The sense of bodily ownership is perhaps the most important aspect to bodily experience. It gives rise to the body's privilege status as the only object we experience as our own, experienced as subject. But despite how basic this sense is, describing what it is and how it works has been anything but straight-forward, The best explanation for the sense of bodily ownership is arguably the Spatial Hypothesis. It claims that the sense of bodily ownership derives from the spatial representation of the body. Although isupport this hypothesis, I argue that past attempts at grounding it risk resulting in a Cartesian circle. I propose a solution distinguishing between capacity and content.
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1. Sense ofBodily Ownership and the Spatial Hypothesis
Compared to all other objects of experience, the body has its unique status because of the privileged perspective we have on it. We view the body 'from the inside'; recently, reference to the body's privileged status has been made even without the scare quotes. One aspect to this internal viewpoint is the sense of bodily ownership: we experience our body as our own. Is this sense of ownershipover and above the sense of bodily awareness? Is it a product of it? Does the sense of bodily ownership have its own phenomenology, its own raw feel?
I will leave many of these questions aside. Instead of addressing these arguments, I will concentrate on the discussion that seeks to ground the sense of ownership in bodily awareness. More particularly, I'll concentrate on the research that seeks to ground the sense of ownership in the spatial representation of the body, 'ffiis means, I assume that the sense of ownership is dependent on bodily awareness, that the sense of ownership has a positive status, that it does have its own, albeit implicit, phenomenology.
Before I present the debates concerning how to ground the sense of ownership, I would like to explain what is meant by an implicit phenomenology of bodily ownership. At this moment, while I'm typing, I'm not explicitly aware that my hands are my hands. Instead, I'm aware of my thoughts, how they might let themselves be expressed in the English language and, in a less explicit sense, the location of the proper keys on the keyboard. Implicitly, I'm aware of the distance between my fingers, the temperature of the room and its air pressure, and a whole host of other data concerning my body and its environment. I don't need to be explicitly aware of bodily ownership in this moment because nothing requires that I make use of it. As analogy, nothing requires that I make use of the sense of ambient temperature, 'ffiis is because it is a comfortable eighteen degrees Celsius in my office. But should a massive, purple cloud be ushered in by eastern winds, block the sun and pour rain upon my town, I'd suddenly become aware of the temperature and, as a result, I might turn off my fan. In the same vein, if I had a lesion in the right hemisphere of my brain and suffered from asomatognosia, I'd be aware that my right arm belonged to me, while my left arm did not. 'ffius, it is in this sense that bodily ownership is implicit: the sense of ownership becomes content for conscious only when a deficit is present.1
I would like now to give a quick overview of the differing accounts that ground the sense of ownership. I'll end with the Spatial Hypothesis, followed by reasons for why it is arguably the best explanation. We begin with the question, Does bodily sensation give rise to the sense of ownership? Inother words, when I feel a pain in my right hand, do I also sense that the pain is located in a body part that belongs to me? If we dismiss this question, or if we claim bodily sensations do not give rise to the sense of ownership, then we leave the discussion. So for present purposes, let's assume that bodily sensation, such as pain, gives rise to the sense of ownership, 'ffiis assumption requires justification, however. We could argue that the sense of ownership is grounded in a privileged, inward perception-different than introspection—that has special access to the pain in my right hand, but then we'd need to justify the existence of a wholly different form of perception. Alternatively, we could fix the mode of perception and vary the content of perception, 'ffiis would mean that the mode of perception that has access to bodily sensations is the exact same perception used in everyday perception of objects, The difference between perceiving bodily sensations and external objects is merely the perceptual content, The question arises now, What makes this content sufficient for grounding the sense of ownership? Is the sense of ownership grounded by the descriptive component to the content, e.g. the stabbing sensation of the pain? Or could it be the spatial component of the content, e.g. the assignment of the sensation to my hand?
