When a person with Anorexia Nervosa looks in the mirror, they often report seeing someone who is very overweight rather than the thin body that they actually have.
In the classic detector model of sensory processing, it can be hard to understand how the person can see something that is not reality.
Predictive processing* provides another explanation. that the person is seeing the brains prior model or prediction that they will see, and due to the stress of the condition , they are ‘stuck’ on the predicted model unable to see the reality. A persons predictions are built up from prior experiences and also information from interoception ie feeling fat.
If you are interested in reading an article, this one is good:
“ Our findings suggest that individuals with AN prioritize interoceptive metacognitive processes (i.e., confidence in their own perceived sensations rather than their actual perceptions), disregarding bottom-up bodily inputs in favour of their prior altered top-down beliefs. Moreover, even if the rehabilitative program partially mitigated these alterations, the pathological condition impaired the patients' ability to coherently update their prior erroneous expectations with real-time multisensory bottom-up bodily information, possibly locking the patients in the experience of a distorted prior top-down belief. These results suggest new therapeutic perspectives and introduce the framework of regenerative virtual therapy (RVT), which aims at utilizing technology-based somatic modification techniques to restructure the maladaptive priors underlying a pathological condition.”
*What is predictive processing:
Predictive Processing is a computational theory of brain functioning where the brain continuously works to minimise error between existing model-based predictions and incoming information (May et al 2021). The theory asserts that the brain generates prior models or predictions of sensory input at multiple levels, generating expectations or inferences regarding future input. This function serves to minimise uncertainties and maximise efficiencies (Wilkinson et al, 2017). Predictive processing as a theory also helps to explain the large number of descending connections in the brain (Walsh et al 2020). In the instances where unpredicted or unexpected sensory input is detected (referred to as a prediction error) this information may pass through these multiple layer and then can update the prior model.
Predictive Processing has been described as “A leading theoretical framework for Sensory Processing” (Tabas et al 2021) and has a lot of ‘explanatory power’ for mental health and sensory processing clinical areas.
Predictive Processing Course:
References:
Di Lernia, D., Serino, S., Tuena, C., Cacciatore, C., Polli, N., & Riva, G. (2023). Mental health meets computational neuroscience: A predictive Bayesian account of the relationship between interoception and multisensory bodily illusions in anorexia nervosa. International Journal of Clinical and Health Psychology, 23(4), 100383. https://doi.org/10.1016/j.ijchp.2023.100383
https://www.sciencedirect.com/science/article/pii/S1697260023000194