Electrodermal activity as an index of motion sickness.

Sweating in the absence of thermal stimulation is one of the cardinal symptoms of motion sickness. But since sweating is closely related to electrodermal activity this may be a potentially useful index of the intensity of motion sickness. In order to evaluate this possibility, the correlations between electrodermal activity and a range of signs and symptoms of motion sickness were examined in four experiments, in which a total of 170 subjects were exposed to a cross-coupled force environment. Although increases in skin conductance did not correlate with specific single indices of motion sickness, correlations with a questionnaire based on several signs and symptoms varied from 0.89 (p less than 0.001) to 0.11 (N.S.). It is concluded that skin conductance potentially offers a valid and very precise measure of motion sickness, but that it is sensitive to extraneous factors only some of which are currently understood.