A Guide to Cleaner Electrodermal Activity Measurements

Abstract

Valid electrodermal measurements ensure the integrity of client assessment and biofeedback training. Accurate measurements require understanding of the signal and potential artifacts (sources of contamination) and developing “bulletproof procedures.” Peper, Shaffer, and Lin have recommended the following guidelines for ensuring accurate psychophysiological monitoring: (a) understand the physiological mechanisms that generate the signal, (b) always record and inspect the raw signal because this will allow you to identify artifact, (c) question whether displayed values make sense (e.g., skin conductance levels that rapidly fluctuate, exceed 40 μS/cm 2 , or fall below 1 μS/cm 2 should be suspect in a client who is sitting quietly), (d) recognize the appearance of common artifacts and how they alter derived measurements, and (e) intentionally create artifacts so that you can better recognize them (e.g., rhythmically move the fingers attached to a skin sensor, loosening or tightening the sensors if they are attached with the Velcro® finger straps, and review both the raw signal and calculated skin conductance values). This article reviews the anatomy and physiology, measurement procedures, sources of common artifacts and their control, tracking test for recording electrodermal activity, and common response patterns.