Effects of Personalized Avatars in Physical Exercises in Virtual Reality

Assigned Human-Computer Interaction Master Thesis Embodiment Lab

Overview

Virtual reality (VR) has many different uses. While the public focus mostly lies on leisure activities, like virtual chat rooms or shopping, it has more practical uses as well. Using VR to exercise using exergames has proven to increase motivation, thus positively influencing the exercise experience (Finkelstein and Suma, 2011, Li et al., 2014). Exergames can be used to improve health by using them for regular exercise or even for rehabilitation. It has been argued that VR rehabilitation programs have a positive effect on the rehabilitation outcome (Howard, 2017, Costa et al., 2019). An important aspect of VR is the embodiment of avatars. Virtual Reality allows users to be more immersed in a virtual world than ever before. As such the avatar they embody has a significant influence on their experience (Waltemate et al., 2018). Early studies with exergames used 3D projection mapping or similar technologies instead of fully-immersive VR, with no need for an avatar to represent the user. Later fully immersive HMD-based VR experiments implemented full-body avatars to be embodied by the users. Many of them modified specific aspects of these avatars to see how they affected performance (Peña and Kim, 2014, Peña et al., 2016, Kocur et al., 2020). The avatar used in those studies were realistic-looking in nature but did not correspond to the users’ real appearance. The usage of more personalized avatars can have several benefits. Waltemate et al. have found that giving users’ an avatar modelled after themselves, thus creating visual self-similarity, leads to increased body ownership, presence and dominance (Waltemate et al., 2018). Furthermore, increased self-similarity can improve performance in various tasks (Peña et al., 2009, Jang et al., 2010, de Rooij et al., 2017), which, in the context of VR exercise might aid with increasing different factors such as motivation. To our knowledge, no study currently exists about personalized avatars in the context of VR exercise. This master thesis aims to fill this gap, providing insights into using personalized avatars in this context.

Related Work

VR-Exercise

Previous studies with VR exergames have proven to successfully increase several positive factors. Finkelstein et al. (Finkelstein and Suma, 2011) have found a positive relation between gameplay attractiveness and exercise effectiveness, with higher values in gameplay attractiveness leading to higher values in exercise effectiveness, showing the benefit of exergames. The setup used in this did not include a head-mounted display (HMD) in the modern sense but instead used 3D projection mapping and stereoscopic glasses to create a virtual reality environment. While these effects might, on the basis of the technology used, not fully transfer over to modern VR, it still shows the importance of engaging design in VR-Exergames. A meta-analysis by Howard (Howard, 2017) came to similar results. It focused specifically on virtual reality rehabilitation, proposing that virtual reality leads to improved outcomes in this type of therapy. A study using the previously mentioned iLast, conducted by Bartl et al. (Bartl et al., 2022), has focused more on specific design choices for exercising in VR and what influence they have on factors such as motivation or presence. Among other design choices, such as the type environment, it was found that the type of avatar that is used significantly influences a users experience. Higher avatar fidelity, such as a full-body avatar, generally leads to more positive results.

Personalized Avatars

Avatars can be modified to achieve certain behavioural changes, e.g. by invoking the proteus effect, which can according to Yee and Bailenson (Yee and Bailenson, 2007), influence the users’ behaviour to “conform to their digital self-representation” (Yee and Bailenson, 2007). Another way to use avatars is going in the opposite direction and making the avatar more similar to its user and creating Avatar-Self Similarity. Jang et al. (Jang et al., 2010) conducted a survey with players of an MMORPG, asking them questions about their avatars and in-game performance. The survey found a correlation between avatar-self similarity and mastery score, with players that considered the appearance of their avatar similar to their actual appearance generally performing better in the game. A possible explanation they gave was a higher identification or emotional attachment to the avatar. A series of studies by Amyerich-Franch et al. (Aymerich-Franch et al., 2014) have been done about the relationship between social anxiety and personalized avatars. While speaking in front of a virtual audience in a VR-Environment, participants with a selfsimilar avatar experienced higher levels of social anxiety than those who could choose an avatar or were assigned a non-self-similar one, with the non-self-similar avatars achieving the lowest levels of anxiety. This demonstrates that using personalized avatars can also have negative consequences.

