[Are psychophysiologic changes in the "public speaking" paradigm an expression of emotional stress?].

Public Speaking is often used to induce anxiety. The emotional stress elicited by the anticipation of delivering a public speech, however, is usually confounded with the mental stress of speech preparation. In order to separate the effects of the emotional from those of the mental stress factor, only half of the subjects were informed about the topic of the speech at the beginning of the anticipation period, whereas the other half were told about the topic at a later time. In a pilot study, the effects of this variation were tested under a condition in which the subjects were told that the speech would be videotaped as an anxiety-provoking and under an emotionally neutral control condition. The main experiment involved an additional condition with a simulated audience designed to intensify the impact of the emotional stress component ("strong anxiety"). Self-reports on present state and cardio-vascular and electrodermal responses were measured in n = 12 subjects in both studies. Knowledge of the speech topic did not affect the subjective anxiety-inducing effects of public speaking. Physiologically arousing effects, however, could be shown without knowledge of the topic only in some variables and only under the "strong anxiety"-provoking condition. In studying public speaking anxiety, confounding with the mental stress of speech preparation should therefore be avoided and a more differentiated interpretation of the physiological effects should be made.