Bernstein et al. (1985) presented the results of an extensive study of the effects of stimulus significance upon electrodermal and heart rate responses. This report examines some of these data from the perspective of preliminary process theory (Barry, 1984b). The categorisation of significance manipulations into prestimulus vigilance and poststimulus signal value outcomes is supported by differential responding in the electrodermal and cardiac measures, as predicted by preliminary process theory. © 1988.