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Vagus Nerve
Polyvagal Theory—Useful Narrative but Still Just a Theory
Polyvagal Theory oversimplifies complex issues and has limited empirical support
Posted September 30, 2022 Reviewed by Davia Sills
Key points
- Polyvagal Theory (PVT) is a popular approach to explaining how neurophysiology can impact our emotional states.
- PVT may be helpful at guiding treatments to attend to physiological and emotional states.
- Criticisms of Polyvagal Theory include concerns that it oversimplifies heterogeneous emotional reactions and makes hypothetical leaps.
- Clinicians and coaches using PVT should recognize that this is an experimental theory and practice good informed consent.
Many mental health therapists and coaches have a limited understanding of neurochemistry and neurophysiology. So, I get concerned when I hear such professionals talk confidently about the psychological effects of things such as dopamine or explain to patients how their nervous system is impacting their emotional functioning. Some therapists don’t read scientific literature but get their information from the same places as the general public—social media, mainstream media, and videos. If we’re lucky, therapists get more reliable, scientifically grounded, and up-to-date information from attending continuing education training. But even such training is highly susceptible to promoting the latest psychological fad because it increases ticket sales.
Polyvagal Theory (known as PVT) is one of these latest psychological fads, with lots of buzz and attention from therapists and coaches. This is especially apparent on social media platforms like TikTok, where the #polyvagal hashtag is extremely popular, with dancing, music, and body movements all recommended as interventions for everything from depression to trauma.
Polyvagal Theory was introduced in the 1990s by behavioral neuroscientist Stephen Porges. Porges focused on the vagus nerve, a cluster of nerves that start at the base of the brain and form a central component of the parasympathetic nervous system. If you remember your high school biology class, our bodies have a sympathetic nervous system, which activates our body in fight-or-flight-type situations. The parasympathetic nervous system works to calm those physiological reactions. Porges proposed that there was also a third system, a hybrid form of activation and calming, enacted during social engagement with other people.
Porges incorporated evolutionary theory into his model, arguing that the nervous system is constructed in a manner that reflects evolutionary development and that, when faced with danger, our bodies and minds can react, using evolutionarily older, less developed parts of our nervous system. Porges framed the term “neuroception” to describe our instinctual, unconscious assessment and perception of danger. In the face of some dangers, we freeze and become immobile, but in response to other situations, we may react with social engagement or soothing strategies to calm others and ourselves.
Heart Rate Variability (HRV) is a core component of Polyvagal Theory, where the variability in the time between heartbeats is an indication of the level of activation in response to threat or social engagement and an indicator of the body going into a state of immobility in response to overwhelming threat.
PVT also incorporates theories linking facial expressions and recognition of facial expressions into these nervous system states and linking a person’s level of facial expression with their ability to detect auditory cues of threats in the environment.
All of these theories come together in informing therapies that before one can change how they feel, they must change their nervous system state through techniques using breathing, social engagement, yoga, movement, and even music. Porges suggests: “Good therapy and good social relations, good parenting, good teaching, it’s all about the same thing—how do you turn off defensiveness? When you turn defense systems off, you have accessibility to different cortical areas for more profound understanding, learning, and skill development.”
The PVT approach is an interesting consolidation of different theories, observations, and concepts, creating a systemic conceptual framework to explain complex aspects of human physical and psychological reactions. Porges is a thoughtful scholar who weaves together disparate concepts in a compelling narrative.
Unfortunately, Polyvagal Theory has strong critics who challenge many core assumptions of the model. The notion that different parts of the vagal nerve and the nervous system reflect different levels of evolutionary development is strongly contested. Structures and functions that Porges identifies as more evolved are notably present in the physiology of animals such as lungfish, which show little evolutionary sophistication. There’s also quite a bit of hypothesizing going on, such as the speculation that certain reactions (freezing) are more evolutionarily primitive.
In PVT and in Porge’s research, respiratory sinus arrhythmia, referred to as vagal tone in PVT, is used as a measure of dysfunction and an indicator of the degree to which psychopathology is linked to the effects of the vagal nerve. However, a meta-analysis of the relationship between RSA and psychopathology found weak, highly inconsistent links between the conditions. A small (n=29) study by Porges and colleagues recently found that RSA differences were noticeable in people who were abstaining from alcohol versus those who were not and may be indicators of the physiological mechanisms underlying different cognitive and emotional effects related to consuming or abstaining from alcohol.
Critics of PVT argue that the model contains so many vague concepts with few precise predictions that it cannot be tested as a scientific theory. In that, the PVT model may be unfalsifiable, with less clear value as a scientific theory.
PVT may oversimplify complex nuances in human emotions and reactions and ignore the heterogeneity in internal experiences, leading people to overfocus on perceptions of threat. Patrick Lockwood, a psychologist and writer on fear, shared by email:
“Demystifying neuroscience is great, but oversimplifying it too much is typically problematic for clinicians, researchers, and patients. For instance, there exists great diversity of neuroanatomical 'causal' differences in responsivity to social and emotional information across people based upon, for example, their personality/temperament (e.g., high trait neuroticism), irrespective of trauma. Neurodivergent persons, such as individuals diagnosed with Autism Spectrum Disorder, will also be built differently and 'regulated' by social cues very differently irrespective of neuroception for 'safety' (Principle 4 of PVT). PVT also fails to recognize current research on reactions to threat, which include more than just fleeing or freezing, but include additional responses such as fawning and submission.”
Psychology fads often have little objective scientific research supporting them. PVT has very few empirical studies examining whether applications of polyvagal theory generate measurable positive clinical outcomes. One interesting study found that heart rate variability positively predicted patients’ perception of therapeutic alliance in a small sample of 53 participants. A few studies with a randomized control design have explored different intervention strategies, such as yoga and music therapy, and shown positive outcomes. However, these trials are evaluations of specific interventions that already existed prior to PVT, and they don’t clearly demonstrate that PVT itself is a model that outperforms others, or placebos, in guiding treatment. Most publications on PVT are reviews and hypothetical applications of the model to explain phenomena.
Polyvagal theory, especially with its theories regarding the hierarchical model of brain development and the inclusion of music and physical activities as a therapeutic intervention, is similar to various faddish clinical models of recent years, such as models drawn from attachment theories.
But each new iteration of these fads gives clinicians new language and ideas to use with patients, to help them re-examine themselves, their lives, choices, and problems. The attention to neuroanatomy may assist patients in creating some cognitive distance from their emotions, such that they can slow down, examine them, and implement mindful strategies to self-regulate.
Clinicians learning about PVT is probably beneficial, though they should be aware of the limited overall support and conceptual problems that currently exist in Polyvagal Theory. The use of PVT in therapy is highly experimental at this point, and therapists should ethically communicate that to patients. PVT may oversimplify important aspects of emotions and physiological reactions. Unfortunately, I doubt most clinicians using PVT in therapy are giving adequate informed consent (and coaches may be doing far less).
