Interoception: How the Body Speaks to the Brain
Interoception as a separate sense for the internal state of the body—how the experience of a bodily signal arises and what it means in the context of shibari.
· 19 min read
In previous texts, we discussed autonomic regulation, allostasis, and how the nervous system continuously predicts the organism’s needs. We also demonstrated that the resulting experience is not a direct imprint of an external stimulus or the bodily reaction itself. It emerges from the interplay of the organism’s current state, the situational context, prior experience, and expectations.
This text focuses on the process that connects these mechanisms with the perception of one’s own body: interoception.
Interoception refers to the way the nervous system detects, integrates, and interprets information coming from the organism’s internal environment. It is not just the conscious perception of heartbeat, breath, hunger, or tension. A large part of interoceptive processing occurs outside conscious attention and participates in the continuous regulation of bodily needs, emotions, attention, and action.
The autonomic nervous system and interoception are closely related, but they cannot be understood as two sequential phases of a single system. The autonomic nervous system is primarily involved in controlling organ functions, while interoception involves receiving and processing information about what is currently happening inside the organism.
Both processes form part of a broader regulatory loop. The brain influences the bodily state while continuously receiving information about the consequences of this regulation. Based on this, it can adjust further organismal activity before a person consciously realizes any change.
Afferent and Efferent Signaling
The difference between autonomic regulation and interoception can be illustrated through the direction of information flow.
Efferent signaling travels from the brain and spinal cord out to organs, blood vessels, glands, and other bodily structures. Through these pathways, the nervous system influences, for example, heart rate, blood circulation, digestion, or energy availability.
Afferent signaling runs in the opposite direction. Receptors in organs, blood vessels, muscles, and other tissues record mechanical, chemical, thermal, and metabolic changes and transmit information about them to the spinal cord and brain. Thus, the nervous system gathers data on pressure, tension, organ distension, blood chemical composition, energy availability, inflammatory activity, or internal temperature changes.
This distinction is useful, but it alone does not capture the entire relationship between both processes. Interoception is not merely the sum of afferent signals. It also involves their selection, integration, interpretation, and placement into a broader context.
The same physiological signal can be evaluated as a normal regulatory change, fatigue, pleasant arousal, pain, or a sign of threat, depending on the situation. Therefore, information coming from the body does not have a fixed meaning. Its meaning only emerges within the organism’s overall situation.
The frequent conflation of the autonomic nervous system and interoception is also related to their anatomical connection. The vagus nerve, known primarily as a major component of parasympathetic regulation, contains predominantly afferent fibers transmitting information from internal organs to the brainstem. Thus, it participates in both regulating organ functions and transmitting information about their current state.
Therefore, rather than labeling interoception a part of the autonomic nervous system, it is more accurate to understand both processes as interconnected parts of organism regulation. Autonomic outputs alter the bodily state, interoceptive signaling provides feedback, and the central nervous system adjusts further regulation based on it.
This loop runs continuously. Most of it remains outside consciousness, and only some changes become part of subjective experience.
What Interoception Includes
Interoception is often described as the sense of the body’s internal state. This definition is useful provided it doesn’t obscure the fact that it is not a single sensory channel with one type of receptor and one neural pathway.
Interoception is a set of processes that handle various kinds of bodily information. The nervous system monitors heart rate, blood pressure, the rhythm and depth of breathing, oxygen and carbon dioxide levels, temperature, digestion status, bladder fullness, visceral pain, fatigue, thirst, hunger, and energy availability.
Hormonal, metabolic, and immune signals also enter the picture of the internal state. These are transmitted not only via neural pathways but also through chemical communication within the organism. Interoception is thus part of a broader system where neural, endocrine, metabolic, and immune processes communicate.
It partially overlaps with other areas of bodily perception. Proprioception provides information about the body’s position and movement. Somatosensory processing includes touch, pressure, vibration, pain, and temperature on the body’s surface and in deeper tissues.
In actual experience, however, these systems do not function separately. A feeling of tightness in the chest can contain interoceptive information about a change in breathing, a somatosensory perception of pressure, proprioceptive information about posture, and the emotional meaning of the situation. Subjective experience arises from their combined processing.
Not all bodily changes enter consciousness. Most regulatory processes occur without the need for conscious attention. A person usually doesn’t perceive individual changes in blood pressure, hormonal concentrations, or digestive system activity, even though these processes affect their energy, mood, attention, and behavior.
A conscious bodily sensation is therefore not a simple imprint of a physiological state. It is the result of selection and integration. The nervous system amplifies some signals, suppresses others, and processes the rest solely at the level of automatic regulation.
Usually, changes that are currently relevant to the organism’s needs, expectations, or ongoing activity enter consciousness more prominently. The feeling of thirst can become urgent during fluid deprivation but might be temporarily suppressed during intense focus. Pain can dominate consciousness or, conversely, fade into the background for a time if attention and the situation require a different mode of action.
