Resting RSA is associated with natural and self-regulated responses to negative emotional stimuli.

Resting respiratory sinus arrhythmia (RSA) was assessed among 111 adult participants. These individuals were then asked to watch a positive or negative affective film in either a natural manner or while exaggerating their facial response. Facial reactions to the film were video-recorded and subsequently rated in terms of facial affect. Participants also self-reported the valence of their emotional experience. Results from regression analyses revealed that persons with low resting RSA behaviorally evidenced a more negative facial response to the negative film under natural-watch conditions. Low RSA individuals were also less able to modulate (i.e., amplify) their facial response to the negative film. In terms of self-report measures, persons in the exaggerate condition reported more positive affect to the positive film than did those in the natural-watch condition. Results suggest that cardiac vagal control is inversely associated with negative facial expression but positively associated with facial regulation ability to negative stimuli.