Virtual Human Plausibility - Evaluation of a measurement tool in virtual reality

Assigned Human-Computer Interaction Master Project Embodiment Lab

1. Introduction
2. Method
3. Research Plan
4. References

1. Introduction

Virtual environments use avatars to represent humans or embodied agents acting as humans [2]. The behaviour and appearance of these avatars have a significant influence on its user and changing a user’s virtual body can influence the way a person behaves [5, 6]. Apart from the influence on its own users, avatars are also seen by other users in the same virtual environment and are thus part of the virtual experience. The behaviour of these human-like avatars has an influence on these users and can even change their behaviour [1]. To measure the influence these avatars have on their respective environments, several measurements are of importance. Arguably the one used the most prominent ones is presence, better described as the feeling of ”being there” [4]. Slater et al. identified two components that have a major influence on presence. Place Illusion (PI), the feeling of the overall environment to be real, and plausibility (PSI), the feeling of the scenario to be able to occur in reality [7]. Recently Latoschik and Wienrich [3] have argued that, while they mostly agree with Slaters definitions, ”there is no plausibility illusion but merely plausibility”. Plausibility is instead based on the coherence of different cognitive layers, namely the sensory, perceptive and cognitive layers. In this project, we want to focus specifically on the plausibility of Virtual Avatars. Previous work by Mal et al. 2022 (in prep.) has created the virtual human plausibility scale questionnaire, a self-assessment questionnaire used to measure the plausibility of virtual avatars. In a previous study the authors evaluated the questionnaires structure in a video-based environment. For this purpose participants were presented with videos of virtual characters that were either realistic-looking or abstract and asked to rate their plausibility using the aforementioned questionnaire. This project aims to recreate this study in a virtual-reality environment

2. Method

The videos from the previous study have been recorded within the Unity Engine [8] v. 2019.4.8f1 using the ViTras project [9]. The study will be adapted to be used in a virtual reality environment using the same technologies. This includes a remodelling of the room the avatars are standing in to be more realistic, detailed and bigger to accommodate the viewer while keeping the angle and distance of the camera true to the previous experiment. Furthermore, it requires features to guide the participants through the procudure, e.g. displayed instructional texts. For the purpose of developing and testing the application an HTC Vive will be used. For the study itself, an Oculus Rift S will be set up in a university lab due to its portability. The questionnaires will be answered using LimeSurvey.

For the study, a total of 30 participants will be recruited using the university’s participant management system . Each participant will be presented with an avatar inside a virtual-reality environment which will play a short pre-recorded idle animation followed by a wave animation. When this is done participants will be asked to take off the VR-headset and given questions about the avatars gender, familiarity and virtual human plausibility. This procedure will be repeated 10 times for each participant with a different avatar each time. Of the avatars 6 will be realistic-looking.

3. Research Plan

4. References

[1] Jeremy N. Bailenson, Jim Blascovich, Andrew C. Beall, and Jack M. Loomis. “Equilibrium Theory Revisited: Mutual Gaze and Personal Space in Virtual Environments.” In: Presence: Teleoperators and Virtual Environments 10.6 (2001), pp. 583–598. DOI: 10.1162/105474601753272844.

[2] Jeremy N. Bailenson, Kim Swinth, Crystal Hoyt, Susan Persky, Alex Dimov, and Jim Blascovich. “The Independent and Interactive Effects of Embodied-Agent Appearance and Behavior on Self-Report, Cognitive, and Behavioral Markers of Copresence in Immersive Virtual Environments.” In: Presence: Teleoperators and Virtual Environments 14.4 (2005), pp. 379–393. DOI: 10.1162/105474605774785235.

[3] Marc Erich Latoschik and Carolin Wienrich. Coherence and Plausibility, not Presence?! Pivotal Conditions for XR Experiences and Effects, a Novel Model. 2021.

[4] Matthew Lombard and Theresa Ditton. “At the Heart of It All: The Concept of Presence.” In: Journal of ComputerMediated Communication 3.2 (1997), p. 0. DOI: 10.1111/j.1083-6101.1997.tb00072.x.

[5] Lara Maister, Mel Slater, Maria V. Sanchez-Vives, and Manos Tsakiris. “Changing bodies changes minds: owning another body affects social cognition.” In: Trends in cognitive sciences 19.1 (2015), pp. 6–12. DOI: 10.1016/j.tics.2014.11.001.

[6] Tabitha C. Peck, Sofia Seinfeld, Salvatore M. Aglioti, and Mel Slater. “Putting yourself in the skin of a black avatar reduces implicit racial bias.” In: Consciousness and cognition 22.3 (2013), pp. 779–787. DOI: 10.1016/j.concog.2013.04.016.

[7] Mel Slater. “Place illusion and plausibility can lead to realistic behaviour in immersive virtual environments.” In: Philosophical transactions of the Royal Society of London. Series B, Biological sciences 364.1535 (2009), pp. 3549–3557. DOI: 10.1098/rstb.2009.0138.

[8] Unity. URL: https://unity.com/.

[9] ViTras - Virtual Reality Therapy by Stimulation of Modulated Body Perception. URL: http://hci.uni-wuerzburg.de/projects/vitras/.

Author Note

The project has been assigned to Philipp Coblenz, who is the author of this summary.

Contact Persons at the University Würzburg