A method for computing a quantitative metric indicative of pain experienced by a subject using an electrophysiological signal detection system is provided. Electrophysiological data are acquired from a subject with the electrophysiological signal detection system. Modulations in the acquired electrophysiological data that are associated with pain experienced by the subject during the acquisition of the electrophysiological data are identified. A quantitative metric indicative of the pain experienced by the subject is computed by processing the identified modulations in the acquired electrophysiological data.