LumEDA: image luminance based contactless correlates of electrodermal responses

<i>Objective</i>. Electrodermal activity (EDA) is a marker of psychophysiological arousal and is usually a measure of the skin conductance which is associated with sweat gland activity. Recent studies have shown that it is possible to estimate the EDA using contactless video based methods.<i>Approach</i>. Sensor EDA signals (SenEDA) and videos of the the palm were recorded simultaneously from over 30 participants under various stimuli (audio, video, cognitive and physiological). The luminance information from the video data was used to track sweat gland activity on the skin surface and extract the contactless signal luminance based EDA (LumEDA).<i>Main results</i>. Comparison of the SenEDA and LumEDA signals showed a high positive correlation between the two as expected.<i>Significance</i>. Under suitable illumination, simple spatial filters can be used to track sweat gland activity which can then be used to estimate signals analogous to the EDA. Such video based methods also facilitate spatio-temporal analysis of EDA correlates over larger areas of the body.