Significant, Not Sacred: A Clinical Educator's Response to Grossman et al.

Significant, Not Sacred: A Clinical Educator's Response to Grossman et al. (2026) on the Critique of Polyvagal Theory

Rebecca Kase, LCSW

Founder, Trauma Therapist Institute

Author, The Polyvagal Solution; Polyvagal-Informed EMDR; The Applied Polyvagal Flip Chart

February 2026

In February 2026, Paul Grossman and 38 co-signatories published an article in Clinical Neuropsychiatry declaring Polyvagal Theory (PVT) "untenable," concluding that its core premises are "not defensible based on existing neurophysiological and evolutionary evidence" (Grossman et al., 2026). This is not Grossman’s first refutation of Polyvagal Theory (Grossman & Taylor, 2007) (Grossman 2016, 2023). In the same issue, Stephen Porges published a detailed scholarly response (Porges, 2026). This is neither Porges’s first response to Grossman’s critiques (Porges, 2007, 2021, 2025a) This recent exchange has generated significant attention across the trauma therapy community, as did the criticism in 2016, and clinicians are understandably asking what this means for their practice.

I write this response as a licensed clinical social worker, an EMDR consultant and trainer, and the founder of the Trauma Therapist Institute, where we have provided trauma-focused continuing education to over 20,000 clinicians since 2017. I am the author of Polyvagal-Informed EMDR: A Neuro-Informed Approach to Healing (Kase, 2023), The Polyvagal Solution: Vagus Nerve-Calming Practices to Soothe Stress, Ease Emotional Overwhelm, and Build Resilience (Kase, 2025), and The Applied Polyvagal Flip Chart (Kase, 2023). My work sits at the intersection of neuroscience and clinical translation. I do not claim expertise in comparative neuroanatomy. I do claim extensive experience in applying polyvagal-informed frameworks with clinicians who are navigating some of the most complex presentations our field encounters, and in translating autonomic neuroscience into usable clinical tools.

That translational vantage point is relevant to this conversation because the Grossman critique evaluates PVT exclusively at the level of neurophysiological mechanisms. It does not address the clinical, educational, or systems-level contributions that PVT has made to the treatment of trauma. Both levels of analysis matter. A complete evaluation requires both.

Acknowledging Legitimate Scientific Questions

Scientific models evolve. That is how serious disciplines grow. Some of the questions raised by Grossman and colleagues are reasonable areas of inquiry. Debate about the specificity of respiratory sinus arrhythmia (RSA) as an index of ventral vagal tone, the precise role of the dorsal motor nucleus of the vagus (DMNX) in cardiac regulation, the functional distinction between vagal nuclei, and the evolutionary timeline of vagal organization are legitimate domains of neuroscientific investigation. No serious scientist claims any model is final, and Porges himself has consistently framed PVT as a working model open to revision and refinement (Porges, 2022, 2023, 2025b).

Engaging these questions strengthens a field. It does not invalidate it. The relevant question is not whether PVT is flawless. The question is whether PVT has meaningfully advanced understanding, clinical practice, and the systems that serve people who have experienced trauma. The answer, supported by three decades of clinical and translational evidence, is yes.

What Is Actually Being Critiqued

To understand the current debate, it is important to distinguish between what the Grossman critique does and does not address.

At its core, Polyvagal Theory proposes that autonomic state functions as an organizing platform that shapes perception, emotion, behavior, and relational capacity. This central clinical insight was not empirically disproven in the critiques offered by Grossman and colleagues. Instead, their 2026 paper focuses primarily on the biological testability of certain elements of the theory. Specifically, the authors question aspects of PVT’s descriptions of neuroanatomical pathways, methods for measuring vagal function, evolutionary interpretations, and claims about mammalian sociality, with critiques of reptilian sociality. On this basis, they argue that the model rests on biologically unsupported assumptions. The article represents the most comprehensive scientific critique of Polyvagal Theory to date and its criticisms are relevant and deserve serious consideration.

In his published response, Stephen Porges argues that the critique engages a “reconstructed proxy” of Polyvagal Theory rather than the theory as it has been articulated in the peer-reviewed literature. He contends that the authors evaluate an oversimplified or partially misrepresented version of the model and, as a result, draw conclusions that are misaligned with its actual premises. In this sense, the disagreement is not only about data, but also about how the theory itself is being defined and interpreted.

