Manipulating body representations with virtual reality: Clinical implications for anorexia nervosa

ABSTRACT

Anorexia nervosa patients exhibit distorted body-representations. Specifically, they represent their bodies as larger than reality. Given that this distortion likely exacerbates the condition, there is an obligation to further understand and, if possible, rectify it. In pursuit of this, experimental paradigms are needed which manipulate the spatial content of these representations. In this essay, I discuss how virtual reality technology that implements full-body variants of the rubber-hand illusion may prove useful in this regard, and I discuss some issues related to the clinical application of this method.

KEYWORDS:

• Anorexia nervosa
• body-image
• body-schema
• rubber-hand illusion
• treatment
• virtual reality

Acknowledgments

Thanks to Manja Engel for useful feedback.

Disclosure statement

No potential conflict of interest was reported by the author.

Notes

1. Oftentimes participants will take a more active role in the estimation process, drawing or marking out the distance of certain body parts themselves.

2. Considering the assumptions behind such tasks also clarifies the target of interest as the representational rather than the experiential content. Participants need not have any conscious experience of the two images being compared; rather, the process occurs entirely unconsciously. The only thing participants become aware of is the resulting judgment (i.e., ‘the presented body is smaller or larger than my own”).

3. For many, the debate over whether the BSE evidence thus far uncovered is truly indicative of perceptual body-image distortion is still not resolved (Mölbert et al., 2018; Moscone et al., 2017). However, I won’t delve into these issues here. For now, I simply accept the background assumption of the empiricist approach – also held by many AN researchers – that AN patients exhibit perceptual body-image distortion.

4. Interestingly, while the explicit perceptual body-image is thought to represent the surfaces of the body accurately, implicit representations routinely exhibit distorted spatial content (Longo, 2015). That said, this kind of widespread, non-pathological distortion isn’t relevant here.

5. Given that this involves comparison with vision of whole bodies (akin to depictive size estimation), only the dimensions of the explicit perceptual body-image are relevant.

6. The relationship between the experience of self–other comparison and the awareness of body-size information can be understood as a form of inferential dependence (Fulkerson, 2014, p. 86). Though patients don’t directly perceive false bodily dimensions through such experiences, they do become aware of these dimensions in virtue of them (Gadsby, 2017b, p. 605–606). Within the empiricist literature, this is what’s referred to as an explanationist account, whereby delusions arise as an attempt to explain anomalous experiences. Such accounts are in contrast with endorsement accounts, where the content of an anomalous experience is simply endorsed as a belief (Bayne & Pacherie, 2004).

7. The researchers distinguished between three different targets for body-estimate tasks: the experienced body, the physical body, and the virtual body. Relevant to the current discussion are the results of tasks aimed at measuring the experienced body, which the researchers defined as “the body that the participant feels she has at that moment” (p. 2). I won’t delve into the results associated with the other two terms.

8. For example, it’s been shown that age partly determines representation malleability (Serino et al., 2018).

9. This is not to definitively claim that they won’t have an effect. However, there is currently no known explanation for how such traits could affect the sensory mechanisms tasked with updating the spatial content of the perceptual body-image and body-schema.

10. Indeed, during the VR experiment conducted on AN patients, many of them appeared pleasantly surprised by the experience, making statements such as “oh wow, I am so skinny now, this is cool!” (Anouk Keizer, personal communication; see also Keizer et al., 2016, p. 16).

11. Thanks to an anonymous reviewer for pushing me to address this point.

Additional information

Funding

This research was supported by an Australian Government Research Training Program (RTP) Scholarship.

Notes on contributors

Stephen Gadsby

Stephen Gadsby is at Monash University, Sydney, Australia, but the correct city is Melbourne, not Sydney.