Spend any time around somatic therapy and you’ll meet the vocabulary: ventral vagal, dorsal vagal, co-regulation, neuroception. It comes from Stephen Porges’s polyvagal theory, and it has been enormously influential on how therapists talk. It’s also genuinely contested, and you deserve both halves of that.
What it proposes
That the autonomic nervous system has three states rather than two, arranged in an evolutionary hierarchy. A ventral vagal state of social engagement, where you can connect, meet someone’s eyes and be soothed. A sympathetic state of mobilisation, which is fight or flight. And a dorsal vagal state of shutdown and collapse, used when mobilising has failed.
Alongside that, neuroception: the idea that your system is constantly appraising safety below awareness, and that this appraisal, not your reasoning, decides which state you’re in.
Why therapists took to it
Because it named something clinicians already saw and had no clean language for. It explains why someone can be flooded one week and flat the next, why shutdown isn’t calm, and why safety and relationship might be prerequisites for the work rather than pleasantries around it.
Co-regulation — that nervous systems settle near a settled other — turned out to be a useful way of describing what a therapist is doing in the room. That has value regardless of the underlying anatomy.
The criticism, stated fairly
Several comparative physiologists have challenged the evolutionary claims at the theory’s core, particularly the phylogenetic story about vagal pathways in reptiles and mammals. Paul Grossman and others have published detailed critiques arguing that key premises aren’t supported and that some specific physiological predictions don’t hold up.
This is a real scientific dispute between qualified people, not a fringe objection, and it hasn’t been resolved in Porges’s favour.
What to do with that
Hold the clinical vocabulary loosely and the anatomy more loosely still. That people move between mobilised, shut-down and settled states is observable and useful no matter which nerve turns out to be responsible. That safety and relationship matter to therapy is well-supported by evidence with nothing to do with polyvagal theory.
What should make you cautious is a practitioner who treats the theory as settled fact, explains your symptoms as your dorsal vagal, or sells you a protocol for toning your vagus nerve. Confident mechanism-talk built on a contested model usually means somebody read the popularisation and not the argument.
Sources
Both sides linked deliberately. This page argues the theory is contested, not that it has been disproved, and you should be able to read the argument yourself.
- Grossman, P. (2023). Fundamental challenges and likely refutations of the five basic premises of the polyvagal theory. Biological Psychology. — The detailed critique of the theory’s physiological and evolutionary premises.
- Polyvagal Institute — critical discussion — Responses defending the theory, collected by its own institute. The dispute is live and has not been settled either way.