SIGCHI Extended Abstracts Sample File

VR Animals: Surreal Body Ownership in Virtual Reality Games Andrey Krekhov Sebastian Cmentowski Abstract University of Duisburg-Essen University of Duisburg-Essen The illusion of being someone else and to perceive a virtual Duisburg, 47057, Germany Duisburg, 47057, Germany [email protected] [email protected] body as our own is one of the strengths of virtual reality se- due.de tups. Past research explored that phenomenon regarding Jens Krüger human-like virtual representations. In contrast, our ongoing University of Duisburg-Essen work focuses on playing VR games in the role of an animal. Duisburg, 47057, Germany We present five ways to control three different animals in [email protected] a VR environment. The controls range from third person companion mode to first person full-body tracking. Our exploratory study indicates that virtual body ownership is also applicable to animals, which paves the way to a number of novel, animal-centered game mechanics. Based on interview outcomes, we also discuss possible directions for further research regarding non-humanoid VR experiences in digital games. CCS Concepts •Human-centered computing ! Virtual reality; •Software and its engineering ! Interactive games; Virtual worlds software; Permission to make digital or hard copies of part or all of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation Author Keywords on the first page. Copyrights for third-party components of this work must be honored. For all other uses, contact the Owner/Author. Virtual body ownership; body transfer illusion; animal avatar CHI PLAY ’18 Extended Abstracts, October 28–31, 2018, Melbourne, VIC, Australia control; animal embodiment; virtual reality games. © 2018 Copyright is held by the owner/author(s). ACM ISBN 978-1-4503-5968-9/18/10. DOI: https://doi.org/10.1145/3270316.3271531 Introduction modes for three different animals. We evaluated our mech- Who do we want to be in a game? Sorcerer, rogue, or anisms in an exploratory survey with eight participants. In warrior, these are default roles most gamers would think addition, we repeated parts of the study with two children, of. Even when a game offers more exotic choices for our as we were curious regarding their VBO experiences and avatar, we usually still get a humanoid representation. potential differences compared to adults. Our results indi- Some successful games allow players to at least partly cate that VBO is indeed noticeable even with non-humanoid identify with realistic, non-humanoid avatars. For example, models, and the interview outcomes expose the general Figure 1: Avatars of our study. Black & White [18] incorporated bipedal animals, Gothic interest of participants regarding playing as animals with 2 [25] allowed players to transform into wild animals like the respective set of virtual skills. wolves and scavengers to prevent fights or complete quests, and Deadly Creatures [26] offered combat experiences vs. The contribution of our work in progress report is twofold. other animals while being a tarantula or a scorpion. And Backed by our evaluation, we propose several possibilities although players seemed to enjoy such non-humanoid how animal avatars could be controlled in VR and what mechanics, playable, realistic animals remain a rarity in advantages and disadvantages such modes could have. common digital games, not to mention VR titles. Furthermore, our paper describes a number of possible future experiments that we think are helpful to better under- Our claim is that incorporating animals as player avatars stand the VBO phenomenon in VR games and to establish into VR has the potential to unveil a set of novel game animal control as an engaging game mechanic. mechanics and maybe even lead to a “beastly” VR game genre. Our claim is based on two assumptions. First, VR Related Work Figure 2: Tiger control in the full exposes the phenomenon of virtual body ownership (VBO) [36]. Our work can be classified as research in the areas of VBO body tracking (FB) mode: arm = We suppose that VBO is transferable to non-humanoid char- and player experience in VR. We assume that the latter forepaw, leg = hindpaw. acters, e.g., it is possible to experience the feeling of being concepts are familiar to our community, hence we only in an animal body while playing a VR game. We suggest briefly address them before going into detail regarding VBO. that such a feeling might be an interesting player experi- Player experience [43] refers to aspects such as challenge, ence worth further study. Second, utilizing the abilities of competence, immersion, and flow. The process of measur- animals such as flying as a bird or crawling as a spider ing such components was described by, e.g., IJsselsteijn et could be significantly more engaging in VR due to the in- al. [12, 13] and sublimed into the Game