## 2. Perceptual Structure Our central claim in this paper is that one medium specificity of virtual reality is that it is capable of changing certain structural features of perception. In this section we will provide some detail as to what invariant structural features are. In the next, we will suggest that these structural features can be altered by certain technological interventions. In Section 4, we will argue that Bordini describes invariant structural features as follows: > by attending to the objects of the experience, we can introspectively discern certain invariant structural features, such as the visual field or its boundaries, which remain constant as objects and properties change. Such structural features are modality-specific and are responsible for how we experience things within that modality. Consequently, they are not properties of what we experience but of the experience itself (2023, p. 271) The visual spatial field is the most obvious example of a structural feature. It seems right to say that visual experience is 'field-like' in that it presents objects as occupying positions within a bounded region of space, in a way that olfaction or audition do not. Richardson’s work on the spatial field brings out several aspects of this type of structural feature. First, it remains constant as the objects and properties represented change: your vision will seem field-like, wherever you look and whatever you look at. Indeed, your visual field persists when you close your eyes, or open them in a pitch black room.  Second, it shapes our visual experience: #### "The feature also deserves to be called 'structural' because what it contributes to the qualitative character of visual experience, in general, is something quite distinctive: it 'structures', or 'organises' it. It imposes a certain form on visual experience” (p. 13) Third, our awareness of the visual spatial field in our visual experience is quite different from our visual awareness of the objects we see: #### "These features structure our perceptual experience of the things we are aware of. Vision's having its spatial field, on this view, is not a matter of our being aware of another object, or property of an object, in addition to, say, the lemon and the table and their properties. So there is no appropriate additional object or property of an object to attend to, when reflecting upon these structural features of perceptual experience." (p. 493) This view allows Richardson to maintain that when we introspect, we are still primarily aware of the objects in the world, not features of our experience. Furthermore, Richardson does not consider her account to be a version of qualia theory because she doesn't treat the visual field as an additional sensational property or a detachable quale. Instead, she argues that it is an intrinsic, organising feature of visual experience: "Similarly, the structural feature of visual experience involved in seeing empty space is intrinsic to the qualitative character of visual experience generally, rather than some positive quality that each visual experience has and could lack. It is a feature of all visual experience, and not just visual experience of empty space" (p. 12). By characterising the visual field as a structural feature that organises experience rather than an additional content or property, Richardson distinguishes her account from qualia theories of perceptual experience. ## 3. Perceptual Restructuring We now want to make a further suggestion: it is possible for at least some structural features of perception to be altered via technological means. In this section, we will give some examples. In the next, we will show that VR Hardware is very well-suited to produce similar alterations.  Consider inverting lenses and prism glasses. These optical devices alter the spatial orientation of the visual field: inverting lenses flip it vertically, making the world appear upside down, while prism glasses shift it horizontally or vertically. This alteration can be understood as modifying the structural properties of vision in several ways that align with Richardson's characterization. First, the inversion or displacement is not a matter of perceiving new objects; the content of perception remains unchanged while its spatial organisation is transformed. Second, this reorganisation remains constant throughout the use of the devices, persisting as an invariant feature of visual experience. Finally, this technology the structure of visual experience by disrupting the usual spatial relationships that organise our perception. Just as Richardson describes the visual field as imposing "a certain form on visual experience" (REF) these devices impose a new form, one that is an inverse of the normal one. Cochlear implants offer another instance of perceptual restructuring, this time in the auditory domain. These electronic devices provide a sense of sound to individuals with severe hearing loss by directly stimulating the auditory nerve, bypassing damaged hair cells in the cochlea. They alter the structural properties of auditory perception in ways that align with Richardson's characterization of structural features. First, the change is not a matter of hearing new auditory objects, but rather a reorganisation of how sound waves are processed. In ordinary hearing, the cochlea's tonotopic organisation allows for continuous, high-resolution frequency discrimination. Cochlear implants, however, divide the frequency spectrum into discrete bands, typically between 12 to 22, each stimulating a different region of the auditory nerve. This discretization of frequency perception remains constant during the use of the implant, satisfying the second feature of structural properties. Lastly, this alteration reshapes the structure of auditory experience. The limited number of frequency bands results in a reduced spectral resolution compared to natural hearing, affecting the perception of pitch and timbre. This change in frequency structure modifies how auditory information is organised in perception, altering the form of auditory experience without introducing new auditory objects or properties. Finally, visual field expanding devices for hemianopia provide a third example of perceptual restructuring, one that directly relates to Richardson's discussion. These devices use optical elements like mirrors or prisms to redirect light from areas of peripheral vision loss into intact areas of the visual field. For individuals with hemianopia, who have lost half of their visual field due to conditions such as stroke, these devices effectively alter the structural property of the size and boundaries of the visual field. This alteration aligns with Richardson's characterization of structural features in several ways. First, it doesn't introduce new objects of perception but changes how existing visual information is organised. Second, the expansion of the visual field remains constant during the use of the device. Third, it modifies the structure of visual experience by changing the spatial layout of visual information. Notably, this example directly affects the visual spatial field, a key structural feature in Richardson's account. By allowing users to perceive objects in previously blind regions, these devices demonstrate that even fundamental structural properties of perception, such as the extent and limits of the visual field, can be modified through technological intervention.