What do ‘vestibular’, ‘proprioception’ and ‘interoception’ mean?
In primary school we all learned about the five senses: sight, hearing, touch, smell and taste. You might also know them as the body’s sensory systems, where they get fancier names: visual, auditory, tactile, olfactory and gustatory (STAR Institute, 2020). However, there are some important senses that this basic system doesn’t cover. In fact, our bodies have eight senses, which also include our vestibular system, proprioception and interoception.
Vestibular
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Our vestibular system helps us balance and informs us where we are in space. This means that it tells us when we’re moving, how fast we’re going, and the direction we’re moving in. Our vestibular system is located in the inner ear, where a team of three canals detect movement and deliver the signals to our brain. It works automatically and subconsciously, so most people aren’t even aware of the vestibular system working (STAR Institute, 2020; Vance, 2019).
To give a practical example, one of the most common problems our vestibular system can cause is motion sickness. Motion sickness typically occurs when our vestibular system is receiving information that clashes with what we’re seeing with our eyes (Better Health Channel, 2014). In a car, your vestibular system knows that your body isn’t moving, but your eyes can see the landscape flashing by. The mixed messages confuse the brain and lead to dizziness and nausea.
Proprioception
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Proprioception is also referred to as kinaesthesia (Taylor, 2009) and refers to how we perceive our bodies in relation to the world around us. Like the vestibular sense, it relates to movement, but it’s far more physical. Proprioception affects the way we move and interact with objects.
It’s a complex sense that involves information from our muscles, skin, joints and central nervous system. Proprioception is what enables us to understand our limb movements, as well as feeling things such as force, heaviness and stiffness. Have you ever picked up a box and quickly realised it’s far heavier than you expected? That’s your proprioception at work! Combined with our other senses, proprioception tells us where external objects are in relation to us (Taylor, 2009; Vance, 2019).
What does proprioception look like in practice? Someone with a high level of proprioception will rarely fall over or knock things off benches by accident. They might be described as graceful or athletic, and are the sort of person who never has food stains on their shirt. Conversely, a person with low proprioception is likely to be considered clumsy, and probably bumps into people or furniture as they walk. They might exert too much force - I, for example, have a track record of breaking doorknobs, because I pull or twist them too hard. People with low proprioception might have difficulty with tasks such as climbing or typing, which require awareness of your body in relation to an object. In extreme cases, someone with a severely inhibited proprioceptive system will need to be looking at their limbs and consciously plan their movement in order to successfully complete a simple task (Vance, 2019).
Interoception
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Interoception is a broad sense which includes all the signals your brain receives from your body’s internal organs - that’s your heart, lungs, gut, bladder, kidneys and more. Interoception is our body’s way of telling us what’s happening internally. Much of this information is processed at a subconscious level, such as the signals that control your blood pressure. The other signals are available to our conscious minds (some of the time). Things like hunger, pain or a full bladder are the most prominent signals we receive, but things like muscle tension and heart rate are also things we can choose to tune into (Robson, 2021; Vance, 2019).
How quickly are you breathing right now? Breathe in for 4, then out for 4. Chances are you are now very aware of the speed of your breathing (sorry). This is an example of our subconscious interoceptive processes becoming conscious, because we choose to think about it. If your interoception functions normally, this should be pretty easy to do. However, people who a particularly high or low level of interoception might experience these sensations differently.
People with sensitive interoception may be constantly aware of what’s going on in their body. They may have a low pain tolerance, be unable to cope with temperature fluctuations, struggle immensely when they’re tired or even be overwhelmed by a mild illness like a cold or a headache. As a result, they are forced to focus on meeting their body’s needs in order to function. On the other hand, someone with a low level of interoception might miss important cues from their body, such as thirst or hunger. They might forget to go to the toilet until it’s urgent, or overeat because they don’t realise they’re full. They are also far less aware of pain - they have random bruises show up and not remember what caused them, and in severe cases, go days before they notice a serious injury. Both extremes can be harmful to the individual. (Vance, 2019).
The vestibular system, proprioception and interoception are all important to how we process what’s occurring in our body and the world around us. Unfortunately, there are many factors that can impact these systems: illnesses, disabilities and even physical injuries can all skew our senses. It can be hard to express when something isn’t working right without the accurate vocabulary. Hopefully your understanding of these sensory systems can help you to advocate for yourself and your loved ones!
References
STAR Institute. (2020, May). Your 8 Senses. https://sensoryhealth.org/basic/your-8-senses
Vance, T. (2019, March 19). The Other 3 Senses You Never Knew Existed… But You Should! NeuroClastic. https://neuroclastic.com/the-other-3-senses-you-never-knew-existed-but-you-should/
Better Health Channel. (2014, November 30). Motion sickness. https://www.betterhealth.vic.gov.au/health/healthyliving/motion-sickness
Taylor, J. L. (2009). Proprioception. In Squire, L. R. (Ed.), Encyclopedia of Neuroscience (pp. 1143-1149). Academic Press. https://doi.org/10.1016/B978-008045046-9.01907-0
Robson, D. (2021, August 15). Interoception: the hidden sense that shapes wellbeing. The Guardian. https://www.theguardian.com/science/2021/aug/15/the-hidden-sense-shaping-your-wellbeing-interoception
