If you’ve ever looked in the mirror and felt like the person staring back at you wasn’t quite ‘you’, you’re not alone. People with eating disorders (e.g., anorexia nervosa, bulimia nervosa) and body dysmorphic disorder often experience profound disturbances in how they perceive their own bodies – a condition called body image disturbance (BID). At its core, BID involves two major components: cognitive-affective disturbance (negative thoughts and emotions about body shape/weight) and perceptual disturbance (misperception of body shape/weight, typically overestimation). Both eating disorders and body dysmorphic disorders are associated with high mortality rates, which makes understanding and treating BID an imperative.
While therapies like cognitive behavioural therapy (CBT) can help ameliorate the cognitive-affective aspects, targeting the perceptual distortions has been trickier. After all, how do you fix something as fundamental as inaccurately perceiving your own physical self? A novel approach that’s gaining momentum for both understanding and treating BID uses ’embodiment illusions’ – these are experiences where your brain is tricked into temporarily adopting/owning (or “embodying”) an artificial body part or full body that isn’t yours. For example, experiencing stroking on your own (unseen) face whilst observing another person’s face being simultaneously stroked in front of you typically produces the illusion that the other face is your own.
In our recent systematic review, my colleagues and I summarised evidence from 32 studies showing that people with higher BID tend to be more susceptible to embodiment illusions compared to those with lower BID. Why might this be? One proposal is that BID stems from dysfunctional multisensory integration – an inability to properly combine inputs from different senses (e.g., vision, touch, proprioception [i.e., awareness of the position/movement of the body], etc.) into a coherent self-image. For instance, it’s been argued that those with anorexia nervosa seem to over-rely on visual inputs about their desired, thin ideal physique at the expense of contradictory sensory signals (e.g., touching one’s ribs) which would otherwise indicate their body is (already) underweight. As a result of this impaired integration process (and hence, increased susceptibility to embodiment illusions), people with anorexia nervosa may see themselves as ‘large’ despite being underweight.
These embodiment illusion findings align with ‘predictive coding’ models of body perception. Such models posit that our brains rely on a process comparing incoming sensory input about our current appearance with predictive models or “priors” about what our bodies should look like based on past experience. For example, the illusion of inducing ownership over another person’s face (described above) could be seen as replicating a mirror-like experience: because we typically see ourselves touch our face via a mirror whilst simultaneously feeling the tactile input, the brain misperceives the other person’s face, which is being stroked at the same time as one’s own face, as belonging to oneself. In people with BID, being more susceptible to embodiment illusions suggests that, perhaps based upon disturbances in multisensory integration, these distorted priors remain stubborn at the expense of processing real-time sensory signals about our current physical state.
The Allocentric Lock Theory builds on this, suggesting those with eating disorders view their bodies from a detached, observer perspective (“seeing” themselves as overweight) despite being underweight – in essence, being locked into distorted representations of having the wrong body due to issues with integrating current multisensory information (like that from vision and touch showing that the body is underweight). In summary, via these lenses involving predictive coding and allocentric lock theories, our embodiment illusion findings shed increased light on the multisensory integration processes that underlie BID.
Importantly, our review findings are not restricted to the issue of better understanding why BID may occur. Since these illusions temporarily override your brain’s mental image about your body by providing multisensory cues that an artificial body part or another entire body is your own, this can be used to update (and improve) your own body image in the direction of an embodied model’s ‘idealised’ physical characteristics. For example, experiencing embodiment with a healthy-weight model may reduce body size overestimation in individuals with anorexia nervosa.
Indeed and excitingly, we found that across 24 studies, experiencing these illusions tended to improve BID, including perceptual distortions (e.g., reduced body size overestimation) and associated cognitive-affective symptoms (e.g., reduced body dissatisfaction and fear of gaining weight). Importantly, these BID improvements often occurred regardless of the individual’s initial disturbance level. In other words, embodiment illusions may also offer preventative or positive value for subclinical populations, reducing the chances of developing clinically significant eating disorders or body dysmorphic disorders. For those already with such clinical disorders, embodiment seems to reduce symptoms stemming from body shape/weight misperceptions and therefore serve as a much-needed potential adjunct to current therapies (like CBT) to more holistically target BID’s cognitive-affective and perceptual aspects.
While our review revealed limitations and challenges facing researchers (especially measurement inconsistencies across studies), the overall pattern involving medium- to large-sized improvements in BID from pre- to post-embodiment experiences highlights the potential clinical utility of these illusions. Certain aspects made embodiment illusion effects for reducing BID more potent, like targeting high distress areas like the abdomen or embodying idealised physiques of a lower weight than oneself. Utilising these insights from our review, future research may be able to optimise embodiment paradigms for precise intervention in BID populations.
Ultimately, BID can have detrimental effects on an individual’s everyday life, impacting their ability to experience a positive and adaptive body perception. Embodiment illusions suggest a promising avenue for both better understanding the mechanisms underlying BID and potentially improving body shape/weight misestimations that contribute to eating disorder and body dysmorphic symptoms. These findings have implications for prevention in subclinical groups and intervention for those already suffering from distorted self-perceptions. Next time you look in the mirror whilst brushing your teeth or hair, know that the multisensory integration processes occurring within your brain are now being used by BID researchers to open important avenues that may be explored for many years to come.
Target Article
Portingale, J., Krug, I., Liu, H., Kiropoulos, L., & Butler, D. (2024). Your body, my experience: A systematic review of embodiment illusions as a function of and method to improve body image disturbance. Clinical Psychology: Science and Practice. Advance online publication. https://doi.org/10.1037/cps0000223
Discussion Questions
- According to the blog, what are the two major components of body image disturbance (BID)?
- How does the blog explain why people with higher BID tend to be more susceptible to embodiment illusions?
- What theories or models of body perception are discussed in relation to the findings on embodiment illusions and BID?
- Based on the review findings summarised, what potential clinical applications of embodiment illusions are suggested for addressing BID?
About the Authors
Jade Portingale is a PhD candidate in the School of Psychological Sciences at The University of Melbourne, Australia. She can be contacted at jade.portingale@unimelb.edu.au.
Dr. David Butler is a senior lecturer and researcher at The Cairnmillar Institute, Australia. He can be contacted at: david.butler@cairnmillar.edu.au