What can we learn about pain from mind-blowing illusions?

Our guest here is Oscar Hutton, a neuroscientist and doctoral researcher at Loughborough University. Oscar’s research interests include body perception and persistent pain, and he is investigating how sensory illusions can provide insights into our perceptual experiences. We appreciated his recent visit to the Noigroup HQ in Adelaide, Australia, and enjoyed recording a video on his research topic and experiencing first-hand his insightful Mirror Box demonstration. Please enjoy his writing here and the video recording from the day. Thanks Oscar!

Think about a time you’ve had a minor injury and how it felt. It might seem intuitive that pain is a reliable indicator of the amount of damage to your body, but this idea does not stack up against the evidence (1,2).

Our painful experiences are influenced by the way that we understand pain and the meaning that we think sensations hold (3). Therefore, gaining an insight into the complex relationship between the physical body, the brain’s interpretation of the body, and our experiences of the body can be really valuable – especially for those living with persistent pain.

It is important to acknowledge that we are not merely our brains; it is we who experience sensations. However, given the brain’s significant role in processing and combining sensory information, knowledge, and past experiences, I will refer explicitly to the brain’s involvement in these processes for clarity.

Tackling this in a clinical conversation can be challenging. Explaining pain is difficult in itself, especially when a patient’s previous experiences and understanding do not align with the information presented.

We have been developing an approach that creates a first-person experiential way of having this conversation, breaking down the barriers of pre-conceived ideas by, quite frankly, blowing them wide open. Our approach uses easily reproduced sensory illusions alongside a simple and accessible narrative about body perception and pain as a protective perception(4).

What does your body feel like today? How do you know?

Our brains are always being bombarded with information: both internal signals (for example, from the heart and gut), and external signals (such as sounds and sights). The brain has to filter this information, depending on the context, so that it can bring important things to our attention and deal with less important things in the background.

Our brains continuously combine information from the senses and try to form reasonable conclusions about the body (5–7). The brain then produces relevant sensory experiences, guiding us to take appropriate actions for our well-being. Take the example of hunger: based on available signals and information from the body, your brain might conclude that you need to obtain energy and nutrients, so it can bring this to your attention in the form of hunger. However, on another occasion, your body might be in a similar physiological state – needing energy and nutrients – but because you are being chased by a bear, you probably won’t feel hungry! This is an extreme example, of course, except for those frequently chased by bears, but the point of the story is that your brain is constantly deciding which information to bring to your attention.

It’s very important for us to know when we’re in danger, so the brain alerts us to instances of potential danger using a variety of different sensations, including pain. We can feel pain when our brain concludes that we need to do something differently in response to our body’s signals. For example, a hot stove may feel painful before it has physically burnt us so that we move away from it and don’t allow it to injure us. What this means is that there is a protective buffer between feeling pain and being injured, so we sometimes feel pain when we haven’t been injured. Many of us can relate to the example of stubbing a toe, feeling so much pain that we think it must be broken, but looking down and seeing that it is, in fact, fine. In other situations, we may continue to feel pain when an injury has physically healed, or feel a lot of pain when an injury is small (and vice versa) – see https://www.noigroup.com/noijam/a-tale-of-two-nails/ for two intriguing examples involving nails, if you’re up for that…

Where do sensory illusions come into this?

We said that the brain tries to come to the most sensible conclusion based on the information it receives from the body, but sometimes these conclusions can be wide of the mark. We use sensory illusions to highlight just how much the brain can come to inaccurate conclusions.

For example, just using a standard mirror, we can create the feeling that a person has an additional, invisible finger (8). It feels incredibly real and can be achieved almost instantaneously. We can use this (and other fun illusions) to allow a patient, or any member of their support network, to get a first-hand (painless) experience of their own brain coming to an inaccurate conclusion about their body. They can feel for all the world like they have an extra finger when, demonstrably, they do not. It opens up the opportunity for having conversations about the nature of bodily sensations, including pain, and how our sensations cannot truly inform us about the body (9,10).

Changing what pain means

The point to emphasise is that pain means that your brain has concluded that you’re in potential danger. The pain is certainly real, but the cause of it might not be what it seems.

