In February 2026, thirty-nine researchers in vagal physiology and vertebrate evolution published a paper in Clinical Neuropsychiatry titled "Why the Polyvagal Theory Is Untenable." In the same issue, Stephen Porges, who developed the theory, published a rebuttal. Polyvagal theory has shaped how a generation of clinicians, parent coaches, and educators talk about the nervous system, including in the PDA world, and including, in places, us. So this deserves a careful look: what the critics said, what Porges said back, and what it means for how we understand Pervasive Drive for Autonomy (PDA, formerly called Pathological Demand Avoidance).
The Grossman paper is notable less for its conclusion than for who signed it. Many of the co-authors are physiologists whose own work has been cited in polyvagal writing as supporting the theory. Their argument targets the physiology specifically. They contend that respiratory sinus arrhythmia, the heart-rate measure polyvagal theory leans on, is not a direct or reliable index of vagal output to the heart. They contend that the sharp functional split between the "ventral" and "dorsal" vagal pathways, the anatomical basis of the well-known autonomic "ladder," is not supported by the evidence, and that the concept of "dorsal vagal shutdown" in humans lacks empirical grounding. They dispute the evolutionary story, presenting evidence that reptiles, birds, and fish have the fast myelinated vagal fibers the theory said were uniquely mammalian, and that non-mammalian animals show rich social behavior. Their conclusion is that the theory's physiological premises are not defensible on current neurophysiological and evolutionary evidence.
Porges' response, "When a Critique Becomes Untenable," does not primarily contest the individual physiological findings. His central claim is that the critics evaluated a simplified reconstruction of the theory rather than the theory as it is articulated in the peer-reviewed literature, and that this constitutes a category error. He frames polyvagal theory as a holistic model of autonomic state regulation that cannot be refuted by disputing anatomical claims one at a time, and he argues several of the criticisms were raised and addressed years ago. Critics of his response have replied that a theory which cannot be tested piece by piece risks becoming unfalsifiable. Supporters have replied that the clinical practices associated with the theory, co-regulation, attention to safety, somatic awareness, work regardless of the mechanism debate.
We are not vagal physiologists, and we are not going to pretend to adjudicate a dispute among people who have spent their careers on the vagus nerve. What we can do is be clear about what this debate does and does not touch for PDA.
Both sides agree on something important: the psychological concepts, felt safety, co-regulation, the observation that a stressed nervous system narrows what a person can do, predate polyvagal theory by decades and do not depend on it. The dispute is about the physiological story underneath them, not about whether they are real.
The core claim RELATE makes about PDA does not rest on polyvagal physiology, and never did. The claim is this: a demand is perceived as a threat to autonomy, that perception triggers a threat response, and under threat, compliance becomes neurologically inaccessible. Can't, not won't. The evidence for that claim comes from three converging lines, none of them polyvagal. Subcortical threat detection, the fast, pre-conscious threat appraisal that the amygdala and related circuitry perform, is mainstream affective neuroscience. Intolerance of uncertainty, shown by Stuart and colleagues in 2020 to predict PDA traits more strongly than anxiety alone, is a well-characterized construct with its own research base. And the treatment of autonomy loss as a survival-level threat draws on attachment and self-determination research that long predates Porges.
The same is true of the framework's working tools. The window of tolerance comes from Siegel, not polyvagal theory. Co-regulation and felt safety come from Bowlby and the attachment tradition. Fight, flight, and freeze are stress physiology that no one in this debate disputes. If every polyvagal-specific claim were removed from the literature tomorrow, the RELATE mechanism and its pillars would stand exactly as they are.
Here is where we owe transparency. Like most of the field, we have used polyvagal vocabulary in places. Our site has listed polyvagal theory among the research traditions RELATE draws on, alongside attachment science, intolerance of uncertainty, and affective neuroscience. We have used the word "neuroception," a term Porges coined, to describe the nervous system's capacity to read other nervous systems below conscious awareness. We used that vocabulary because it was the field's shared language, and because the phenomena it pointed to are real.
We are not deleting or rewriting those posts. We think that would be the wrong instinct. Scrubbing a site to look like you were never influenced by a contested idea is a kind of dishonesty, and it teaches readers nothing. Instead we are doing what journals do: leaving the originals in place, adding a dated note where the language is affected, and publishing this update alongside them. Going forward, our new writing describes the underlying phenomena in terms that do not depend on the disputed physiology: threat detection rather than neuroception, nervous system state rather than vagal state, and the converging evidence base we actually rest on rather than polyvagal theory as a named source.
RELATE describes itself as evidence-informed rather than evidence-based, and we have always meant that precisely. There are no randomized controlled trials of RELATE, and we say so plainly. What there is, is a mechanism grounded in converging research, applied clinically, and revised when the research moves. This debate is exactly the kind of movement that should prompt revision, and this post is us revising in public.
Our commitments are simple. We do not delete or silently edit past writing; we annotate it and publish updates beside it. We follow the evidence where it goes, including when it is inconvenient. We present live scientific disputes as disputes, not as settled in whichever direction we prefer. And we distinguish, always, between the phenomena we observe in PDA, which are robust, and the physiological explanations offered for them, which are the proper subject of ongoing science. A framework that cannot survive its explanatory vocabulary being updated was never a framework. It was a brand.
We will keep watching this literature and update again when it warrants. The critics' paper is here and Porges' response is here; we encourage anyone who works with PDA to read both. For the mechanism as we describe it, see What Is PDA? and the RELATE framework.