in psychophysiological research, and its use in wearable devices has grown in recent times. It is recommended to have proper conditions for EDA measurement, and skin hydration is one factor that has a significant influence. It is, however, not known to what extent the ambient humidity influences the recording. This study explored the influence of relative humidity (RH) on EDA levels, and also the responses using a new technique for simultaneous recording of all measures of EDA: skin conductance (SC), skin susceptance (SS), and skin potential (SP) at the same skin site.

A total of 10 healthy subjects were exposed to environments of low and high RH while EDA measures were recorded, including cognitive, visual and breathing stimuli for evoking electrodermal responses of different origin. EDA levels and responses were compared between the two humidity levels for all stimuli and all EDA measures.

It was found that EDA levels, in particular for SC and SS, were significantly increased during high humidity exposure, but that the change in EDA responses (SC, SS, and SP) was not statistically significant (p > 0.05, paired t test).

This suggests that ambient humidity influences the recording of EDA levels and is important to consider when these parameters are used, but is not important in the recording or analysis of EDA responses.