Differential Dermal Potential: A New Paradigm for Measuring Cognitive Load.

Electrodermal activity of skin varies with cognitive load (CL). Galvanic Skin Response (GSR) is mostly used for measuring CL. Here, we studied the effect of CL on endosomatic differential dermal potential (DDP). DDP signals were recorded while executing mental addition tasks of two difficulty levels. A two-level classification approach was adopted where first level, discriminate rest state from overload condition and the second level discriminate between low and high CL. Significant variation in DDP signal was observed for various CL levels. We achieved a classification accuracy of 80.01% (f-score 0.83) for Rest vs Load condition and 72.33% (f-score 0.71) for Low vs High load classification which are better than that obtained using GSR. Literature suggests that it is possible to record skin potential and GSR signals simultaneously from a particular site. However, we found that as CL increases, the presence of GSR reduces the discriminating ability of DDP, thereby reducing the classification accuracy of both Rest vs Load and Low vs High conditions. The proposed approach, along with the recommended set of features, can be used to assess CL of an individual while doing a task.