You know the five senses. You may know proprioception — the sense of where your body is in space. You might even know the vestibular sense — balance and spatial orientation. But there's an eighth sense that neuroscience now considers foundational to everything from emotional intelligence to mental health to decision-making: interoception.
Interoception is the perception of internal body states — heartbeat, breath, gut activity, muscle tension, temperature, hunger, pain, and the thousands of subtle physiological signals that your body generates every second. It's the sense that tells you something "feels wrong" before you can articulate what it is. It's the foundation of gut feelings, emotional awareness, and the subjective experience of being alive in a body.
And the neuroscience behind it is reshaping how we understand the mind.
The Brain's Body-Sensing System
Interoceptive signals travel from organs and tissues throughout the body via two primary pathways. The vagus nerve carries information from the viscera — heart, lungs, gut, liver — to the nucleus of the solitary tract in the brainstem. Simultaneously, small-diameter afferent fibers (A-delta and C fibers) in the skin, muscles, and fascia carry signals about temperature, pain, itch, sensual touch, and tissue state through the spinal cord to the brain.
Both pathways converge on a single brain region: the posterior insular cortex. From there, interoceptive information flows forward through the insula to the anterior insular cortex (AIC), where it undergoes progressive integration with emotional, cognitive, and motivational data.
Neuroscientist A.D. (Bud) Craig has proposed that the AIC creates a moment-by-moment representation of "how you feel" — a neural image of the body's state that underpins subjective awareness itself. In Craig's model, interoception isn't just one sense among many. It is the physiological foundation of conscious experience.
"The anterior insular cortex provides a neural basis for the subjective image of the material self as a feeling entity — the 'material me.' It represents the primary neural substrate for awareness." — A.D. (Bud) Craig, Barrow Neurological Institute
The Insular Cortex: Where Body Becomes Mind
The insular cortex — a region of the brain folded deep within the lateral sulcus, hidden from view on the brain's surface — is the central hub of interoceptive processing. It's also one of the most connected regions in the entire brain, with projections to the amygdala, prefrontal cortex, anterior cingulate cortex, somatosensory cortex, and limbic system.
The insula operates as a hierarchical processing pipeline:
- Posterior insula: Receives raw interoceptive data — heart rate, breathing rhythm, gut signals, muscle tension. This is the "objective" body map.
- Mid-insula: Integrates interoceptive data with contextual information — where you are, what you're doing, what's happened recently. This produces body sensations that are contextualized by circumstance.
- Anterior insula: Integrates everything — body state, emotion, context, memory, social information — into a unified subjective feeling. This is where "I feel anxious" or "something feels right" emerges as a conscious experience.
Key Insight
The insular cortex processes body sensations into conscious feelings through a posterior-to-anterior pipeline. The anterior insula — where body state meets emotion and context — may be the neural basis of subjective awareness itself.
The Somatic Marker Hypothesis Revisited
Antonio Damasio's somatic marker hypothesis, first proposed in the 1990s, argued that body signals are essential for decision-making. But the mechanism he described is fundamentally interoceptive: the brain uses the body's internal state as a source of information about the value of different choices.
When you're faced with a decision, your brain doesn't just run logical calculations. It simulates the potential outcomes of each option and monitors the body for its response. Option A produces a subtle tightness in the chest. Option B generates a feeling of expansion and ease. These somatic markers — perceived through interoception — tag decision options with emotional valence, guiding choice in ways that pure logic cannot.
Damasio's patients with vmPFC damage couldn't use somatic markers because the brain region that processes interoceptive data in the context of decision-making was destroyed. They could reason but couldn't feel their way to good decisions. The result was rational analysis without wisdom — and consistently catastrophic choices.
Research has since confirmed that interoceptive accuracy — how well you can perceive your own body signals — directly predicts decision-making quality. A 2010 study by Barnaby Dunn and colleagues found that traders with higher interoceptive accuracy (measured by heartbeat detection tasks) made more profitable decisions and survived longer in the markets. Their gut feelings were literally making them better at their jobs.
Interoceptive Accuracy and Emotional Intelligence
Here's a finding that has profound implications: people who are better at perceiving their own body signals are better at understanding and regulating their emotions.
Research by Sarah Garfinkel at the University of Sussex has shown that interoceptive accuracy — typically measured by asking participants to count their heartbeats without touching their pulse — correlates with:
- Emotional granularity: High interoceptors can distinguish between subtly different emotional states (frustration vs. anger, nervousness vs. excitement), while low interoceptors experience emotions as undifferentiated arousal ("I feel bad")
- Emotional regulation: High interoceptors detect emotional states earlier, when they're still manageable, rather than only noticing emotions when they've escalated to full intensity
- Empathy: People who are attuned to their own body signals are better at reading emotional cues in others — possibly because empathy involves simulating others' body states in your own body
- Intuitive decision-making: High interoceptors make better use of gut feelings, trusting and acting on body-based information that low interoceptors miss
The relationship between interoception and emotion is not just correlational — it may be constitutive. The constructionist theory of emotion, developed by Lisa Feldman Barrett, proposes that emotions are not triggered but constructed by the brain from three ingredients: interoceptive data (what the body is doing), contextual information (what's happening in the environment), and prior experience (what has happened in similar situations before). In this model, interoception isn't a component of emotion — it's the raw material from which emotion is built.