In our work at Loughborough University, we use body illusions and other sensory experiences to help people understand how perceptions of the world and our bodies are formed in the brain. We have developed an interactive workshop, in which we demonstrate some inaccurate conclusions that the brain can come to, leading to experiences that don’t entirely match what is happening.

The reframing conversation for patients and families

Using illusions like the one described above (which is called the Anne Boleyn Illusion (8)) helps us to explain that:

1. Pain doesn’t mean damage: Your perception of your body, including pain sensations, while very real and very convincing, is not an accurate reflection of the physical state of your body.
2. Change is possible: The brain continuously puts information from our senses together with our current knowledge to form conclusions. This means that changing the way we think about pain can change the conclusions the brain comes to – moving away from a conclusion of damage.

Creating this window of understanding is not just useful for patients. When engaging with people living with persistent pain, some have mentioned that their support networks (for example, family members and friends) can struggle to understand how they feel. In some instances, people in pain are not believed because their issues aren’t visible, which can lead to additional difficulties. Hence, we suggest that our workshop could be a good way to help support networks to understand that people can feel immense pain, even when their body looks healthy. Unexpected illusory body experiences (alongside appropriate explanations)may help support networks to empathise with people living with persistent pain and reduce the overall burden of their pain.

Body perception beliefs

To help us understand more about how we can change understanding about perception and pain, we first need to understand what people – with and without pain – think about the links between their brain and their body, and what makes up their body perception. To do this, we have developed an online survey, which takes an average of 10-15 minutes to complete. We would be incredibly grateful if you could complete the survey and share it with your networks. The more data we get, the more we can develop our understanding.

You can find the survey here.

And our video here.

– Oscar Hutton
Neuroscientist and doctoral researcher
Loughborough University London

Further reading
What illusions can teach us about pain Pain and Perception: A closer look at why we hurt (Harvie & Moseley, 2021)

Reference list:

1. Babińska A, Wawrzynek W, Czech E, Skupiński J, Szczygieł J, Łabuz-Roszak B. No association between MRI changes in the lumbar spine and intensity of pain, quality of life, depressive and anxiety symptoms in patients with low back pain. NeurolNeurochirur Pol. 2019;53(1):74–82. Link here
2. Brinjikji W, Luetmer PH, Comstock B, Bresnahan BW, Chen LE, Deyo RA, et al. Systematic literature review of imaging features of spinal degeneration in asymptomatic populations. AJNR Am J Neuroradiol. 2015; 36(4):811–6. Link here 
3. Caneiro JP, Bunzli S, O’Sullivan P. Beliefs about the body and pain: the critical role in musculoskeletal pain management. Braz J Phys Ther. 2021; 25(1):17–29. Link here
4. Moseley L, Butler D. The Explain Pain Handbook: Protectometer. Noigroup Publications (2015)
5. Eckert AL, Pabst K, Endres DM. A Bayesian model for chronic pain. Frontiers in Pain Research. 2022; 3. Link here 
6. Boyce WP, Lindsay A, Zgonnikov A, Rañó I, Wong-Lin KF. Optimality and Limitations of Audio-Visual Integration for Cognitive Systems. Front Robot AI. 2020; 7(94): 1-17. Link here 
7. Perera ATM, Newport R, McKenzie KJ. Changing hands: persistent alterations to body image following brief exposure to multisensory distortions. Exp Brain Res. 2017;235(6):1809-1821. Link here
8. Newport R, Wong DY, Howard EM, Silver E. The Anne Boleyn Illusion is a Six-Fingered Salute to Sensory Remapping. Perception. 2016; 7(5):1–4. Link here 
9. Tanaka S, Nishigami T, Ohishi K, Nishikawa K, Wand BM, Stanton TR, et al. “But it feels swollen!”: the frequency and clinical characteristics of people with knee osteoarthritis who report subjective knee swelling in the absence of objective swelling. Pain Rep. 2021; 6(4): 1-8. Link here 
10. Stanton TR, Moseley GL, Wong AYL, Kawchuk GN. Feeling stiffness in the back: A protective perceptual inference in chronic back pain. Sci Rep. 2017; 7(1): 1-12. Link here