Anxiety and autonomic flexibility: a cardiovascular approach1Portions of this paper were presented in J.F. Thayer (Chair), New Approaches to Cardiovascular Reactivity Symposium conducted at the 33rd Annual Meeting of the Society for Psychophysiological Research, October 1993, Rottach-Egern, Germany. This study was conducted in partial fulfillment of the requirements of the doctoral dissertation of the first author.1