Interoception is a term used to describe the human ability to sense the internal state of our bodies.
Decidedly different from the 5 senses we learned in school, the sensory receptors that contribute to interoception (called, unsurprisingly, "interoceptors") are located much deeper in the body, typically in the walls and fascia surrounding our internal organs and vessels. These sensory receptors:
Help regulate homeostasis of our internal environments
Signal to our brains when it's time to eat (hunger)
Signal to our brains when it's time to use the bathroom (urgency)
Help us feel and name different emotional states
Help us feel and name different nervous system states (fight, flight, freeze, etc).
Help us to map our sense of physical and emotional "self"
Everybody has interoceptors. And, with a few exceptions, those interoceptors are sending their afferent signals ("afferent" being a term describing neurons that send information towards the brain and central nervous system) at full volume and normal frequency all hours of the day and night.
But our ability to consciously process that afferent information, and to perceive and interpret it, is another story altogether.
We don't all have strong interoception
In English places, we describe a person who has a refined sense of taste as one with a "strong palate." Someone who can distinguish bird song or complex instrumentation has "a good ear." I married into a family with at least 2 members who are self-proclaimed "super sniffers."
You could think of sensory attunement as "turning up the volume" on a specific sense, but that's not entirely accurate. Because the sensory input is happening (i.e. the volume stays steady), it's our ability to tune into it that is variable.
You see my point. We each have unique relationships with all of our senses. Those relationships may be shaped by genetics, by traumas, or by ongoing, everyday experiences, use, and attention.
That latter point, the "ongoing, everyday experiences, use, and attention" speaks to a broader concept called neuroplasticity — the idea that the brain and nervous system can (and will) form and reorganize synaptic connections, especially in response to learning or to new stimulus. It's the "nurture" side of the "nature versus nurture" conundrum, and it's beautiful because it means that, genetics and trauma aside, each of us has an opportunity to improve our interoception with exposure, practice, and attention.
Measuring Interoception
How do you even know where you land in terms of "low interoception" versus "high interoception?" You might think of this as a scale of competency when it comes to perceiving and interpreting interoceptive input, do you have a sense of where you would fall?
The good news is that neuroscientists and researchers have devised a method for measuring interoception. These folks are typically interested in understanding interoceptive competency as part of our larger ecosystem of health, and their research revolves around two sets of questions:
To what degree can humans actually perceive and interpret interoceptive inputs? How can that perception be measured and compared across individuals?
How does an individual's interoceptive "competence" impact their life? Are other health outcomes correlated to interoception?
Enter: the Heartbeat Tracking Task (or "HTT")
The most common approach that researchers use to measure and assess interoceptive "competency" is through the "Heartbeat Tracking Task" (HTT), also called the "Heartbeat Counting Task" (HCT). Both terms describe a cardiac interoceptive test designed to measure the accuracy of someone's felt sense of their heartbeat.
In a typical use of HTT in a research setting, participants are asked to count their heartbeats without physically measuring their heartbeat over a series of intervals (typically between 3 and 6 time intervals in the range of ∼25 to 100 s). The difference between an objective measurement and the participants’ estimate is taken as a measure of interoceptive sensitivity.
There are multiple methods for HTT, each of them providing a measure of interoception. Rather than regaling you with research-centric methods (which involve a decent bit of math and less than intuitive interpretations) I'll share a more pedestrian, user-friendly version of the HTT (adapted from Til Luchau's Advanced Myofascial Techniqes lecture on Body Sense).
The Heartbeat Tracking Task (simplified)
Find a supported seat, meaning a seat where your spine is supported by your pelvis (rather than a chair back). If you’re comfortable sitting on the floor, great! If you are more comfortable sitting in a chair, just scoot your pelvis forward. If in a chair, I’d recommend sitting with your feet on the floor.
