Evidence for differentiation of arousal and activation in normal adults.

"Arousal" at a particular time has been defined as the energetic state at that moment, reflected in electrodermal activity and measured by skin conductance level. In contrast, task related "activation" has been defined as the change in arousal from a resting baseline to the task situation. The present study, replicating some aspects of a previous investigation of these ideas in children, aimed to further explore whether the separation of "arousal" and "activation" was useful in describing state effects on the phasic Orienting Response (OR) and behavioral performance. A continuous performance task (CPT) was used with normal adults. It was found that the magnitude of the mean phasic OR to targets was dependent on arousal, but not on task-related activation. A performance measure (reaction time) improved with increasing activation, but not with arousal. These findings support our previous suggestions concerning the value of conceptualizing arousal and activation as separable aspects of the energetics of physiological and behavioral function.