# Consensual Illusion: The Mind in Virtual Reality  ## Metadata - Author: [[Vanja Kljajevic ]] - Full Title: Consensual Illusion: The Mind in Virtual Reality - Category: #articles - Summary: insert summary - My notes: - Summary: The text is titled "272540_1_En_Print.indd" by author 0014813. It belongs to the domain readwise.io. - URL: https://readwise.io/reader/document_raw_content/173329335 - Source File: Consensual Illusion –The Mind in Virtual Reality by Vanja Kljajevic.pdf ## LLM Chats ## NotebookLM ## LLM Audio ## Highlights > The notion of extension as an instrument of perception and cognition is certainly not new. For instance, Merleau-Ponty (1958) argued that a stick in the hand of blind man becomes an instrument instead of object of perception, and as such it is an extension of his body. Telescopes and microscopes expand our view of reality so that we can see distant galaxies and observe microorganisms for which we cannot know to exist when we look by the naked eye. Due to these extensions, our senses can reach further. Anthropologists use the concept of extension to refer to improvements or specialization of human mental and physical functions by means of external tools: The computer is an extension of part of the brain, the telephone extends the voice, the wheel extend the legs and feet. Language extends experience in time and space while writing extends language. (Hall 1969,p.3) ([View Highlight](https://read.readwise.io/read/01hxv1k8gkv7zt4y4fnpasx0ry)) > Virtual reality technology is an example of tool that allows us to experience having abilities that surpass those characteristic to human beings, a different sense of corporeality, and more generally a different sense ofself. ([View Highlight](https://read.readwise.io/read/01hxv2d18tk4tsj5m860npwtdk)) > The feeling of disembodi- ment is expected to arise in situations when digital immersion is not accompanied by appropriate bodily and environmental feedback. In fact, the sense of disembodiment is relatively common in virtual environments that use head mounted display-based virtual reality systems, because they rarely display a rendering of the participant’s real body. It has been demonstrated that a presence ofan avatar as participant’s repre- sentation in a virtual environment has beneficial effects on the sense of presence and task performance, and that presence of a self-avatar may affect interaction in shared virtual environments, benefiting cooperative tasks and increasing the level of trust among the collaborators, as well as the sense of presence and perceptual judgments (Pan and Steedman 2017). But as emphasized by Hayles (1999), the point is not in “leaving the body behind”, but in “extending embodied awareness” in ways that would not be possible without the use of specific technology (p. 291). ([View Highlight](https://read.readwise.io/read/01hxv2fvk4pdyq9r7gq7bvw2xz)) > The concept of presencewas introduced by AndréBazin in 1951 in the context offilm experience and in the 1970s it was extended to communication phenomena mediated by technology (Lombard and Jones 2015). ([View Highlight](https://read.readwise.io/read/01hxv2jyvcqh27my2y4sgjezda)) > h ([View Highlight](https://read.readwise.io/read/01hxv2j7xr0nbz5k1thybedymf)) > While most researchers agree that presence is one of the most noticeable psychophysical effects of immersive virtual reality (Waltemate et al. 2018), there is little agreement on how to best define this concept. In fact, there are currently many conceptualizations and definitions of presence, and many different terms are used to refer to the feeling of being there, such as telepresence, co-presence, spatial and social presence, virtual, immersive, perceived, subjective, and so on. For example, presence has been defined as the sense of being located at the place depicted by the virtual displays ( Sheridan 1992), as an all-or-none psychological phenomenon (Slater 2009) associated with the illusion of being present at a location different from the actual location of the physical body (place illusion), which is “a ‘response’ to a system of a certain level of immersion” (Slater 2003). Others define presence as “the feeling of being located in a perceptible external world around the self” (Waterworth et al. 2015), as “the experience of being engaged by the representations of a virtual world” (Jacobson 2002), and as the “perceptual illusion of nonmediation” (Lombard and Ditton 1997; Lombard and Jones 2015). ([View Highlight](https://read.readwise.io/read/01hxv2r5821j8rvpzka4921f5w)) > Slater (2002) has noted that defining presence in terms of the feeling of being there is a category mistake and that the sense of being elsewhere is just one of many contributors to presence. Following this intuition, Riva (2009) defined presence in terms of agency and control: “subjects are ‘present’ if they are able to enact in ([View Highlight](https://read.readwise.io/read/01hxv2vevzg18wrr61d2kfrbn0)) > an external world their intentions” (p. 159). This definition is consistent with the observation that our sense of where we are located largely depends on the sense of an “action-space” (Clark 2003, p. 94). Similarly, Wirth et al.’s (2007) model of presence formation requires two steps: self-localization in a mediated environment and the perception of possibilities for action in that environment. Given that presence is tied to the notion of space by definition, it is not surprising that it is sometimes defined in terms of what can be done in that space. Anthropologists in the 1960s emphasized this dynamic aspect of our perception of space (e.g. Hall 1969). ([View Highlight](https://read.readwise.io/read/01hxv2vcb1gnj0gcwtwbstpy0v)) > The variety of definitions of presence has caused a great deal of confusion regarding what constitutes presence, not only among designers and consumers, but also among scholars, impeding progress in the field (Slater 2003). Thus, tidying up the definitions of presence would be helpful. Since