Orienting in a defensive world: Mammalian modifications of our evolutionary heritage. A Polyvagal Theory


  • This paper is based on the Presidential Address to the Society for Psychophysiological Research, Atlanta, GA, October 8, 1994.

  • The Presidential Address and the published manuscript are dedicated to the memory of my close friend and collaborator, Robert E. Bohrer.

  • The theory described in this paper evolved from three decades of research and interactions with colleagues and students. I am indebted to six individuals who have provided scientific and intellectual guidance as the Polyvagal Theory evolved. Robert E. Bohrer tutored me in time series statistics. Sue Carter who, as my emotional and intellectual partner, supported and contributed to my scientific curiosity throughout my professional career. Stanley I. Greenspan stimulated my interest in affective processes and psychopathology. Ajit Maiti mentored me in the neurophysiology and embryology of the brainstem. David C. Raskin introduced me to psychophysiology. Evgeny Sokolov provided a model as a mentor and stimulated me to generate an integrative theory. In addition, I have been fortunate to have outstanding associates, collaborators, and students, including Olga Bazhenova, Evan Byrne, Michael Cheung, Aaron Chun, Georgia DeGangi, Janet DiPietro, Yoel Denchin, Jane Doussard-Roosevelt, Nathan Fox, Phil Goddard, Sandy Larson, Susan Linnemeyer, Phil McCabe, Oxana Plonskaia, Lourdes Portales, Shawn Reed, Todd Riniolo, Pat Suess, and Brandon Yongue, who have contributed to the research and development of the Polyvagal Theory. An additional thanks to Jane Doussard-Roosevelt who provided the intellectual and emotional ballast in my laboratory during my presidency and who contributed to the manuscript and talk by editing earlier versions and generating the graphics. Thanks to Gary Berntson and John Cacioppo for their valuable comments on an earlier version of this paper. The preparation of this manuscript was supported in part by grant HD 22628 from the National Institute of Child Health and Human Development and by grant MCJ 240622 from the Maternal and Child Health Bureau.

Address reprint requests to Stephen W. Porges, Department of Human Development, University of Maryland, College Park, MD 20742, USA. E-mail: porges@umdd.umd.edu.


The vagus, the 10th cranial nerve, contains pathways that contribute to the regulation of the internal viscera, including the heart. Vagal efferent fibers do not originate in a common brainstem structure. The Polyvagal Theory is introduced to explain the different functions of the two primary medullary source nuclei of the vagus: the nucleus ambiguus (NA) and the dorsal motor nucleus (DMNX). Although vagal pathways from both nuclei terminate on the sinoatrial node, it is argued that the fibers originating in NA are uniquely responsible for respiratory sinus arrhythmia (RSA). Divergent shifts in RSA and heart rate are explained by independent actions of DMNX and NA. The theory emphasizes a phylogenetic perspective and speculates that mammalian, but not reptilian, brainstem organization is characterized by a ventral vagal complex (including NA) related to processes associated with attention, motion, emotion, and communication. Various clinical disorders, such as sudden infant death syndrome and asthma, may be related to the competition between DMNX and NA.