Debate of this kind is not a problem. It is a hallmark of a healthy, evolving scientific field. From the beginning, Porges has emphasized that Polyvagal Theory is not doctrine. It is a working model and an invitation to inquiry, refinement, and continued research. These discussions reflect what responsible science is meant to do: test assumptions, challenge interpretations, and deepen understanding.

What is notably absent from the Grossman critique, however, is a substantive alternative framework. While the authors identify perceived limitations in Polyvagal Theory, they do not offer a revised model or coherent replacement to guide clinical understanding and practice.

Grossman and colleagues note that many concepts associated with PVT “predate PVT by many decades.” While it is true that elements resembling polyvagal-informed thinking can be found across earlier theories and modalities, these ideas were rarely integrated into a comprehensive and accessible framework for clinicians. As a licensed therapist with two decades of experience, I am not aware of any widely adopted therapeutic model prior to PVT that offered a systematic way to conceptualize autonomic state alongside the roles of social engagement and physiological safety.

The authors also assert that “abundant research and theoretical formulations exist” addressing autonomic afferent and efferent regulation. Yet in practice, much of this research has remained fragmented, siloed, and difficult for clinicians to translate into everyday therapeutic work. Existing frameworks, while valuable in specific scientific contexts, have often lacked the coherence, robustness, and clinical usability required to meaningfully guide front-line helping professionals.

In this respect, Polyvagal Theory has filled a critical gap. It has helped bridge complex physiological research with real-world clinical application in a way few other models have achieved.

As these debates move into social media and popular psychology spaces, they are frequently flattened into all-or-nothing narratives. If one component of the theory is questioned, the entire model is portrayed as “debunked,” obsolete, or unworthy of serious attention. Headlines such as “R.I.P. Polyvagal Theory”(Tang, 2021) exemplifies this tendency toward oversimplification. Such framing is misleading and reflects click-driven media dynamics more than thoughtful scientific engagement.

What we are witnessing is not a battle between good science and bad science. It is a tension between two legitimate scientific traditions.

One approach prioritizes microscopic precision: clearly mapped anatomy, tightly controlled measurements, and narrowly defined mechanisms. Its guiding question is, “Can we demonstrate this pathway with exact biological specificity?” I deeply respect that approach as it is needed and necessary for scientific rigor, integrity, and accuracy.

The other tradition prioritizes integration and application: how complex physiological systems function in real human beings, across relationships, environments, and developmental contexts. Its guiding question is, “Does this model help us understand and respond to lived human experience?” Polyvagal Theory did not resonate globally because of its anatomical diagrams. It resonated because it reframed health and pathology through the lens of autonomic state, offering clinicians and systems a coherent way to understand how physiology shapes behavior, resilience, and disease.

Both approaches matter. Both are necessary. And neither invalidates the other.

The Paradigm Shift That PVT Enabled

No theoretical model in mental health is without limitations. Every widely used framework contains unresolved questions and areas of ongoing debate. Most do not clearly articulate their mechanisms of action at the level of neurophysiology. Many interventions are adopted long before their biological underpinnings are fully understood.

Polyvagal Theory is not a therapy, nor does it prescribe a specific treatment protocol. What it offers is something many helping professionals have long needed: a working model for understanding the neurophysiology underlying symptoms, diagnoses, and relational patterns. It provides a lens through which clinicians can track autonomic state, interpret behavior through the language of regulation rather than pathology, and more thoughtfully align interventions with physiological capacity.

Stephen Porges has grounded this framework in detailed discussions of neurophysiological mechanisms through his research, publications, and teaching. At the same time, Deb Dana has translated these concepts into accessible language and practical tools for clinical and educational settings. Together, their work has created a rare bridge between theory and practice in mental health.

That bridge is not trivial. It has meaningfully shaped clinical training, systems design, and professional discourse. And like all responsible scientific models, Polyvagal Theory can continue to evolve without losing the impact it has already made.

Before Polyvagal Theory entered the clinical landscape, most therapeutic and health models were symptom-focused, cognitively dominant, and largely disconnected from autonomic mechanisms. Clinicians received minimal training in autonomic physiology, state-dependent functioning, or neurobiological safety. The prevailing assumption was that cognitive insight could, on its own, resolve trauma. For many survivors of complex and developmental trauma, this was simply not the case.

