Your Body Doesn't Know If You're Scared or Excited

Two people, two hallways, roughly one physiology. The first is standing in the wings before a keynote, heart at 110, palms damp, breath high in the chest, stomach doing something unhelpful. The second is in the queue for a rollercoaster with the same heart rate, the same damp hands, the same high shallow breathing. One is bracing. The other is grinning at a friend.

If fear, excitement, awe, and joy can be assembled from overlapping bodily ingredients, the interesting question is not what the body is doing. It is where the emotion actually comes from. That question turns out to have several answers stacked on top of one another.

The dominant answer in current work is that the brain does not read emotion off physiology like a gauge. It predicts what the body should be doing and what the world is likely doing, then infers emotional meaning from how those predictions fit together and where they miss (Seth & Friston, 2016; Feldman et al., 2024). Interoceptive predictions, meaning the brain's expectations about signals from inside the body, form one stream inside a larger multimodal expectation about being this self in this situation (Seth, 2013). Physiology is an input to that inference, not the verdict.

A qualification belongs here before the idea runs away. Bodily states are not perfectly undifferentiated, and the strong constructionist reading is contested rather than settled. What the evidence supports more securely is that peripheral arousal underdetermines emotional experience, so the same or highly similar profile can be interpreted in more than one way depending on what else is going on (Feldman et al., 2024; Critchley & Garfinkel, 2017). Ambiguity, not identity, is the claim doing the work.

So what resolves the ambiguity? Situation, first. Koban and colleagues (2021) describe compressed multimodal situation models, meaning internal representations that pull together sensory input, goals, motives, memories, and bodily signals into a working account of what is happening right now. These models do double duty: they guide what you perceive and they shape autonomic control, so the interpretation and the physiology are not fully independent of each other. The person in the queue has a model in which a fast heart is the point of the exercise.

Culture and concepts supply the categories that situation models use. Barrett and colleagues (2019) reviewed a large literature on facial movements and argued that the mapping from expression to emotion is far more variable across cultures, contexts, and individuals than common assumptions allow, which undercuts the idea of universal readable emotional displays. Their conclusions have been debated and the field has not reached consensus. What survives the debate is that context and perceiver both contribute to what a cue means, rather than the cue carrying its meaning intact.

Bodies, incidentally, may be more informative than faces. De Gelder (2006, 2009) argued for taking emotional body language seriously in affective neuroscience, partly because whole-body posture and movement specify likely action more directly than an isolated facial configuration does. A hunched, retreating body tells you something about what is about to happen. Language then layers on top of all this, giving people shared labels for internal states and shaping how those states get reported, remembered, and communicated (Critchley & Garfinkel, 2017).

The most persuasive demonstration that meaning changes bodily experience comes from placebo research. Wager and Atlas (2015) framed placebo effects as the meeting point of context, learning, and health, and Geuter and colleagues (2017) described the mechanism as expectation and learning working through descending control over autonomic and other peripheral systems. This is not merely reported relief. Expectations recruit real physiological change, which is why nocebo effects, where negative expectations worsen symptoms, are equally instructive and clinically bothersome (Rossettini et al., 2020).

Ashar and colleagues (2017) proposed an affective appraisal account of these effects, situating them in integrative systems centered on ventromedial prefrontal cortex and overlapping default-mode regions. Appraisal here means an evaluation of what a state implies for your well-being going forward, which requires memory, prospection, and valuation rather than sensation alone. That the same neural territory supports self-referential thought and future simulation is suggestive. A pain that means healing is genuinely not the same experience as an identical signal that means deterioration.

Personal narrative is the last widening of the circle. Koban and colleagues (2021) describe self-related processing as extending from physiological regulation up to a metacognitive narrative self, the ongoing story a person maintains about who they are and what their life is doing. Seth (2013) makes a compatible point about embodied selfhood arising from interoceptive inference rather than sitting above it. Someone who has learned that racing hearts mean impending humiliation is bringing a different model to that hallway than someone who has learned they mean readiness.

