ABSTRACTThe study was designed to examine the relationship between electrodermal frequency (EF) and skin conductance level (SCL) in a paradigm that has previously demonstrated that these measures can operate independently. Electrodermal activity was recorded during 3 10‐min periods. All subjects rested during the first and last periods. Half of the subjects rested during the second period, and half were in a shock‐threat condition. Between the second and third periods a fresh electrode set was applied, and the subjects either inflated a balloon, operated a pursuit rotor, or were interviewed. Both measures were low for the rest periods and high during the shock‐threat condition except during the last rest period when SC was unexpectedly high, thus replicating previous research. However, application of new electrodes in the last period demonstrated that this high SCL was due to a time dependent effect, probably hydration, and was not due to the differential effects of stress and cognitive activity on the two electrodermal mea