PVT shifted the field in ways that transcend neuroanatomical diagrams. It moved clinical thinking from symptom to mechanism, offering clinicians a way to understand why certain symptom constellations cluster together and why they resist purely cognitive intervention. It moved clinical attention from story to state, providing a framework for recognizing that a client's physiological state constrains access to cognition, emotion, and relational capacity. When a nervous system is in defensive dominance, higher-order cortical processes are functionally constrained.

PVT also moved the field from pathology to adaptation. Porges (2022, 2025a) reconceptualized psychological and behavioral symptoms as adaptive expressions of autonomic state rather than evidence of cognitive or emotional failure. This reframe, from judgment to curiosity, from "what is wrong with you" to "what happened to you and what is your nervous system doing about it," has been foundational to trauma-informed care across disciplines.

The Social Engagement System and the Biology of Relationship

Therapy has always emphasized the importance of the therapeutic relationship. Decades of psychotherapy research confirm that the quality of the therapeutic alliance is among the strongest predictors of outcome. But for most of that history, we could describe that relationship matters without fully articulating why it matters at the level of biology.

PVT offered a mechanism. The social engagement system, involving the coordination of neural circuitry between the heart, the throat, and the head, provides a biologically grounded explanation for co-regulation. The vagus nerve works in conjunction with cranial nerves V, VII, IX, and XI to integrate sensory and motor feedback from the muscles of the jaw, face, tongue, and neck, coordinating social communication through facial expression, voice prosody, and listening (Porges, 2022). This reframed the therapeutic alliance from a relational "soft skill" to a biological necessity. As Cozolino (2014) describes, this interpersonal exchange crosses a "social synapse" that enables one nervous system to sense and respond to another.

PVT also provided a coherent explanatory model for what clinicians observe daily: that the vagus nerve can mediate both calming "rest and digest" responses and the vasovagal shutdown seen in freeze, collapse, and dissociative presentations. This is the paradox of the parasympathetic nervous system that Schwartz (2026) describes. It is commonly understood that post-traumatic stress is associated with fight/flight reactivity driven by sympathetic activation. But a subset of individuals with the dissociative subtype of PTSD present with predominant symptoms of depersonalization, derealization, fatigue, and withdrawal from social engagement (Lanius et al., 2012; Kozlowska et al., 2015). PVT offers one coherent model for understanding these divergent presentations.

Grossman and colleagues have not proposed an alternative framework to replace Polyvagal Theory, nor have they offered a revision of its core hypotheses grounded in their cited research. Instead, they argue that certain tenets of PVT are incorrect, tenets which Porges maintains have been mischaracterized or misinterpreted, and from that conclusion suggest the entire model is untenable. 

That absence matters. A critique that declares a theory invalid without proposing an alternative explanation for the clinical phenomena the theory seeks to organize is, by definition, incomplete.

We respectfully suggest that if Grossman and colleagues declare Polyvagal Theory untenable, the scholarly responsibility that follows is clear: offer a revised framework or propose a new one. The field deserves not only critique, but construction. Clinicians do not discard frameworks lightly. They move on from a model only when it is demonstrated to be harmful or when a stronger, more comprehensive alternative is made available.

PVT as an Evolving, Not Static, Framework

Since its original publication (Porges, 1995), PVT has undergone two major iterations (Porges, 2007, 2023), culminating in The Vagal Paradox: A Polyvagal Solution (Porges, 2023) and Polyvagal Perspectives: Interventions, Practices, and Strategies (Porges, 2024). The latest iteration employs the methodology of "strong inference" (Platt, 1964), systematically addressing contradictions in autonomic science and generating alternative hypotheses (Porges, 2025b). Porges (2025a) has explicitly stated that PVT "has generated a range of specific, testable predictions," including hierarchical recruitment of autonomic states under threat, the influence of social cues on vagal tone, and the effects of acoustic interventions on emotion regulation.

A theory that invites refinement is fundamentally different from a theory that resists it. PVT is not doctrine. It is a framework that generates testable hypotheses and should evolve alongside scientific discovery.

