Christian Merz

Christian Merz, B.Sc.

Wissenschaftlicher Mitarbeiter

Research Assistant

Psychologie Intelligenter Interaktiver Systeme
Julius-Maximilians-Universität Würzburg
Institut für Mensch-Computer-Medien
Universität Würzburg
Emil-Fischer-Straße 50
97074 Würzburg
Deutschland

Mini-CV

Studied Human-Computer-Systems (B.Sc.) at the University of Würzburg (2015-2019).
Worked as student assistant for the HCI Group Würzburg (2018).
Worked as student assistant for the XR Hub Würzburg (2019-2021).
Enrolled in the master's programm Human-Computer-Interaction at the University of Würzburg (Since 2019).
Scientific Intership at the PIIS Group with focus on developing aVeRsive, a therapeutic VR application for the treatment of borderline patients (2021).
Research assistant in the BMBF-funded project HiAvA (Since 2021).

Research Interests

Virtual Reality
Extended Reality
Social Virtual Reality

Publications

2025[ to top ]

Merz, Christian, Carolin Wienrich, and Marc Erich Latoschik. “Does Task Matter? Task-Dependent Effects of Cross-Device Collaboration on Social Presence”. In 2025 IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (IEEE VRW). IEEE Computer Science, 2025.
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In this work, we explored asymmetric collaboration under two distinct tasks: collaborative sorting and conversational talking tasks. We answer the research question of how different tasks impact the user experience in asymmetric interaction. Our mixed design compared one symmetric and one asymmetric interaction and two tasks, assessing self-perception (presence, embodiment), other-perception (co-presence, social presence, plausibility), and task perception (task load, enjoyment). 52 participants collaborated in dyads on the two tasks, either using head-mounted displays (HMDs) or one participant using an HMD and the other a desktop setup. Results indicate that differences in social presence diminished or disappeared during the purely conversational talking task in comparison to the sorting task. This indicates that differences in how we perceive a social interaction, which is caused by asymmetric interaction, only occur during specific use cases. These findings underscore the critical role of task characteristics in shaping users’ social XR experiences and highlight that asymmetric collaboration can be effective across different use cases and is even on par with symmetric interaction during conversations.

@inproceedings{merz2025taskasymmetry, abstract = {In this work, we explored asymmetric collaboration under two distinct tasks: collaborative sorting and conversational talking tasks. We answer the research question of how different tasks impact the user experience in asymmetric interaction. Our mixed design compared one symmetric and one asymmetric interaction and two tasks, assessing self-perception (presence, embodiment), other-perception (co-presence, social presence, plausibility), and task perception (task load, enjoyment). 52 participants collaborated in dyads on the two tasks, either using head-mounted displays (HMDs) or one participant using an HMD and the other a desktop setup. Results indicate that differences in social presence diminished or disappeared during the purely conversational talking task in comparison to the sorting task. This indicates that differences in how we perceive a social interaction, which is caused by asymmetric interaction, only occur during specific use cases. These findings underscore the critical role of task characteristics in shaping users’ social XR experiences and highlight that asymmetric collaboration can be effective across different use cases and is even on par with symmetric interaction during conversations.}, author = {Merz, Christian and Wienrich, Carolin and Latoschik, Marc Erich}, booktitle = {2025 IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (IEEE VRW)}, keywords = {merz}, month = {03}, note = {To be published}, publisher = {IEEE Computer Science}, title = {Does Task Matter? Task-Dependent Effects of Cross-Device Collaboration on Social Presence}, year = 2025 }
Tschanter, Jonathan, Christian Merz, Carolin Wienrich, and Marc Erich Latoschik. “Towards Understanding Harassment in Social Virtual Reality: A Study Design on the Impact of Avatar Self-Similarity”. In 2025 IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (IEEE VRW). IEEE Computer Science, 2025.
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In social virtual reality (VR), harassment persists as a pervasive and critical issue. Prior work emphasizes its perceived realness and emotional impact. However, the influence of avatar design, particularly the role of self-similarity, remains underexplored. Self-similar avatars can enhance user identification and engagement, yet potentially intensify the psychological and physiological effects of harassment. Existing studies often rely on interviews or user-generated content, lacking systematic analysis and controlled comparisons. To address these gaps, we present a process for creating realistic VR harassment scenarios. We built a scenario based on existing literature and validated it with expert reviews and user feedback. We propose a 2 x 2 between-subjects design to systematically examine users' emotional and physiological states, their identification with avatars, and the effects of avatar self-similarity. The study design will deepen the understanding of harassment dynamics in VR. Additionally, it can provide actionable insights for designing safer, more inclusive virtual environments that promote user well-being and foster equitable communities.