Goals

Research exists on both VR exergames and personalized avatars. The main goal of this thesis is to fill the gap and gain more insight into the effects of using personalized avatars inside VR exergames. For this purpose, a VR exergame will be created. It will be implemented into the currently existing project of iLast (Bartl et al., 2022). It will include an exercise that can be used for physical rehabilitation and contain a score that can be used as a performance measure. It should contain a score that can be used as a performance measure. The game should not evoke a strong feeling of flow to not distract from the users’ avatar, but still be immersive enough to possibly improve motivation (Lugrin et al., 2015). A study will be conducted to compare personalized with non-personalized avatars using this exergame. Measured metrics will include the performance score, motivation and presence.

Approach

To achieve this, the following steps will be carried out:

1. Design a participant study to be carried out that uses an exergame and compares personalized to non-personalized avatars.
2. Create or find suitable non-personalized avatars.
3. Conduct a pre-study to identify which non-personalized avatars are best suited for the main study and whether the main study task is understood.
4. Design and implement an interactive VR exergame using Unity and iLast.
5. Conduct the main study, using the implemented exergame with the goal of comparing the effects personalized avatars versus the effects of non-personalized avatars.

References

Aymerich-Franch, L., Kizilcec, R. F., & Bailenson, J. N. (2014). The relationship between virtual self similarity and social anxiety. Frontiers in human neuroscience, 8, 944.

Bartl, A., Merz, C., Roth, D., & Latoschik, M. E. (2022). The effects of avatar and environment design on embodiment, presence, activation, and task load in a virtual reality exercise application. 2022 IEEE international symposium on mixed and augmented reality (ISMAR), 260–269.

Costa, M. T. S., Vieira, L. P., Barbosa, E. d. O., Mendes Oliveira, L., Maillot, P., Ottero Vaghetti, C. A., Giovani Carta, M., Machado, S., Gatica-Rojas, V., & Monteiro-Junior, R. S. (2019). Virtual reality-based exercise with exergames as medicine in different contexts: A short review. Clinical practice and epidemiology in mental health : CP & EMH, 15, 15–20.

de Rooij, A., van der Land, S., & van Erp, S. (2017). The creative proteus effect: How self-similarity, embodiment, and priming of creative stereotypes with avatars influences creative ideation. Proceedings of the 2017 ACM SIGCHI Conference on Creativity and Cognition, 232–236.

Finkelstein, S., & Suma, E. A. (2011). Astrojumper: Motivating exercise with an immersive virtual reality exergame. Presence: Teleoperators and Virtual Environments, 20 (1), 78–92.

Howard, M. C. (2017). A meta-analysis and systematic literature review of virtual reality rehabilitation programs. Computers in Human Behavior, 70 (17), 317– 327.

Jang, Y., Kim, W., & Ryu, S. (2010). An exploratory study on avatar-self similarity, mastery experience and self-efficacy in games. 2010 The 12th International Conference on Advanced Communication Technology (ICACT), 2, 1681–1684.

Kocur, M., Kloss, M., Schwind, V., Wolff, C., & Henze, N. (2020). Flexing muscles in virtual reality: Effects of avatars’ muscular appearance on physical performance. Proceedings of the Annual Symposium on Computer-Human Interaction in Play, 193–205.

Li, B. J., Lwin, M. O., & Jung, Y. (2014). Wii, myself, and size: The influence of proteus effect and stereotype threat on overweight children’s exercise motivation and behavior in exergames. Games for health journal, 3 (1), 40–48.

Lugrin, J.-L., Latt, J., & Latoschik, M. E. (2015). Avatar anthropomorphism and illusion of body ownership in vr. 2015 IEEE Virtual Reality (VR), 229–230.

Peña, J., Hancock, J. T., & Merola, N. A. (2009). The priming effects of avatars in virtual settings. Communication Research, 36 (6), 838–856.

Peña, J., Khan, S., & Alexopoulos, C. (2016). I am what i see: How avatar and opponent agent body size affects physical activity among men playing exergames. Journal of Computer-Mediated Communication, 21 (3), 195–209.

Peña, J., & Kim, E. (2014). Increasing exergame physical activity through self and opponent avatar appearance. Computers in Human Behavior, 41, 262–267.

Waltemate, T., Gall, D., Roth, D., Botsch, M., & Latoschik, M. E. (2018). The impact of avatar personalization and immersion on virtual body ownership, presence, and emotional response. IEEE transactions on visualization and computer graphics, 24 (4), 1643–1652.

Yee, N., & Bailenson, J. (2007). The proteus effect: The effect of transformed selfrepresentation on behavior. Human Communication Research, 33 (3), 271– 290.

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