Interoception is the sense of the body’s internal physiological state. Where proprioception tells you where your body is in space, interoception tells you what’s happening inside it: heart rate, breathing depth, gut motility, bladder fullness, temperature, hunger, thirst, and the diffuse signals of autonomic arousal that underlie what gets called “feeling.” A. D. Craig argued that interoception constitutes the physiological basis for subjective feeling states — it’s how the body knows its own condition [@craig2002].
Neuroanatomy of interoception
Interoceptive signals travel through two primary pathways:
The lamina I spinothalamocortical pathway carries signals from small-diameter afferent fibers (C and Aδ fibers) throughout the body. These fibers respond to temperature, tissue damage, metabolic state, visceral distension, and other physiological conditions. Their signals ascend through lamina I of the spinal dorsal horn to the ventromedial posterior nucleus of the thalamus, then project to the posterior and mid-insular cortex [@craig2002].
The vagal pathway carries signals from visceral organs — heart, lungs, gut, liver — through the vagus nerve to the nucleus of the solitary tract (NTS) in the brainstem, then to the parabrachial nucleus and onward to the insular cortex. Stephen Porges’ polyvagal theory describes how vagal afferent activity shapes not just autonomic regulation but social behavior and emotional experience [@porges2011].
Both pathways converge on the insular cortex, particularly the anterior insula, which Craig identified as the site where raw physiological signals are integrated into a coherent representation of the body’s current state — what he called the “sentient self.”
Interoceptive accuracy, sensibility, and awareness
Research distinguishes three dimensions of interoception [citation needed]:
Interoceptive accuracy — how well a person’s subjective report matches objective measurement. The heartbeat detection task is the classic measure: you count your heartbeats without taking a pulse, and researchers compare your count to actual cardiac output. Accuracy varies across individuals and correlates with emotional sensitivity and anxiety regulation.
Interoceptive sensibility — a person’s self-reported tendency to attend to interoceptive signals. High sensibility doesn’t guarantee high accuracy; some people believe they’re attuned to their bodies but aren’t measurably so.
Interoceptive awareness — the metacognitive dimension: how well a person’s confidence in their interoceptive judgments tracks their actual accuracy. High awareness means your confidence calibrates to your performance.
These distinctions matter clinically. Anxiety disorders often involve high interoceptive sensibility (hypervigilance to bodily signals) coupled with low accuracy (misinterpreting those signals). Dissociative conditions often involve low sensibility — a blunting of interoceptive input that reduces the felt sense of inhabiting a body.
Interoception and affect
Craig’s proposal — that interoception generates feeling states — has been supported by neuroimaging and clinical evidence. The anterior insula activates during experiences of disgust, pain, empathy, and uncertainty. Damage to the insula impairs the ability to recognize one’s own emotional states, not just the ability to detect physiological signals.
This connects interoception to the vault’s work on affect. If affect operates at the level of bodily potential — the capacity to act and be acted upon — then interoception is the sensory channel through which affect registers. The felt quality of anxiety, excitement, fatigue, or ease isn’t an interpretation layered on top of a neutral body; it’s the body’s own report of its autonomic and metabolic state. Somatic practices that train interoceptive acuity don’t just improve body awareness — they change the resolution at which affect is experienced.
Interoception and information-theoretic stability
The neurophysiological embodiment of information-theoretic stability describes autonomic regulation as precision-weighted descent on free energy. Interoceptive signals provide the error terms in this process: the difference between predicted and actual physiological state drives corrective autonomic responses. High interoceptive accuracy means the prediction-error signal is clean; low accuracy means the system operates on noisy data, which degrades stability.
This formalization connects somatic practice to the vault’s information-theoretic framework. Training interoceptive acuity — through breathwork, body scanning, or somatic experiencing — doesn’t just produce subjective calm. It improves the precision of the signals that autonomic regulation depends on, moving the system toward the stability manifold that the information-theoretic model describes.
Related concepts
- Proprioception — the complementary sense of body position in space
- Somatic Awareness — the integrative capacity that draws on both interoception and proprioception
- Somatic Experiencing — a trauma approach that works through interoceptive tracking
- Reiki — a healing practice in which practitioners attend to interoceptive and energetic signals during treatment
Sources
- Craig, A. D. (2002). “How do you feel? Interoception: the sense of the physiological condition of the body.” Nature Reviews Neuroscience, 3(8), 655–666 [@craig2002].
- Porges, S. W. (2011). The Polyvagal Theory. Norton [@porges2011].
- Senn, E. (2025b). Stability Dynamics in Cognitive Systems: A Predictive-Processing Interpretation. arXiv:cs.AI [@senn2025b].