Impact Beyond the Therapy Room

PVT's influence extends well beyond individual psychotherapy. Its concepts have informed structural change across healthcare, education, trauma-informed schools, workplace wellness, leadership development, and community design (Porges, 2022; van Hooren et al., 2024). The framework helped move institutional cultures from punitive to supportive, from compliance-driven to safety-oriented. Schools began reorganizing discipline practices around nervous system regulation. Healthcare settings began recognizing that a patient's autonomic state affects their capacity to engage with treatment. In our own training programs at the Trauma Therapist Institute, we have seen clinicians fundamentally transform their case conceptualization and treatment planning when they begin understanding client presentations through the lens of autonomic state.

In a time defined by political polarization, chronic stress, social isolation, and burnout, PVT's emphasis on connection and co-regulation is not naive. It is protective. The framework supports community resilience, family stability, and workforce sustainability. The explosion of nervous system-informed work, somatic practices, state awareness, and trauma-informed systems did not happen in a vacuum. PVT created the conceptual container that made nervous system health accessible in mainstream care.

Theory and Misuse Are Not the Same Thing

An honest accounting requires acknowledging that some people oversimplify PVT. Some misuse its language. Some turn it into pop-psychology slogans or commercial branding that lacks scientific rigor. As the Polyvagal Institute has acknowledged, PVT has been adapted in wellness and coaching contexts that may not reflect the theory's actual depth or nuance.

That is not a failure of the theory. That is a failure of education and translational responsibility. It is essential to differentiate between a theory's empirical foundation and its public portrayal. Through the Trauma Therapist Institute, we have always positioned ourselves on the side of rigor, training clinicians not to parrot polyvagal language as shorthand but to understand the neurophysiology deeply enough to apply it with clinical precision and intellectual humility. When a critique of PVT is actually a critique of oversimplified applications, that distinction must be named.

Reframing the Critique: Valid, But Incomplete

My position is this: Grossman and colleagues raise valid scientific questions. They raise some legitimate criticisms, but those criticisms and evidence for such criticisms do not render PVT illegitimate. Further, they are evaluating anatomy while overlooking impact. They are measuring neural pathways while not accounting for clinical transformation, educational reform, cultural change, and system redesign. Both domains matter. Only one is being acknowledged in their analysis.

Declaring an entire theory "untenable" on the basis of mechanistic disagreements, while ignoring the clinical and systemic evidence that the theory has generated, is itself an incomplete evaluation. It also carries a responsibility that the Grossman paper does not meet: to offer an alternative framework, or updated framework, that accounts for the clinical phenomena PVT organizes. That framework has not been proposed.

Where We Stand

The Trauma Therapist Institute is not in the business of evangelism. We are translators of science, protectors of nuance, and advocates for evidence-informed practice that serves the real-world complexity of trauma.

We recognize that aspects of Polyvagal Theory’s evolutionary hierarchy may require refinement. Evolution is not a clean ladder. Neurobiology is not a staircase. The autonomic nervous system functions as an integrated, dynamic network rather than a rigid sequence of “new” systems inhibiting “old” ones. Scientific models mature. That is progress

And yet.

The widespread influence of Polyvagal Theory was never about anatomical diagrams alone. It was about what the model made visible.

PVT brought a generation of therapists and helping professionals into direct relationship with autonomic physiology. It offered an educational framework that helped clinicians understand how autonomic state shapes behavior, emotion, relational capacity, and health outcomes. It shifted the field from symptom management toward mechanism.

It gave us language for what many clinicians intuited but could not previously articulate: that safety is biological, that connection is regulatory, and that therapeutic relationship works not just psychologically — but physiologically.

Across decades of research, not limited to PVT, the significance of the vagus nerve in regulating cardiac function, inflammation, digestion, emotional state, and resilience is well established. While that body of research does not depend on Polyvagal Theory, PVT opened the door for many clinicians to engage it. It translated complex neurophysiology into a usable clinical lens.

We will continue to teach neuro-informed approaches to clinical work, drawing from research both within and beyond the sphere of Polyvagal Theory. Our commitment is not to a single model, but to helping clinicians understand autonomic physiology, recognize state-based presentations, and build therapeutic environments that support safety and regulation. As science evolves, so will our teaching as we integrate new findings, refine frameworks, and maintain the rigor that this field deserves. We welcome rigorous scientific discourse. We believe complexity can be held without collapse.

