Is interoception a single function or a set of separable submodalities, and what does evidence from cardiac, respiratory, and gastric channels show?

Why the heart, lungs, and stomach may not share one interoceptive ability

The strongest evidence for separability comes from comparing how well the same people perform across different bodily channels. In one study, participants completed tasks tapping cardiac awareness, temperature detection, affective touch, and pain. Accuracy on these tasks did not correlate across submodalities, with the exception of cold and pain perception in the palm, suggesting that interoception at the perceptual level is a set of relatively independent processes rather than a single construct [4].

A study of cardiac and gastric interoception reached a similar but more nuanced conclusion. Cardiac and gastric measures were distinguishable, yet not entirely independent, meaning the channels can be separated but may still share some common ground [5]. This matters because it argues against both extremes: interoception is neither one undifferentiated sense nor a collection of completely unrelated abilities.

The brain couples to each visceral rhythm separately

A direct test of whether visceral signals act independently came from measuring motor corticospinal excitability while simultaneously recording cardiac, respiratory, and gastric rhythms. All three rhythms were coupled to motor excitability with similar effect sizes at the group level, but participants who showed strong coupling with one organ did not necessarily show strong coupling with the others [1]. That pattern is consistent with independent mechanisms underlying each channel rather than a single shared interoceptive driver.

The same study found that these objective coupling strengths were not explained by participants' self-reported awareness of the organ [1]. In other words, how strongly a person's brain responds to their heartbeat or stomach rhythm is not simply a matter of how much they believe they notice those signals. This supports the idea of individual interoceptive profiles: each person may have a different pattern of strengths across channels.

A framework with two modes, and what it leaves open

One proposed framework distinguishes two modes of interoceptive signaling: an information mode and a coordination mode, drawing on evidence from cardiac, respiratory, and gastric channels [2]. The idea is that interoception may serve different functions depending on whether the brain is extracting information about bodily state or coordinating bodily rhythms with other processes. This remains a framework rather than a settled finding, but it helps explain why separate channels could still interact in organized ways.

The clinical relevance of separating channels is illustrated by disordered eating. In a study of 128 participants, gastric interoception was a stronger predictor of emotional, external, and restrained eating than cardiac interoception, with gastric attribution of sensations playing the most important role [5]. If interoception were a single general ability, cardiac and gastric measures should have predicted eating behavior similarly; instead, the stomach channel carried more weight.

Music research offers a further example of channel-specific measurement. A study using simultaneous EEG, respiration, and ECG estimated cardiac interoception via the heartbeat evoked potential and respiratory interoception via respiratory modulation of neural activity, treating them as distinct dimensions during affective music listening [3]. That design reflects the broader shift toward measuring interoception channel by channel rather than as one score.

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