Experience Ques- creased presence compared to non-VR games. tionnaire [14]. Hence, our first step into this direction was to explore Playing in a VR setup adds immersion [5] as an influential whether and how VBO applies to animals in VR. We also factor. As often done by researchers (cf. [2, 31]), we refer to researched how players could control their representation in immersion as the technical quality of a VR equipment and such games, as there often is no straightforward mapping use the term presence [37, 33] when talking about the influ- between human and animal postures. Therefore, we have ence of such equipment on our perception. Several ways Figure 3: FB spider: arm = front implemented two first person and three third person control to measure presence were exposed by, e.g., Lombard et limb, leg = three hindlimbs. al. [19] and IJsselsteijn et al. [15]. Apart from presence, i.e., inhabit non-humanoid avatars with additional body parts. the feeling of being there [11], immersive setups are capa- ble of inducing the illusion of virtual body ownership, also Even more interesting for VR games, Steptoe et al. [38] referred to as body transfer illusion, agency, or embodiment. added a tail-like, controllable body part to the avatar representation. The authors concluded that the tail movements Virtual Body Ownership need to be synchronized to provide a higher degree of body One of the pioneering works regarding VBO was conducted ownership. Another prominent example of body modifica- by Botvinick et al. [3]. The authors detected the so-called tion that could be promising for VR games are virtual wings. rubber hand illusion in an experiment where they hid the In that area, Egeberg et al. [7] exposed several ways how real arm of the participant behind a screen that displayed wing control could be coupled with sensory feedback, and an artificial rubber limb. Both the real and virtual arms were Sikström et al. [32] assessed the influence of sound on then simultaneously stroked by a brush and participants VBO in such scenarios. Regarding realistic avatars, Walte- Figure 4: Human FB mode. reported to sense the touch on the virtual rubber hand. Fur- mate et al. [42] showed that customizable representations ther studies by Tsakiris et al. [41, 40] revisited the rubber lead to significantly higher VBO effects. hand illusion and established a first neurocognitive model that described (virtual) body ownership as an interplay be- As a final remark regarding VBO experience, we point read- tween multisensory input and internal models of the body. ers to the recent work in progress by Roth et al. [29]. In As a follow-up to virtual arms, researchers also extended particular, the paper presented a VBO questionnaire based the experiments to a whole body representation [8, 24, 17]. on a fake mirror scenario study. The authors suggested These early findings were followed by a number of insights to measure acceptance, control, and change as the three regarding the visuotactile correlation [34, 30] and the in- factors that determine VBO. In our experiments, we applied volved visuoproprioceptive cues [35, 23, 21, 36] that help us the proposed questionnaire as we were curious to see how to enhance the VBO illusion. We will not go into more detail it performs for animal avatars. at that point, as the mentioned works focus on anthropomor- There is a body of literature related to the control of animal phic representations and, thus, we cannot assume that the avatars that should be mentioned in this context. Leite et same principles are also applicable for animals. Figure 5: FB bat: arm = wing, leg al. [16] experimented with virtual silhouettes of animals = claw. More related to our research, Lugrin et al. [20] varied the that were used like shadow puppets and controlled by body level of anthropomorphism in their experiments and stated motion. For 3D cases, Rhodin et al. [27] applied sparse cor- that VBO is also noticeable with non-humanoid charac- respondence methods to create a mapping between player ters. Researchers have determined that adding virtual body movements and animal behavior and tested their approach parts does not necessarily destroy the VBO illusion. For in- with species such as spiders and horses. As a next step, stance, Guterstam et al. [10] experimented with a third arm Rhodin at al. [28] experimented with the generalization of that evoked a duplicate touch feeling, while Normand et wave gestures to create control possibilities for, e.g., cater- al. [22] rather focused on creating the illusion of having an pillar crawling movements. Our research extends those enlarged belly. Won et al. [44] further analyzed our ability to methods by presenting additional mechanisms tailored to animal avatar control. Figure 6: Player perspective: looking in a mirror in HB mode.

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