different researchers use the term presence differently, a unifying theory of presence is currently not possible (Water- worth et al. 2015). The International Society for Presence Research (2000) defines presence as a psychological state or subjective perception in which even though part or all of an indi- vidual’s current experience is generated by/or filtered through human-made technology, part or all of the individuals’ perception fails to accurately acknowledge the role of the technology in the experience. Except in the most extreme cases, the individual can indicate correctly that s/he is using the technology, but at some level and to some degree, her/his perceptions overlook that knowledge and objects, events, entities, and environments are perceived as if the technology was not involved in the experience (www.ispr.info/about-presence-2/about- presence/). ([View Highlight](https://read.readwise.io/read/01hxv6d7d0sg9v4bpggxnkjpa6)) > When you are present your perceptual, vestibular, proprioceptive, and autonomic nervous systems are activated in a way similar to that of real life in similar situations. Even though you cognitively know that you are not in the real life situation, you will tend to behave as if you were, and have similar thoughts…. (Slater 2003,p.2) Thus, when the participant feels as being present in an immersive virtual environ- ment, certain knowledge that the environment is mediated is always there, if not in the person’s full awareness, then on its border, ready to enter the focus. It is therefore important to determine the factors that channel the processes related to this awareness and how they lead to shifts between the participant’s feeling of being in and being out of the virtual space. We address these issues in the following sections. ([View Highlight](https://read.readwise.io/read/01hxv6hv9n0mve67s6f2kvgf74)) > Illusion of ownership over a body part or over a whole body has been induced in immersive virtual environments for instance by using synchronized visuo-tactile ([View Highlight](https://read.readwise.io/read/01hxv7ycc736w0hez64t5ghgt4)) > stimulation, as in rubber hand illusion. This way ofmapping of the participant’s body schema onto his/her avatar takes place via afferent or sensory signal correspondences (Bailey et al. 2016). In addition, the mapping can be realized via sensorimotor corre- spondences between the physical body and the virtual body. Thus, virtual reality affords different ways in which body ownership illusion may be induced, involving bottom-up factors, which are related to multisensory integration (visual, motor and tactile stimulation), and top-down factors, which are related to conceptual aspects of the experience, i.e. interpretation of the observed virtual body (e.g. its appearance) (Waltemate et al. 2018). ([View Highlight](https://read.readwise.io/read/01hxv7ypv2x1d5gte18j7wqc54)) > An additional level of complexity is involved when virtual bodies offer affordances different from those of human body, such as an avatar with a tail (Steptoe et al. 2013) or an avatar with three arms (Won et al. 2015). This opens an intriguing question of how far virtual embodiment can go and still allow mapping of virtual objects onto human body schema. > Steptoe et al. (2013) introduced the concept of “extended humanoid avatars” to refer to avatars with fundamentally human form, but with some additional features. In this specific study, avatars had a movable, long tail, extending 0.5 m beyond each arm. The study involved an immersive virtual CAVE-type environment with 32 participants, whose movements were tracked and whose avatars reflected their movements. One halfof participants reported that the avatar’s tail moved in a random and asynchronous way relative to their movements, whereas the other half reported that the avatar’s body moved in a synchronous way and that they could control it by hip movements. Moreover, the participants who controlled avatar’s tail movements experienced anxiety when faced with a virtual threat to the tail. This finding is interesting because it indicates that regardless of the appearance of avatar’s body, these participants were able to experience body ownership, confirming once again the flexibility of the human body schema. ([View Highlight](https://read.readwise.io/read/01hxv8fn6qxswz8y8v46wtcf5s)) > However, regardless of the sense of ownership over the virtual body and the sense of control over its movements, the process of motor prediction differs between a virtual body that has a counterpart in the physical world and a body that does not (Steptoe et al. 2013). Consider as an example an avatar with a tail. Although an intention to move avatar’s tail is followed by an efferent signal to the hip muscles which perform the movement and afferent signal from proprioception is sent to the brain, and although the visual signal confirms the hip movement as well as the presence and the movement of the tail, the tail’s movement itself cannot be felt. And this is what sets apart the avatar’s tail movement experience from the normal body movement experience and places it closer to a phantom limb experience. While in the phantom limb experiences people can sense but cannot see the movement, in the avatar tail experience participants can see but cannot sense the movement. The dominance of the visual feedback in the case of avatar with a tail may attenuate, but it cannot compensate for the lack of feedback on how the tail’s movement feels. > The Steptoe et al.’s observation is significant, because it suggests a clear demar- cation between virtual embodiment based on human-like and extended humanoid avatars. The difference has implications for design of virtual reality applications for treatment and training as well as entertainment. On a theoretical level, it suggests the importance of studying effects of virtual embodiment. For instance, one relevant question is: Can a movement that is not felt still be believable? Apparently, even if it