Use a CBLCFMA to monitor and record the actual current delivered to the participant at ALL times.
Always make sure to place the electrodes on the participant at least 10 minutes before starting any electrical stimulation.
A large enough change in current delivered to the participant will alter the subjective perception of the stimulation. Thus, an unpleasant shock may become painful if more current starts being delivered or become ineffectual if less current is being delivered than during threshold identification. Changes in the levels of delivered current are due to changes in impedance. Changes in impedance could be due to a number of factors: gel saturating the skin over time; gel drying up—over longer period of times; hydration level of participant; sweating; decoupling of electrodes and skin due to motion artifacts; etc.