Spend 1 minute breathing and simply noticing your body. For some this may be a familiar exercise. For others it may be torture. This is essentially step 1 to opening up a line of communication with your interoceptors. Notice what is. It’s okay if there’s nothing to notice yet, just follow the rhythm of your breath.
Set a timer for 15 seconds. Once the timer starts, begin to count the number of heartbeats that you can sense from the inside out. That means without using your hands anywhere on your body to check your pulse. Just notice what you can notice when sitting quietly and sensing your heart beating from within.
When 15 seconds is up, write down the number of heartbeats that you could sense from the inside out - we are going to call this your ‘interoceptive pulse,’ the pulse that you took through interoception alone.
Next, reset your 15 second timer. Once the time starts you will retake your pulse, this time using your fingers at the wrist or the neck to sense each heartbeat. Count the number of heartbeats you can sense through this more standard procedure.
When 15 seconds is up, write down the number of heartbeats that you could sense with the help of your fingers - we are going to call this your ‘tactile pulse,’ the pulse that you took with the help of your sense of touch.
Finally, calculate the difference between the interoceptive pulse (IP) and tactile pulse (TP).
Generally speaking, it’s more common to have a lower IP than a TP, so you could subtract IP from TP to get the difference.
Tactile Pulse (TP) minus Interoceptive Pulse (IP) = (#)
If the difference ("#") is negative, that means you sensed more heartbeats interoceptively than you did taking your pulse with your sense of touch. Not a problem! Just take the true value of the difference between these numbers.
Here's a chart to help you (loosely) interpret your results:
Based on the HTT, the higher the numerical difference between your interoceptive pulse (IP) and your tactile pulse (TP), the lower you rank in terms of interoceptive competency.
If this is you, please don't fret! Though this test attempts to quantify interoceptive awareness, it (like many scientific models) is overly-simplistic and comes with many flaws. Even if your results are an accurate representation of low interoceptive awareness on your part, it's important to remember that interoception, like every other sense, can be something you are hyper-attuned to or relatively ignorant of. Many of the known factors that contribute to diminished interoceptive awareness are pervasive and largely beyond our control (stress, overwhelm, aging, and injury, to name a few), so there is no character comment to be gleaned from low interoceptive awareness.
That being said, we do know that we can affect our interoceptive competency with practice and attention (remember, neuroplasticity!). And, especially for folks who score lower on the Heartbeat Tracking Task, there aren't many good reasons not to invest some time and energy towards building interoceptive awareness.
Why interoceptive competency matters
Thanks to the HTT, researchers have been able to correlate a number of conditions with a diminished interoceptive competency. I've categorized a list of correlated conditions (as presented by one of my teachers) below.
It's important to remember that association (i.e. correlation) is not the same as causation. There are a variety of causes of diminished interoception, and those underlying causes might play a significant role in these correlative relationships. Because they do show up together with statistically significant frequency, it's worth considering how diminished interoception might play a role in these conditions, and vice versa.
Physical Conditions Associated with Low Interoceptive Competency*
Over-use injuries and conditions
Athletes are a great example of this dynamic. It's not a stretch to imagine that competitive athletes typically don't have strong interoceptive competency (this was me for many years!). In fact, intensive training typically pushes this population to override signals from their interoceptive sense so that feelings like pain or fatigue don't get in the way of performance. That diminished felt-body sense, along with repetitive (and often aggressive) bodily exertion, put this community at heightened risk for over-use injuries and conditions.
Compromised ergonomics and body mechanics
Consider a desk worker who spends 6+ hours per day seated, with their focus dedicated to a single place (usually a screen). This example presents some parallels with the competitive athletes above. In the case of the desk worker, the act of maintaining a full-time seat is a feat that typically involves overriding interoceptive signals that might encourage them to wiggle, stretch, snack, go for a walk, or lay down to rest. What's more, this population is typically living in their prefrontal cortex (aka their "thinking" brain), so the synaptic connections that relay interoceptive signals to the "feeling" brain are already muted. Much like the competitive athlete, the ample hours spent seated can lead to postural habits that create pain and discomfort, but a lack of interoceptive awareness can make it difficult to feel those postural habits in their body. Since most of us don't typically have a full length mirror at our disposal 24/7, a lack of felt sense about our postural habits makes it very difficult to change them.
