Interoception is the ability to perceive one’s own internal bodily signals. In recent years, interoceptive abilities have been found to significantly impact mental health and affective states. Impaired interoception has been linked to a range of disorders including anxiety, PTSD, depression, eating disorders, Parkinson’s, Alzheimer's, and other neurodegenerative diseases, and physical conditions like impaired cardiac function, irritable bowel syndrome, and fibromyalgia, among others. Moreover, lower interoception was shown to be correlated with a tendency for developing psychopathology or poor mental health and has been associated with reduced mental resilience.

The perception of inner bodily signals is part of the sensory experience that makes up our understanding of the world. Similar to the exteroceptive senses (vision, hearing etc.) that are focused outwards, the interoceptive senses (awareness of one’s respiration, heartbeat etc.) are focused inwards. A body of research in cognitive psychology and neuroscience has explored the connections between the exteroceptive senses, via sensory substitution, which involves employing an alternate sense to convey information typically acquired by another sense (for example translating visual information to sound). 

In this paper, we propose drawing on principles of sensory substitution, by using the exteroceptive senses for conveying interoceptive information, and by doing so improving one's interoception. This approach aims to ultimately support emotional regulation and enhance overall well-being. To explore this, we developed a sensory substitution experience that conveys the user's breath through visual and auditory representations. For its evaluation, we also developed a new questionnaire, the Short State Interoceptive Sensibility Questionnaire (SSIS), designed to reflect one’s present interoceptive sensibility, as opposed to most existing measures designed to assess interoceptive sensibility as a persistent trait.

An exteroceptive-interoceptive experience - visual and auditory representations of the user's breath

The experience developed was set in a unique environment, with three screens surrounding the user for an immersive experience, and a spatial audio system (ambisonics), which allows for simulating the movement of sound in space. It was developed in collaboration with video art creator and multidisciplinary director Yoav Cohen. The experience centers around a multi-layered sphere. The sphere's behavior mirrors the user's breath in real time, expanding on inhalation and contracting on exhalation, while another layer follows it in a slight delay, giving it a more organic feel. This direct mapping imitates the behavior of the chest or lungs, creating a strong sense of embodiment and enhancing the connection between internal and external signals. The sphere’s inner layer is a glowing light that expands with exhalation, to encourage extended exhalations known to be associated with inducing relaxation. An additional visual effect designed for this purpose is a wave of light emitted from the center of the orb whenever the user extends their exhalation for longer than they had previously.

The auditory component includes ambient sounds circulating around the participant, and an additional sound coming from the heart of the sphere, designed to resemble the sound of ocean waves expanding. The sounds further synchronize in their auditory features and locations with the user's rhythm of breathing, reinforcing the connection between the interoceptive breathing signal and the exteroceptive stimulus.

These visual and auditory cues work together to create a cohesive, immersive experience that enhances the user's awareness of their internal bodily sensations.

Uncovering the potential of the exteroceptive-interoceptive approach 

We employed a battery of tests to measure interoceptive sensibility, flow, and mind wandering among other parameters. Our findings indicate that the system significantly enhances interoceptive sensibility and flow. Furthermore, a high correlation was shown between flow and interoceptive sensibility suggesting that users’ attention is redirected to their internal sensations due to the external stimuli. This indicates a strong bidirectional relationship between engaging with the immersive external representation of respiration and the awareness of internal bodily signals.

To evaluate interoceptive sensibility specifically, we developed the 15-item Short State Interoceptive Sensibility questionnaire. This questionnaire is designed to reflect one’s momentary interoceptive sensibility at a particular time, with interoceptive sensibility commonly regarded as one's subjective belief towards their ability to perceive interoceptive signals. We share this questionnaire openly with the research community, so that it can be validated and will continue to be used in interoception research going forward.

Given the well-established connection between interoception and well-being and the significance of flow in positive psychology, this method could support emotional regulation and improve overall mental health. The developed experience's ability to enhance interoceptive sensibility and flow suggests it could be used in stress management programs and emotional regulation therapies. By increasing awareness of internal bodily sensations, individuals may better manage stress and regulate emotions. The integration of interoceptive and exteroceptive processes aligns with mindfulness practices, such as breathing exercises and body scan meditation. This system and similar ones relying on the same principles could complement such practices, providing a more immersive and interactive experience that enhances the benefits of mindfulness. The concept also lends itself to potential therapeutic applications, as a tool for individuals with anxiety disorders, depression, or other mental health conditions.  

The potential of the exteroceptive-interoceptive approach could be much wider than the scope we currently explored. Interoception has also been connected to a broad range of functions related to social interaction and cognition, among them altruism, time perception, self-awareness, decision-making, and memory. As such, future research should explore diverse applications of exteroceptive-interoceptive sensory substitution. Moving beyond this implementation, we plan to explore other interoceptive signals and exteroceptive modalities, expanding the scope of this approach to cover a more extensive range of sensory experiences. Such research may enable both the development of new applications, and a better understanding of our sensory experience.

Related papers

Maimon, A., Yizhar, O., Buchs, G., Heimler, B., & Amedi, A. (2022). A case study in phenomenology of visual experience with retinal prosthesis versus visual-to-auditory sensory substitution. Neuropsychologia, 173, 108305. https://doi.org/10.1016/j.neuropsychologia.2022.108305

Wald, I. Y., Maimon, A., Keniger De Andrade Gensas, L., Guiot, N., Ben Oz, M., Corn, B. W., & Amedi, A. (2023, April). Breathing based immersive interactions for enhanced agency and body awareness: a claustrophobia motivated study. In Extended Abstracts of the 2023 CHI Conference on Human Factors in Computing Systems (pp. 1-7). https://doi.org/10.1145/3544549.3585897

Dobrushina, O. R., Tamim, Y., Wald, I. Y., Maimon, A., & Amedi, A. (2024). Training interoceptive awareness with real-time haptic vs. visual heartbeat feedback. bioRxiv, 2024-01. https://doi.org/10.1101/2024.01.12.575196