Close your eyes and try to feel your heartbeat without touching your wrist or your chest. Count the beats for thirty seconds. Some people can do this easily. Others find it nearly impossible.
That simple exercise tests something called interoception — the sense by which the brain perceives the internal state of the body. It is one of the most important senses you have, and until recently, one of the least studied. The last two decades of research have begun to reveal that interoception is not a curiosity. It shapes emotion, decision-making, and mental health in ways that may be more fundamental than we realized.
The body's own sense
You are familiar with your five external senses — sight, sound, touch, taste, and smell. Interoception is the internal one. It is the moment-to-moment perception of what is happening inside your body: heartbeat, breathing, hunger, thirst, bladder fullness, temperature, the subtle sensations of your gut, the tension in your muscles.
The signals come from a dense network of sensory nerves scattered throughout your organs. They travel up the vagus nerve and the spinal cord to a brain region called the insular cortex, where they are integrated into a running picture of your body's state. Neuroscientist A. D. "Bud" Craig, whose seminal work synthesized this research in How Do You Feel? (Princeton, 2014), argued that interoception is, in effect, the biological basis of feeling itself.
Interoception and emotion
Most of us, if asked what an emotion is, would describe a feeling. But where does that feeling come from?
One influential account, developed by neuroscientist Antonio Damasio in The Feeling of What Happens (1999) and refined by Lisa Feldman Barrett in How Emotions Are Made (2017), holds that emotions are largely the brain's interpretation of interoceptive signals. Your heart races, your breath quickens, your palms dampen — and your brain, drawing on context and learning, labels the pattern as fear, or excitement, or anger.
If this picture is right, interoception is not a sidebar to emotional life. It is the raw material of it. How accurately you perceive your body's signals — and what you do with that information — shapes what you actually feel.
Research bears this out. Studies using a simple heartbeat-detection task — asking participants to count their heartbeats silently over a set interval — find that people vary widely in their interoceptive accuracy. Those who are more accurate tend to report more intense and more differentiated emotional experiences. They also tend to perform better on certain decision-making tasks.
The Iowa gambling study
A striking example comes from Antoine Bechara and colleagues at the University of Iowa. In their well-known Iowa Gambling Task studies (Bechara et al., Cognition, 1994), participants chose cards from four decks — two "bad" decks with occasional large rewards but larger losses, and two "good" decks with smaller but steadier gains.
Healthy participants learned to favor the good decks long before they could verbally explain why. Before they had conscious insight, their bodies — measured through skin conductance — began to react with anticipatory stress when they reached for the bad decks. The body was already signaling danger while the mind was still guessing.
Patients with damage to specific brain regions involved in integrating bodily signals did not show this anticipatory response. They continued to lose money on the bad decks even after many rounds. Their reasoning was intact. What they lacked was the felt sense that the choice was wrong.
This is one of the more vivid demonstrations in neuroscience that we think with our bodies, not just our brains.
When interoception goes wrong
Interoceptive disruption shows up in a striking range of conditions.
Anxiety disorders. People with panic disorder often have heightened sensitivity to bodily signals but misinterpret them catastrophically — a racing heart becomes a looming heart attack. This is why cognitive behavioral therapy for panic often includes interoceptive exposure: deliberately inducing the sensations in a safe setting so the brain can re-learn that they are not dangerous.
Depression. Emerging research suggests people with depression show blunted interoceptive awareness, which may contribute to the numbness many describe.
Eating disorders. Individuals with anorexia and bulimia often have disrupted interoceptive signals around hunger and satiety. Some research suggests the disruption precedes the disorder rather than simply resulting from it.
Autism. A growing body of work, including studies by Sarah Garfinkel and colleagues, suggests that some autistic individuals have weaker interoceptive accuracy but stronger interoceptive sensibility (attention to body signals) — a mismatch that may contribute to the anxiety many experience.
Alexithymia. This is the technical term for difficulty identifying and describing one's own emotions. It correlates strongly with low interoceptive accuracy. People with alexithymia often have emotional responses but cannot read their own bodily signals well enough to name them.
Can interoception be trained?
The evidence is cautiously encouraging. Practices that involve sustained attention to the body — mindful breathing, body scan meditation, yoga, certain forms of dance and tai chi — appear to modestly improve interoceptive accuracy and change activity in the insular cortex.
A 2022 randomized trial by Cynthia Price and colleagues at the University of Washington tested an intervention called Mindful Awareness in Body-oriented Therapy (MABT) and found improvements in interoceptive awareness that correlated with reductions in anxiety and depression.
The mechanism is probably not mysterious. The brain learns what it attends to. If you spend almost no time noticing your body, the insular cortex does not get refined. If you spend a little time each day attending to breath, heartbeat, sensations of hunger and tension, you build the representation.
Why this matters outside the clinic
You do not need a disorder for this research to matter to you. Ordinary decision-making — what to eat, when to stop working, whether to trust a bad feeling about a situation — runs in part on interoceptive signals. People who ignore those signals can find themselves chronically exhausted, chronically anxious, or chronically making choices they later regret.
The body is not a passenger in your life. It is a participant in your thinking.
Interoception also matters relationally. Our capacity to perceive our own internal states is closely tied to our capacity to perceive others'. Studies repeatedly find that interoceptive accuracy correlates with empathy and emotion recognition in others.
The old Western habit of treating the mind as separate from the body — as though reason lived in the skull and the body was merely a vehicle — keeps getting harder to defend. The science of interoception is one of many reasons why. You feel with your heart, your gut, your skin, your lungs. The brain is not thinking despite all that. It is thinking through it.
The next time you notice a feeling you can't quite name, try slowing down and listening to what your body is actually reporting. You may find the answer was there all along — in the one sense most of us forget we have.
