Who they are
Stephen W. Porges is an American neuroscientist and psychophysiologist who developed Polyvagal Theory (PVT) — a model of the autonomic nervous system that proposes three hierarchically organised subsystems corresponding to evolutionary stages. He is a Distinguished University Scientist at Indiana University’s Kinsey Institute and the creator of the Safe and Sound Protocol (SSP), a commercial auditory intervention derived from PVT. See Polyvagal theory and the Safe and Sound Protocol for the full topic overview.
Porges is included here because PVT has become enormously influential in therapeutic communities working with autistic people. Whether that influence is warranted is actively contested.
Key contributions
Polyvagal Theory
PVT proposes that the vagus nerve has three functionally distinct branches corresponding to evolutionary stages: the dorsal vagal complex (immobilisation/shutdown), the sympathetic nervous system (fight-flight), and the ventral vagal complex (social engagement/safety). The theory claims that the ventral vagal state underpins social connection, emotional regulation, and the ability to feel safe, and that autism involves under-functioning of this system.
Clinicians find PVT popular because it offers a physiological narrative for emotional states: “in dorsal” (shut down), “in sympathetic” (fight-flight), or “in ventral” (safe and social). This language is widely used in therapy.
The Safe and Sound Protocol
SSP uses algorithmically filtered music — emphasising frequencies in the human voice range — to stimulate the ventral vagal system. Some evidence shows reduction in auditory hypersensitivity following SSP, though benefits for social functioning are minimal.
Critical assessment
This is where honesty requires directness. Polyvagal Theory has attracted sustained, serious scientific criticism:
The anatomical and evolutionary claims at PVT’s core are disputed. The structures Porges identifies as evolutionarily recent and uniquely mammalian are found in ancient vertebrates. A 2023 paper in Biological Psychology described “fundamental challenges and likely refutations” of PVT’s five basic premises. Critics argue the theory may be unfalsifiable.
Respiratory sinus arrhythmia (RSA), the primary measurement used to index vagal tone in PVT research, shows dissociation from vagally mediated heart rate changes, weakening the measurement foundation.
PVT frames autism as a social-engagement deficit (ventral vagal underfunctioning), which pathologises autistic neurology and conflicts with neurodiversity-affirming approaches. It implies autistic social differences result from a nervous system “stuck” in threat mode rather than reflecting a different way of processing social information. See Polyvagal theory and the Safe and Sound Protocol for the full critique.
Porges and colleagues published a 2024 response countering that critics misrepresent the theory. The debate remains unresolved.
SSP is a proprietary product with certification and licensing fees. Porges has a financial interest in PVT’s credibility.
Selected works
- Porges, S.W. (2011). The Polyvagal Theory: Neurophysiological Foundations of Emotions, Attachment, Communication, and Self-Regulation. New York: Norton. — The comprehensive statement.
- Porges, S.W. (2001). “The polyvagal theory: Phylogenetic substrates of a social nervous system.” International Journal of Psychophysiology, 42(2), 123–146. — The key theoretical paper.
- Porges, S.W. et al. (2014). “Reducing auditory hypersensitivities in autistic spectrum disorder: Preliminary findings evaluating the listening project protocol.” Frontiers in Pediatrics, 2, 80.
Last reviewed
2026-04-15