*Because these two cases show up often in my Rolfing and yoga teaching practice, I wanted to elaborate on them. I have less experience with the conditions below.
Trauma-Related Conditions Associated with Low Interoceptive Competency
PTSD
Dissociation
Other symptoms of unresolved trauma
Trauma and the felt-body sense share a deep connection that is not linear, and it would be overly simplistic to assert a directional relationship. I will likely dive deeper on this relationship in future blog posts, but what I'll share for now is that many trauma therapies train interoceptive attunement, asserting that improving interoceptive competency provides greater resourcing for healing unresolved trauma.
Developmental Conditions Associated with Low Interoceptive Competency
Sensory integration and sensory processing disorders
Learning disabilities
Autism spectrum disorder
Mental Health Conditions Associated with Low Interoceptive Competency
Difficulty describing emotions
Narrower emotional range
Mood disorders
Body dysmorphic disorder
Eating disorders
SOURCE: Til Luchau's "Working with Proprioception" course
Rolfing® and yoga can help build interoceptive competency
Interoception and the felt-body sense are foundational for anyone looking to build self-awareness, set healthy boundaries, engage with the present moment, and prioritize self-care. That's why one of my priorities in both my Rolfing practice and my yoga teaching practice is to help people develop a more robust and refined inner felt-sense.
A primary avenue (and often-missed opportunity) for making a real impact with bodywork and movement involves attuning to interoceptive input, practicing the art of listening to the body from the inside out, as well as naming and describing the experiences that arise from within.
This is where neuroplasticity becomes our ally. Investing in bodywork or mindful movement practices that help to nurture the synaptic connections that attune us to our felt-body sense is the equivalent of opening up the channels of conscious communication with our interoceptors. The nature of neuroplasticity means we must approach this as a practice — taking small but frequent steps towards turning up the volume on interoceptive inputs so that we may experience the broadest expression of our embodied lives, and resource ourselves towards healthy (and happy!) habits and practices.
If you're based in Portland, Oregon and would like to experience this work in action, you can book a Rolfing session with me or attend one of my local yoga classes. For those based elsewhere (or who want to explore this work from the comfort of your own home) I invited you to peruse my YouTube channel where I publish movement tutorials and self-myofascial release tutorials that help build interoceptive competency.
Practice interoception in everyday life
You have opportunities to invest in building your interoceptive competency every day. It takes practice, but every time that you bring awareness to your felt-body sense, you are strengthening the synapses that help your brain tune into your interoceptive neurons, enlivening your physical experience of your body and your life.
Depending on where you fall on the scale, you may require a different sort of exercise to help you build awareness.
Those with low interoceptive competency will benefit from practices that offer somewhat dramatic shifts in interoceptive input. One example of a practice for folks who are starting with low interoceptive competency might be alternating between hot and cold water while showering. How does your body feel when you're under hot water? How does it feel when you're under cold water? What sort of sensations do you notice when you go from one to the other? When you stop alternating and find your way to a comfortable temperature, what do you notice inside of your experience?
Folks with more mid-level interoceptive competency might benefit from palpation or movement-induced shifts in interoceptive input. I offer quite a bit of this type of interoceptive practice when I teach yoga, and have recorded tutorials that offer opportunities for tuning into the inner felt-sense of the body based on mindfulness and practices:
This guided breathing practice offers 20-minutes worth of interoceptive attunement through breath:
The felt effects before and after this hamstring stretch are dramatic enough that they can help fuel interoceptive awareness:
Self-myofascial release (aka self massage) can offer interoceptive benefits similar to those you might receive from hands-on bodywork:
I'm here if you have any questions! Happy practicing.