I'll focus solely on this latter approach to understanding the relationship between bodily awareness and the sense of bodily ownership, 'ffiis approach, called the Spatial Hypothesis, claims that the spatial component of the content of perception is the source of the sense of bodily ownership, i.e. the sense of bodily ownership is derived from the spatial representation of the body. Inother words, imagine you have a sense of pain in your right hand, The Spatial Hypothesis claims that you know that this pain is in your right hand because along with the descriptive component of this sensation, such as a stabbing-sort of pain, there is information about the location of the sensation, and this information falls within the boundaries of the body.
There are three reasons for why the Spatial Hypothesis is a good candidate. First, it is supported by the measures of embodiment. Second, spatial representations of the body correspond to the body schema, opposed to the body image. Lastly, the Spatial Hypothesis integrates multimodal representations of the body, opposed to uni-modal representations. All three reasons will be illustrated shortly, but I'm presenting these reasons merely to motivate the reader, not to argue for the hypothesis.
Measures of Embodiment: The sense of embodiment occurs when something is being processed as a body part; embodiment occurs when this process takes place, The sense of embodiment in not binary: it is not the case that either something is processed as a body part or something is not. There are therefore many different categories of embodiment, aptly shown by the three measures of embodiment: spatial, motor, and affective. Not all are relevant for a sense of ownership, however, for only those measures of embodiment that instantiate what is called selfspecific embodiment can ground the sense of ownership.
Self-specific embodiment differs from neutral embodiment. Self-specific refers to those measures of embodiment that can only apply to one's own body, while neutral embodiment can apply to experiences concerning other people's bodies. For example, affective measures of embodiment are neutral; they measure reactions to a hazardous situation, such as a threatening hammer. Studies have shown that this kind of embodiment occurs when someone else is being threatened, The sense of ownership can only be grounded in measures of embodiment that are not shared by both oneself and others, as it doesn't make any sense to talk of a sense of ownershipof someone else's body part, There is one spatial measure of embodiment that is self-specific, however.
In order to explicate this self-specific measure of embodiment, some further terminology needs to be introduced. All spatial measures are divided into three frames of reference: the bodily frame, the external frame, and the peripersonal frame, and those that fall into the bodily frame necessarily incur the sense of self-specific embodiment.
The bodily frame instantiates embodiment when something is processed by the representation of the body in space as defined by its boundaries and segmentation into body parts —an example would be a prosthetic limb, The objects processed by the bodily frame cannot be neutral; they are guaranteed to be self-specific. Because the Spatial Hypothesis claims that the sense of ownership is grounded in the spatial representation of the body, it is supported by the results found by the measures of embodiment, which hold that only those measures that are processed within the bodily frame can be self-specific. To put that another way, the spatial representation is implied by the bodily frame, the bodily frame instantiates processes that are guaranteed to be self-specific, and only processes guaranteed to be self-specific can ground the sense of ownership.
The Body Schema: We can talk about the body image, or we can talk about the body schema, The body image is long-term configuration of the body, including more general and psychological aspects, such as how we feel about our body. One's body image is constituted in part by the depositional stance one takes towards one's body. For example, if I believed I'd needed to lose weight in order to look good in a bathing suit, then this belief would integrate into my body image, The body schema, however, is constituted by the sensori-motor functions of the body, i.e. the body schema is composed of the data concerning those physiological components of the body necessary for behavior and action, The body schema is essential in explaining how a subject, suffering from pathological cases of disembodiment, reacquires a sense of embodiment and a sense of bodily ownership. When asking which of the two the Spatial Hypothesis corresponds to, it becomes clear that it corresponds to the body schema due to its integration of sensori-motor information, The link between the Spatial Hypothesis, the body schema, and the sense of bodily ownership supports the claim that the sense of bodily ownership is grounded in the spatial representation of the body.
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- John Dorsch (Autor), 2015, Locating the Spatial Hypothesis Outside the Cartesian Circle. The Sense of Bodily Ownership and The Capacity to Differentiate Between Oneself and Not Oneself, München, GRIN Verlag, https://www.grin.com/document/412284