Polyvagal Theory is not sacred. It is significant.

It opened doors that were previously closed. It gave clinicians and systems a biological language for safety, connection, and healing. It made nervous system literacy accessible to those who needed it most.

That legacy remains, even as the model continues to evolve.

You can critique the wiring without dismissing the revolution.

Recommended Reading

The following primary sources are recommended for clinicians seeking to evaluate this debate independently:

Grossman et al. (2026): "Why the Polyvagal Theory is Untenable." Clinical Neuropsychiatry, 23(1), 100-112. Available at: https://doi.org/10.36131/cnfioritieditore20260110

Porges (2026): "When a Critique Becomes Untenable: A Scholarly Response to Grossman et al.'s Evaluation of Polyvagal Theory." Clinical Neuropsychiatry, 23(1), 113-128. Available at: https://doi.org/10.36131/cnfioritieditore20260111

Polyvagal Institute: Critiques of Polyvagal Theory: A Comprehensive Analysis. https://www.polyvagalinstitute.org/criticaldiscussionofpolyvagaltheory

Schwartz (2026): "Clinical Reflections on the Critique on Polyvagal Theory Proposed by Grossman et al. (2026)." https://drarielleschwartz.substack.com/p/clinical-reflections-on-the-critique

References

_{Byrne, E. A., & Porges, S. W. (1993). Data-dependent filter characteristics of peak-valley respiratory sinus arrhythmia estimation: A cautionary note. Psychophysiology, 30(4), 397-404. https://doi.org/10.1111/j.1469-8986.1993.tb02061.x}

_{Cozolino, L. (2014). The neuroscience of human relationships: Attachment and the developing social brain (2nd ed.). W.W. Norton. https://wwnorton.com/books/9780393707823}

_{Disability and Rehabilitation. (2024). Clinical application of transcutaneous auricular vagus nerve stimulation: A scoping review. Disability and Rehabilitation, 46(26), 5730-5760. https://doi.org/10.1080/09638288.2024.2313123}

_{Goggins, E., Mitani, S., & Tanaka, S. (2022). Clinical perspectives on vagus nerve stimulation: Present and future. Clinical Science, 136(9), 695-709. https://doi.org/10.1042/CS20210507}

_{Grossman, P. (2023). Fundamental challenges and likely refutations of the five basic premises of the polyvagal theory. Biological Psychology, 180, 108589. https://doi.org/10.1016/j.biopsycho.2023.108589}

_{Grossman, Paul. (2016). Re: After 20 years of “polyvagal” hypotheses, is there any direct evidence for the first 3 premises that form the foundation of the polyvagal conjectures?. Retrieved from: https://www.researchgate.net/post/After-20-years-of-polyvagal-hypotheses-is-there-any-direct-evidence-for-the-first-3-premises-that-form-the-foundation-of-the-polyvagal-conjectures}

_{Grossman, P., Ackland, G. L., Allen, A. M., Berntson, G. G., Booth, L. C., Burghardt, G. M., ... & Zucker, I. H. (2026). Why the polyvagal theory is untenable: An international expert evaluation of the polyvagal theory. Clinical Neuropsychiatry, 23(1), 100-112. https://doi.org/10.36131/cnfioritieditore20260110}

_{Grossman, P., & Taylor, E. W. (2007). Toward understanding respiratory sinus arrhythmia: Relations to cardiac vagal tone, evolution and biobehavioral functions. Biological Psychology, 74(2), 263-285. https://doi.org/10.36131/cnfioritieditore20260110}

_{Kase, R. (2023). Polyvagal-informed EMDR: A neuro-informed approach to healing. W.W. Norton. https://wwnorton.com/books/9781324030317}

_{Kase, R. (2023). The applied polyvagal flip chart. PESI Publishing.}

_{Kase, R. (2025). The Polyvagal Solution: Vagus nerve-calming practices to soothe stress, ease emotional overwhelm, and build resilience. New Harbinger. https://www.newharbinger.com/9781648484124/the-polyvagal-solution/}

_{Kozlowska, K., Walker, P., McLean, L., & Carrive, P. (2015). Fear and the defense cascade: Clinical implications and management. Harvard Review of Psychiatry, 23(4), 263-287. https://doi.org/10.1097/HRP.0000000000000065}

