The concept of psychophysiological arousal as a component of emotional behavior has a long history, but has not attracted the research attention paid to valence in the burgeoning field of affective neuroscience. The potency of emotional stimuli is often poorly balanced in studies designed to assess appetitive and aversive stimulus processing, and thus I applaud Picard and colleagues’ choice to highlight the arousal dimension of emotional behavior. Any attempt to understand the nature of human emotion must carefully balance the evocative (...) impact of appetitive and aversive processes. By focusing on the contribution of arousal to emotional processing, Picard advances this goal. In this comment I suggest methodological and conceptual refinements that may help to strengthen the multiple arousal theory perspective. (shrink)