Interoception is therefore not just a matter of what is happening in the body. It also encompasses which bodily changes are allocated attention and what meaning the organism assigns to them.
From Bodily Signal to Experience
A bodily signal itself is not yet an emotion, nor is it unambiguous information about a situation’s meaning.
An increased heart rate can accompany physical exertion, anticipation, sexual arousal, joy, anxiety, or fear. A change in breathing can relate to movement, focus, pain, arousal, or an attempt to regulate the intensity of an experience.
The resulting experience only arises when the nervous system connects the bodily information with circumstances, attention, past experience, and available action possibilities. The organism continuously evaluates whether the change is expected, whether it matches the current situation, and whether it requires a further regulatory response.
Interoception is therefore not a neutral reading of the body. It is an active process in which the brain generates an ongoing estimate of what is happening in the organism and what that change means.
This estimate can be accurate, inaccurate, or incomplete. It is influenced by fatigue, stress, pain, prior experience, attentional focus, and learned interpretive patterns.
For example, a person might notice an accelerated heartbeat but fail to correctly identify its cause. They might attribute it to a threat even though it’s the result of physical exertion, or conversely, overlook it in a situation where the body is signaling overload. They might perceive tension but fail to distinguish whether it relates to anticipation, an uncomfortable position, worry, or a need to move.
Interoceptive processing therefore cannot be reduced to the intensity of the sensation. What is essential is the ability to notice the signal, differentiate it, contextualize it, and respond to it appropriately.
Neuroanatomical Basis of Interoception
Interoceptive information enters the central nervous system through multiple pathways.
Some signals from internal organs are carried by the vagus and other cranial nerves to brainstem structures. A significant role here is played by the nucleus of the solitary tract (nucleus tractus solitarii), which receives information about the state of the heart, blood vessels, and respiratory and digestive systems.
Other information arrives via spinal afferent pathways. These mediate, among other things, sensations of pain, temperature, mechanical pressure, and chemical changes in tissues.
Interoceptive processing, therefore, does not only begin in the cerebral cortex. Information is already sorted and linked with reflex and regulatory responses at the level of the spinal cord and brainstem. Many bodily changes thus influence organismic activity before a conscious sensation can arise.
At higher levels, the thalamus, hypothalamus, insular cortex, anterior cingulate cortex, somatosensory areas, amygdala, and other structures participate in processing. This is not an isolated center of interoception, but a distributed network connecting information about the bodily state with attention, motivation, memory, emotions, and decision-making.
A prominent role is attributed to the insular cortex. The posterior parts of the insula are involved in processing relatively specific bodily information, while its anterior parts connect them with context, expectations, and subjective meaning.
However, this division cannot be seen as a simple linear transition from a “pure” bodily signal to a finalized conscious feeling. Individual parts of the network communicate bidirectionally, and the resulting experience arises from their joint activity.
A.D. Craig’s influential concept describes the insula as a key area for creating a holistic picture of the current bodily state. Craig also proposed that the integration of interoceptive information might form one of the neural bases of emotional awareness and the subjective feeling of presence within one’s own body.
While this hypothesis has significantly influenced further research, it does not represent a definitive explanation of subjective experience. Conscious bodily perception depends on a broader network that also includes somatosensory, cingulate, and other areas.
Interoceptive Differences Among People
The ability to perceive and interpret bodily signals varies significantly among individuals. However, these differences cannot be described by a single scale from low to high interoception.
A person can be highly attentive to certain sensations but interpret them inaccurately. They might track breathing changes well but struggle to distinguish hunger, fatigue, or progressing overload. Another person might perceive bodily signals fairly accurately but may not trust them or be able to name them.
Research therefore distinguishes several different interoceptive dimensions:
- Interoceptive accuracy refers to performance on tasks that attempt to compare subjective perception with an objectively measured bodily process.
- Interoceptive sensibility refers to a person’s subjective belief about how well or intensely they perceive their body.
- Interoceptive awareness expresses how realistically a person can assess the accuracy of their own perception. It is thus a metacognitive ability to recognize when their estimate is reliable and when it is not.
These characteristics do not have to align. A person might be convinced they understand their bodily signals very well but achieve low accuracy on an experimental task. Another person might distinguish bodily changes quite accurately without trusting their perception.
Measuring interoception itself is methodologically difficult. Traditionally used tasks focused on heartbeat perception can be influenced by knowledge of one’s resting heart rate, time estimation, instructional phrasing, and the strategy used.
Furthermore, performance on one task may not indicate the ability to perceive other bodily systems. Accuracy in estimating heart rate therefore cannot automatically be equated with the overall ability to understand one’s own body.
The quality of attention is also crucial for practical experience. Bodily signals can be observed curiously, differentially, and without the need for immediate judgment. But they can also be monitored hypervigilantly, with a focus on potential danger.