is not felt, as long as themovement can be seen and is synchronized with participant’s movements, it is believable. And being believable is what countsmost in this context, or what makes virtual reality feel real (Brooks 2003). Research evidence converges in indicating that the first-person perspective, visuo-tactile and visuo-motor synchrony as well as sensory feedback are critical steps in inducing virtual embodiment, and that even just observing a virtual body from the first person perspective leads to virtual embodiment (Slater et al. 2010). ([View Highlight](https://read.readwise.io/read/01hxv8mpash2b4hkb21qt5sedj)) > While partici- pants were able to relatively quickly (~10 min) adapt to the movement afforded by a new avatar, there were no statistically significant differences in task performance between the avatar who used a longer third arm and the avatar in the normal condi- tion. The authors argue that it may not be the human/non-human-like appearance of an avatar, but rather the control of action that is critical for virtual embodiment. This study provides further evidence that there is flexibility in embodiment of virtual bodies, and that the body can learn to remap movements from the real world to movements of a virtual body despite the structural differences ([View Highlight](https://read.readwise.io/read/01hxv8pxj1maxewb6yw9jxzn4z)) > Apart from the virtual limb illusion, a whole virtual body illusion has also been generated in virtual environments (Petkova and Ehrsson 2008; Mel Slater 2008; Slater et al. 2009; Sanchez-Vives et al. 2010), indicating that these types of illusions are easily replicated in virtual reality (Normand et al. 2011). Critical in inducing the virtual hand illusion, for instance, is synchrony between visual and motor actions of the real and virtual hands, and in the whole body illusion, in addition to synchronous visual-tactile stimulation, first person perspective is necessary. These illusions cannot be produced with asynchronous stimulation. ([View Highlight](https://read.readwise.io/read/01hy05cy36mnasdmf72pm1kb7h)) > Furthermore, body space has been manipulated in virtual reality to induce illusions of different size or shape of one’s body. For instance, the very long arm illusion is characterized by the ownership ofvirtual arm that is up to three times the length of the person’s real arm (Kilteni et al. 2012). While the illusion of shrinking waist has been demonstrated using fMRI (Ehrsson et al. 2005), the opposite, larger belly illusion was generated in virtual reality (Normand et al. 2011). Beside bodily features that are susceptible to change in the course of life, such as belly size, some more rigidly fixed features related to one’s body are also susceptible to body ownership illusion. For instance, a person’s sex has been manipulated in a whole body ownership illusion, which induced illusion of having female bodies in men (Slater et al. 2010a). Here, too, first person perspective and synchronous multisensory stimulation (visuo-tactile) were critical in generating the illusion. ([View Highlight](https://read.readwise.io/read/01hy05d28ewb8830eezjahmrhp)) > These findings have important implications for debates revolving around questions such as: Does the form of human body need to be maintained in virtual reality? If the way the brain represents the body depends both on prior knowledge about human body and on incoming multisensory information, then a certain balance between the two sources ofinformationmust bemaintained to incorporate a virtual representation into the participant’s body schema. As studies on virtual hand illusion show, the main features of the actual body are critical in deceiving the perceptual system by a virtual hand. For the illusion to succeed, there needs to be a sense of body continuity, i.e. visual experience that the virtual hand belongs to the body. Any anatomically implausible alignment between the virtual hand and the real hand or the rest of the body as well as deviations from the real, such as the length of the virtual arm that makes it difficult to see the hand’s details or hand’s texture, affects the illusion (Normand et al. 2011; Kilteni et al. 2012; Perez-Marcos et al. 2012). > Thus, expectations of certain physicality of the body that characterizes normal human experience extend to virtual environments, but they can be modified to some extent. ([View Highlight](https://read.readwise.io/read/01hy05dn6pfpr42h8w6ber55g5)) > Ultimately, virtual reality is about making systems that fool the human senses ([View Highlight](https://read.readwise.io/read/01hy05e160zxh6mxd4s8x0bref)) > With the exception of looking oneself in a mirror, everyday life actions normally allow us to visually perceive our bodies only partially. In addition, the received visual information is typically combined with the tactile and proprioceptive information about our bodies (Knoblich 2002). Taken together, these different types of information form an inter-modal representation of a person’s body, which is sometimes referred to as body image (Gallagher 2000). However, as any other instance of consciousness and cognition at play, self-recognition requires an agent—an experiencing, thinking self (Jeannerod 2003; Knoblich et al. 2003). ([View Highlight](https://read.readwise.io/read/01hy05fvqyyxca87ez30frx3dr)) > An individual’s ability to recognize herself as the agent of a specific behavior also depends on her ability to recognize her body as a behaving body (Jeannerod 2003; Lenggenhager et al. 2007). In a way, the body represents the borders that localize the conscious self. For these reasons, it has been claimed that self-recognition requires both awareness of one’s body3 and awareness of one’s actions (van den Bos and Jeannerod 2002). This “spatial unity” of the conscious self and the body is a hallmark of the normal self-recognition experience (Lenggenhager et al. 2007). ([View Highlight](https://read.readwise.io/read/01hy05hd2kerr4pmmexy1pvqwg))