The author contends that the activation theory of emotions is the most adequate to date for conceptualizing the intensitive dimension of emotion, and that electrical skin conductance is a good measure of the extent of activation present. For other dimensions of emotion, however, he feels that other measurement approaches are necessary and discusses facial expressions as one of these. Evidence is presented from facial expression studies which indicates that the whole range of such expressions can be described in terms of a circular surface with pleasantness-unpleasantness and attention-rejection as axes, with level of activation as a possible third dimension. It is concluded that facial expressions and body changes supplement each other in giving us the dimensions along which emotions may vary.(PsycINFO Database Record (c) 2016 APA, all rights reserved)