In both cases, attention to the body may be pronounced, but the consequences will differ. Higher sensitivity to bodily changes is therefore not inherently advantageous.
The ability to notice subtle signs of fatigue, arousal, or overload and adjust behavior accordingly can be beneficial. But if heightened bodily attention is coupled with uncertainty or catastrophic interpretation, it can contribute to anxiety and other difficulties.
The deciding factor, therefore, is not just how many bodily signals a person perceives, but also how they handle them.
Interoception and Emotions
Interoception contributes to emotional experience, but it is not its sole source.
Emotions emerge in the interplay of bodily changes, attention, situational meaning, memory, expectations, and action possibilities. Bodily signals provide information about the current state of the organism, while their emotional meaning depends on the broader context.
According to predictive and constructionist models, the brain continuously generates hypotheses about the causes of bodily changes. It doesn’t just wait for ready-made information from the body; it interprets it through prior experience and the current situation.
The resulting emotion therefore does not arise as a mechanical translation of a specific physiological pattern. The exact same activation can be experienced as arousal, intense focus, or joy in a safe and expected context. In an unpredictable situation, a similar bodily state might be interpreted as a threat.
The difference lies not just in the physiology, but in the meaning the nervous system assigns to the change and the response options the person perceives.
Simultaneously, interoception contributes to the ability to distinguish between similar emotional states. A vague feeling of “tension” might, upon closer attention, include several distinct components: held breath, pressure in the chest, a clenched jaw, an elevated heart rate, anticipation, or a need to move.
Differentiating these components more precisely can facilitate an understanding of one’s own state. However, it does not automatically mean the experience will be more pleasant or easier to regulate.
Bodily awareness is primarily useful when coupled with the ability to respond to the perceived signals. The ability to register overload has limited value if the person cannot change, slow down, or end the situation.
Interoception is therefore inseparable from action, relational context, and the actual degree of influence over the course of the situation.
Attention to the Body and Its Development
The way a person perceives and interprets bodily signals is not entirely fixed. It can be influenced by experience, learning, and repeated practice.
However, this does not mean there is a simple procedure that universally increases interoceptive accuracy.
Mindfulness meditation, breathwork, and certain somatically oriented approaches can support the ability to notice bodily changes, distinguish their quality, and stay with them without immediate rejection or judgment.
Research fairly consistently captures changes in the subjective relationship to bodily sensations. Less clear are the results regarding the objectively measured accuracy of their perception.
The development of interoceptive perception, therefore, cannot be reduced to trying to feel the body as intensely as possible. More intense attention does not necessarily lead to more accurate interpretation. In some cases, it can actually amplify uncertainty, discomfort, or fear of bodily changes.
More important might be the ability to flexibly shift between attention to the body and attention to the environment, distinguish the quality of sensations, and regulate the degree of contact with them. A person does not need to be constantly turned inward to perceive and respect bodily signals.
Interoceptive learning also occurs through experiencing the consequences of one’s own actions. A person gradually learns the connections between certain bodily signals and what usually follows. For example, they learn to recognize early signs of fatigue, breath-holding, mounting stress, or the need to change position.
The accuracy of this learning depends on whether the signals can be safely monitored, verified, and linked to an appropriate response. If bodily manifestations are chronically ignored, invalidated, or punished, it can become harder to distinguish and trust them.
Conversely, an environment in which a sensation can be noticed, named, and acted upon can support more nuanced orientation within one’s own state.
Interoception and Altered States of Consciousness
At high intensity, the distribution of attention can shift. The external environment may partially fade into the background, and breath, heart rhythm, pressure, temperature, pain, tension, or the sensation of movement inside the body gain greater prominence.
Experience can then be organized less through verbal thought and more through bodily qualities.
Such a shift can be experienced as deeper contact with oneself, an altered perception of time, narrowing or broadening of attention, a weakening of the usual need to narrate the experience, or a temporary transformation of the relationship between the body and the sense of identity.
However, these phenomena do not share a single physiological mechanism and can appear in various states.
A change in the ordinary mode of consciousness does not inherently indicate whether the experience is safe or will be easily integrated afterward. A reduction in verbal thought can accompany focus and trust, but also overload or dissociative disconnection.
The deciding factor is not only the subjective depth of the experience, but also its trajectory, the possibility of communication, subsequent orientation, and the ability to integrate the experience.
The concept of surrender can be understood in this context as a phenomenological description of a state in which a person temporarily reduces the conscious effort to manage every aspect of the experience. Attention can shift from continuous planning and control to immediate bodily sensations.
However, this is not a strictly defined neurophysiological state, nor a complete cessation of safety monitoring. Even during intense surrender, the nervous system continues to process changes in the bodily state and surroundings.
