1. A system for quantifying at least one sympathetic response on the face, the system comprising: a thermal imager adapted to measure signals from at least one facial region selected from the group consisting of supraorbital, periorbital, and maxillary regions; wherein the measured signal is at least one selected from the group consisting of blood flow in the facial/ophthalmic arteriovenous complex, blood flow in the supraorbital area, perspiration in the supraorbital area, and perspiration in the maxillary area; and at least one ground-truth probe synchronized with the thermal imager via an electronic circuit.