"An emotion is your brain's creation of what your body sensations mean, in relation to what is going on around you in the world." — Lisa Feldman Barrett, PhD, Northeastern University
Gut Feelings as Neural Signals
The phrase "gut feeling" turns out to be neurologically precise. The enteric nervous system in the gut sends a continuous stream of afferent signals through the vagus nerve to the brain. These signals — about gut motility, microbiome metabolite levels, inflammatory markers, and mechanical distension — are processed interoceptively and contribute to the feeling of "rightness" or "wrongness" about a situation.
Research by Emeran Mayer at UCLA has shown that gut-to-brain signals influence mood, anxiety, and cognitive processing through interoceptive pathways. When participants in his studies experienced gut inflammation, they reported increased anxiety and negative emotional bias — not because they were conscious of their gut state, but because their interoceptive system was processing the gut's distress signals and coloring their emotional experience.
This means that a gut feeling isn't mystical intuition — it's your enteric nervous system providing data that your brain processes below conscious awareness. The quality of your gut feelings depends on the health of your gut (which determines the clarity of its signals) and your interoceptive accuracy (which determines how well your brain reads those signals).
When Interoception Goes Wrong
Disrupted interoception is now recognized as a feature of numerous mental health conditions:
- Anxiety disorders: People with anxiety often have heightened interoceptive sensitivity — they feel normal body signals (heartbeat, breathing) as threatening or abnormal, triggering panic responses to benign physiological events
- Depression: Depression is associated with reduced interoceptive accuracy — an inability to clearly perceive body states, which contributes to emotional numbness and difficulty identifying feelings (alexithymia)
- Eating disorders: Anorexia nervosa is characterized by profoundly disrupted interoception — inability to accurately perceive hunger, fullness, and body size. Research has shown that people with anorexia have altered insular cortex function
- PTSD and dissociation: Trauma can produce either interoceptive hypervigilance (constantly scanning the body for threat) or interoceptive shutdown (disconnection from body sensation as a protective mechanism)
- Autism spectrum conditions: Research has found atypical interoceptive processing in autism, which may contribute to difficulties with emotional regulation and social communication
Key Insight
Disrupted interoception is now linked to anxiety, depression, eating disorders, PTSD, and autism. Interventions that improve interoceptive accuracy — mindfulness, breathwork, somatic movement — may address these conditions at a foundational level.
Training Interoception
Unlike the traditional five senses, interoception can be systematically trained. Research has identified several practices that improve interoceptive accuracy:
- Body scan meditation: Progressively directing attention to different body regions builds the neural circuits for interoceptive awareness. fMRI studies show that experienced meditators have greater insular cortex activation and gray matter density
- Breath awareness: Simply attending to the sensations of breathing — without changing the breath — activates the anterior insula and strengthens interoceptive pathways
- Heartbeat perception training: Practicing awareness of your heartbeat (without touching the pulse) improves interoceptive accuracy over time and has been used therapeutically in anxiety treatment
- Somatic movement practices: Feldenkrais, tai chi, yoga, and other awareness-rich movement practices enhance proprioceptive and interoceptive sensitivity simultaneously
- Floating (sensory deprivation): Research by Justin Feinstein at the Laureate Institute has shown that flotation therapy dramatically enhances interoceptive signals by removing external sensory input, allowing participants to perceive their heartbeat, breathing, and gut activity with unusual clarity
Why This Matters
Interoception is not an esoteric concept. It is the mechanism through which the body informs the mind. Every emotion you feel is built from interoceptive data. Every gut feeling you follow is a processed interoceptive signal. Every decision you make is tagged by somatic markers that arise from interoceptive processing.
When interoception is accurate, you experience clear emotions, reliable intuition, and sound body-informed judgment. When it's disrupted — through chronic stress, trauma, sedentary behavior, or simple lack of attention — you lose contact with the body's intelligence, becoming disconnected from the very signals that make good decisions possible.
The science of interoception is the science of what happens when you learn to listen to your body — and what happens when you don't.
Key Takeaway
Interoception — the perception of internal body states — is the foundation of emotional experience, decision-making, and self-awareness. It can be trained through body scan meditation, breath awareness, somatic movement, and attention to internal sensation. Improving interoception improves everything downstream: emotion, intuition, and judgment.