The difference may lie in the fact that it isn’t necessary to consciously analyze every change and react to it immediately. Such a state is more easily accessible when a person perceives the situation as sufficiently predictable and has the experience that their signals will be received and respected.
The Context of Conscious Touch and Shibari
In the context of shibari, interoception is relevant because a significant portion of the experience arises through changes in bodily perception.
The rope creates pressure, tension, and differences in weight distribution. Restricted movement alters proprioceptive information, the breathing pattern, and the way a person perceives the boundaries of their own body. Touch, position, distance, and the presence of another person simultaneously influence attention and the meaning of the entire situation.
These stimuli, however, do not determine the resulting experience on their own. The nervous system interprets them within the context of expectations, past experiences, consent/agreements, the relationship, and the current ability to act.
The exact same pressure can be perceived as stabilizing in one situation and threatening in another. Movement restriction can support focus and surrender, but it can also trigger a need to escape.
Predictability therefore plays a crucial role. A person does not need to know every next step to feel safe, but they need to understand the basic framework of the situation and know how to communicate a change in their state.
The feeling of safety is not created solely by reassurance. It is also built by the repeated experience that bodily signals and expressed boundaries have a real impact on the subsequent course of events.
Interoceptive attention can intensify during shibari. A person may more acutely perceive their breath, pulse, the pressure of the rope, temperature changes, tingling, muscle tension, or the gradual onset of fatigue.
Such focus can make the experience more precise and differentiated. However, it does not automatically mean that all perceived changes will be correctly interpreted.
Intensity can simultaneously limit the ability to name and communicate bodily signals. A person might notice a change without being able to pinpoint its meaning. Their attention can also become so narrowed that they miss certain important signals or cannot distinguish them from expected intensity.
Interoception, therefore, cannot be considered a substitute for technical knowledge, continuous monitoring, or communication between those involved. A subjective feeling that everything is fine does not always match the actual state of tissues, nerves, or blood circulation.
Special attention is required to distinguish between deep focus and disconnection. In both cases, a person might speak less, slow their reactions, or seem distant. The meaning of these manifestations, however, can be vastly different.
Silence, stillness, or limited verbal response alone, therefore, cannot automatically be taken as a sign of trust or surrender. It is necessary to monitor the broader trajectory of the situation, the prior communication style, and changes in posture, breath, muscle tension, and responsiveness.
Crucial for a safe experience is the option to change the pace, position, or intensity, and the experience to end it if needed. This option doesn’t have to be used throughout the entire situation, but it must remain a real possibility.
It is precisely this real influence over the process that helps the nervous system distinguish between a voluntarily accepted limitation and helplessness. The subjective experience of control does not necessarily mean directly managing every step. It can also lie in the trust that a communicated signal will be received and lead to an appropriate change.
The quality of the relational space thus does not manifest solely in a feeling of closeness. It has specific regulatory consequences. It influences whether a person can pay attention to bodily sensations without having to constantly scan for potential threats, whether they can communicate uncertainty, and whether changes in intensity can be processed as part of a sufficiently predictable experience.
Shibari can provide an environment for more nuanced attention to the body and for exploring the relationship between intensity, limitation, trust, and agency. However, it cannot be simply stated that it inherently increases interoceptive accuracy or leads to better regulation.
The outcome depends on the specific form of the practice, the relationship between the people, their past experiences, technical competence, communication setup, and how the experience is subsequently processed.
Conclusion
Interoception is a set of processes through which the nervous system detects, integrates, and interprets information about the organism’s internal state. It is closely linked with autonomic, hormonal, metabolic, and immune regulation, but it cannot be equated with any of these systems.
A bodily signal does not enter consciousness as a finalized, unambiguous piece of information. Its meaning emerges in relation to the situation, expectations, prior experience, and action possibilities.
Interoception is therefore not just the ability to “hear the body.” It also includes the ability to distinguish bodily signals, tolerate their uncertainty, verify their meaning, and respond to them appropriately.
People differ in which bodily changes they notice, how accurately they interpret them, and how much they trust their perception. Heightened attention to the body can support orientation within one’s own state, but it can also amplify uncertainty or anxiety. What matters is not just the intensity of perception, but its quality, context, and connection to regulatory capacity.
In intense physical experiences, interoception can significantly shape shifts in attention, emotions, and the sense of self. In the context of shibari, it plays a role in how pressure, limitation, touch, breath, and the presence of another person are perceived.
However, the resulting experience does not stem from a single bodily or neural mechanism. It is the outcome of a dynamic interplay of physiological changes, attention, meaning, the relational framework, and real action possibilities.
It is precisely this interplay that allows us to understand why similar stimuli can lead to fundamentally different experiences. Intensity alone does not determine the depth, safety, or meaning of the experience. The deciding factor is how the organism processes it, what meaning it assigns to it, and whether the person remains in relationship with their body, the situation, and the other person within it.