_{Lanius, R. A., Brand, B., Vermetten, E., Frewen, P. A., & Spiegel, D. (2012). The dissociative subtype of posttraumatic stress disorder: Rationale, clinical and neurobiological evidence, and implications. Depression and Anxiety, 29, 701-708. https://doi.org/10.1002/da.21889}

_{Lewis, G. F., Furman, S. A., McCool, M. F., & Porges, S. W. (2012). Statistical strategies to quantify respiratory sinus arrhythmia: Are commonly used metrics equivalent? Biological Psychology, 89(2), 349-364. https://doi.org/10.1016/j.biopsycho.2011.11.009}

_{Mendelowitz Lab. (2025). Oxytocin receptor expression and activation in parasympathetic brainstem cardiac vagal neurons. eNeuro, 12(8). https://www.eneuro.org/content/12/8/ENEURO.0204-25.2025}

_{Platt, J. R. (1964). Strong inference. Science, 146(3642), 347-353. https://doi.org/10.1126/science.146.3642.347}

_{Porges, S. W. (1995). Orienting in a defensive world: Mammalian modifications of our evolutionary heritage. A Polyvagal Theory. Psychophysiology, 32(4), 301-318. https://doi.org/10.1111/j.1469-8986.1995.tb01213.x}

_{Porges, S. W. (2007). The polyvagal perspective. Biological Psychology, 74(2), 116-143. https://doi.org/10.1016/j.biopsycho.2006.06.009}

_{Porges, S. W. Polyvagal Safety: Attachment, Communication, Self-Regulation. New York, NY: W. W. Norton & Company, 2021.}

_{Porges, S. W. (2022). Polyvagal theory: A science of safety. Frontiers in Integrative Neuroscience, 16, 871227. https://doi.org/10.3389/fnint.2022.871227}

_{Porges, S. W. (2023). The vagal paradox: A polyvagal solution. Comprehensive Psychoneuroendocrinology, 16, 100200. https://doi.org/10.1016/j.cpnec.2023.100200}

_{Porges, S. W. (2024). Polyvagal perspectives: Interventions, practices, and strategies. W.W. Norton. https://wwnorton.com/books/9781324053408}

_{Porges, S. W. (2025a). Polyvagal theory: Current status, clinical applications, and future directions. Clinical Neuropsychiatry, 22(3), 169-184. https://doi.org/10.36131/cnfioritieditore20250301}

_{Porges, S. W. (2025b). Polyvagal theory: A journey from physiological observation to neural innervation and clinical insight. Frontiers in Behavioral Neuroscience, 19, 1659083. https://doi.org/10.3389/fnbeh.2025.1659083}

_{Porges, S. W. (2026). When a critique becomes untenable: A scholarly response to Grossman et al.'s evaluation of Polyvagal Theory. Clinical Neuropsychiatry, 23(1), 113-128. https://doi.org/10.36131/cnfioritieditore20260111}

_{Schwartz, A. (2026, February 22). Clinical reflections on the critique on Polyvagal Theory proposed by Grossman et al. (2026). Substack. https://drarielleschwartz.substack.com/p/clinical-reflections-on-the-critique}

_{Strain, M. M., Conley, N. J., Kauffman, L. S., Espinoza, L., Fedorchak, S., Martinez, P. C., & Boychuk, C. R. (2024). Dorsal motor vagal neurons can elicit bradycardia and reduce anxiety-like behavior. iScience, 27(3), 109137. https://doi.org/10.1016/j.isci.2024.109137}

_{Tan, C., Qiao, M., Ma, Y., Luo, Y., Fang, J., & Yang, Y. (2023). The efficacy and safety of transcutaneous auricular vagus nerve stimulation in the treatment of depressive disorder: A systematic review and meta-analysis. Journal of Affective Disorders, 337, 37-49. https://doi.org/10.1016/j.jad.2023.05.015}

_{Tang, S. S. (2021). R.I.P. Polyvagal Theory. Medium. https://medium.com/@drshinshin/r-i-p-polyvagal-theory-897f935de675}

_{van Hooren, S., et al. (2024). A theoretical exploration of polyvagal theory in creative arts and psychomotor therapies for emotion regulation in stress and trauma. Frontiers in Psychology, 15, 1382007. https://doi.org/10.3389/fpsyg.2024.1382007}