Clinically, this reframes what dysfunction looks like. Paulus and colleagues (2019) describe an active inference approach to interoceptive psychopathology, in which conditions such as anxiety and panic involve miscalibrated predictions about bodily states rather than simply excessive arousal. Quadt and colleagues (2018) note that healthy inference draws on prior experience, situational context, and precision weighting, meaning how much confidence the system assigns to a given signal or prediction. When precision is assigned badly, ordinary bodily noise can be read as evidence of catastrophe.

Which points somewhere practical. If emotion emerges from an inference about why the body is behaving this way, then regulation has a second lever, and it is not the one most people reach for first. You can try to change the physiology, through breath, sleep, movement, medication. Or you can work on the model that explains the physiology, which is closer to what reappraisal, exposure, and good therapeutic reframing are actually doing.

The keynote speaker and the rollercoaster rider will never fully swap places. Still, the distance between them is smaller than it feels, and much of it lives in the explanation rather than the pulse. Sometimes the useful question is not how do I stop my body doing this, but what does my brain currently think this means.

References

Ashar, Y. K., Chang, L. J., & Wager, T. (2017). Brain mechanisms of the placebo effect: An affective appraisal account. Annual Review of Clinical Psychology, 13, 73-98. https://doi.org/10.1146/annurev-clinpsy-021815-093015

Barrett, L. F., Adolphs, R., Marsella, S., Martinez, A. M., & Pollak, S. (2019). Emotional expressions reconsidered: Challenges to inferring emotion from human facial movements. Psychological Science in the Public Interest, 20, 1-68. https://doi.org/10.1177/1529100619832930

Critchley, H., & Garfinkel, S. (2017). Interoception and emotion. Current Opinion in Psychology, 17, 7-14. https://doi.org/10.1016/j.copsyc.2017.04.020

De Gelder, B. (2009). Why bodies? Twelve reasons for including bodily expressions in affective neuroscience. Philosophical Transactions of the Royal Society B: Biological Sciences, 364, 3475-3484. https://doi.org/10.1098/rstb.2009.0190

Feldman, M., Bliss-Moreau, E., & Lindquist, K. A. (2024). The neurobiology of interoception and affect. Trends in Cognitive Sciences, 28, 643-661. https://doi.org/10.1016/j.tics.2024.01.009

Gelder, B. (2006). Towards the neurobiology of emotional body language. Nature Reviews Neuroscience, 7, 242-249. https://doi.org/10.1038/nrn1872

Geuter, S., Koban, L., & Wager, T. (2017). The cognitive neuroscience of placebo effects: Concepts, predictions, and physiology. Annual Review of Neuroscience, 40, 167-188. https://doi.org/10.1146/annurev-neuro-072116-031132

Koban, L., Gianaros, P., Kober, H., & Wager, T. (2021). The self in context: Brain systems linking mental and physical health. Nature Reviews Neuroscience, 22, 309-322. https://doi.org/10.1038/s41583-021-00446-8

Paulus, M., Feinstein, J. S., & Khalsa, S. (2019). An active inference approach to interoceptive psychopathology. Annual Review of Clinical Psychology, 15, 97-122. https://doi.org/10.1146/annurev-clinpsy-050718-095617

Quadt, L., Critchley, H., & Garfinkel, S. (2018). The neurobiology of interoception in health and disease. Annals of the New York Academy of Sciences, 1428. https://doi.org/10.1111/nyas.13915

Rossettini, G., Camerone, E., Carlino, E., Benedetti, F., & Testa, M. (2020). Context matters: The psychoneurobiological determinants of placebo, nocebo and context-related effects in physiotherapy. Archives of Physiotherapy, 10. https://doi.org/10.1186/s40945-020-00082-y

Seth, A. (2013). Interoceptive inference, emotion, and the embodied self. Trends in Cognitive Sciences, 17(11), 565-573. https://doi.org/10.1016/j.tics.2013.09.007

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