@inproceedings{noauthororeditor, abstract = {In social virtual reality (VR), harassment persists as a pervasive and critical issue. Prior work emphasizes its perceived realness and emotional impact. However, the influence of avatar design, particularly the role of self-similarity, remains underexplored. Self-similar avatars can enhance user identification and engagement, yet potentially intensify the psychological and physiological effects of harassment. Existing studies often rely on interviews or user-generated content, lacking systematic analysis and controlled comparisons. To address these gaps, we present a process for creating realistic VR harassment scenarios. We built a scenario based on existing literature and validated it with expert reviews and user feedback. We propose a 2 x 2 between-subjects design to systematically examine users' emotional and physiological states, their identification with avatars, and the effects of avatar self-similarity. The study design will deepen the understanding of harassment dynamics in VR. Additionally, it can provide actionable insights for designing safer, more inclusive virtual environments that promote user well-being and foster equitable communities.}, author = {Tschanter, Jonathan and Merz, Christian and Wienrich, Carolin and Latoschik, Marc Erich}, booktitle = {2025 IEEE Conference on Virtual Reality and 3D User Interfaces Abstracts and Workshops (IEEE VRW)}, keywords = {merz}, month = {03}, note = {To be published}, publisher = {IEEE Computer Science}, title = {Towards Understanding Harassment in Social Virtual Reality: A Study Design on the Impact of Avatar Self-Similarity}, year = 2025 }

2024[ to top ]

Merz, Christian, Carolin Wienrich, and Marc Erich Latoschik. “Does Voice Matter? The Effect of Verbal Communication and Asymmetry on the Experience of Collaborative Social XR”. In 23rd IEEE International Symposium on Mixed and Augmented Reality (ISMAR), 1127-36. IEEE Computer Society, 2024. https://doi.org/10.1109/ISMAR62088.2024.00129.
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This work evaluates how the asymmetry of device configurations and verbal communication influence the user experience of social eXtended Reality (XR) for self-perception, other-perception, and task perception. We developed an application that enables social collaboration between two users with varying device configurations. We compare the conditions of one symmetric interaction, where both device configurations are Head-Mounted Displays (HMDs) with tracked controllers, with the conditions of one asymmetric interaction, where one device configuration is an HMD with tracked controllers and the other device configuration is a desktop screen with a mouse. In our study, 52 participants collaborated in a dyadic interaction on a sorting task while talking to each other. We compare our results to previous work that evaluated the same scenario without verbal communication. In line with prior research, self-perception is influenced by the immersion of the used device configuration and verbal communication. While co-presence was not affected by the device configuration or the inclusion of verbal communication, social presence was only higher for HMD configurations that allowed verbal communication. Task perception was hardly affected by the device configuration or verbal communication. We conclude that the device in social XR is important for self-perception with or without verbal communication. However, the results indicate that the device configuration only affects the qualities of social interaction in collaborative scenarios when verbal communication is enabled. To sum up, asymmetric collaboration maintains the high quality of self-perception and interaction for highly immersed users while still enabling the participation of less immersed users.

@inproceedings{merz2024voice, abstract = {This work evaluates how the asymmetry of device configurations and verbal communication influence the user experience of social eXtended Reality (XR) for self-perception, other-perception, and task perception. We developed an application that enables social collaboration between two users with varying device configurations. We compare the conditions of one symmetric interaction, where both device configurations are Head-Mounted Displays (HMDs) with tracked controllers, with the conditions of one asymmetric interaction, where one device configuration is an HMD with tracked controllers and the other device configuration is a desktop screen with a mouse. In our study, 52 participants collaborated in a dyadic interaction on a sorting task while talking to each other. We compare our results to previous work that evaluated the same scenario without verbal communication. In line with prior research, self-perception is influenced by the immersion of the used device configuration and verbal communication. While co-presence was not affected by the device configuration or the inclusion of verbal communication, social presence was only higher for HMD configurations that allowed verbal communication. Task perception was hardly affected by the device configuration or verbal communication. We conclude that the device in social XR is important for self-perception with or without verbal communication. However, the results indicate that the device configuration only affects the qualities of social interaction in collaborative scenarios when verbal communication is enabled. To sum up, asymmetric collaboration maintains the high quality of self-perception and interaction for highly immersed users while still enabling the participation of less immersed users.}, author = {Merz, Christian and Wienrich, Carolin and Latoschik, Marc Erich}, booktitle = {23rd IEEE International Symposium on Mixed and Augmented Reality (ISMAR)}, keywords = {merz}, pages = {1127-1136}, publisher = {IEEE Computer Society}, title = {Does Voice Matter? The Effect of Verbal Communication and Asymmetry on the Experience of Collaborative Social XR}, year = 2024 }
Merz, Christian, Jonathan Tschanter, Florian Kern, Jean-Luc Lugrin, Carolin Wienrich, and Marc Erich Latoschik. “Pipelining Processors for Decomposing Character Animation”. In 30th ACM Symposium on Virtual Reality Software and Technology. VRST ’24. Trier, Germany: Association for Computing Machinery, 2024. https://doi.org/10.1145/3641825.3689533.
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This paper presents an openly available implementation of a modular pipeline architecture for character animation. It effectively decomposes frequently necessary processing steps into dedicated character processors, such as copying data from various motion sources, applying inverse kinematics, or scaling the character. Processors can easily be parameterized, extended (e.g., with AI), and freely arranged or even duplicated in any order necessary, greatly reducing side effects and fostering fine-tuning, maintenance, and reusability of the complex interplay of real-time animation steps.

@inproceedings{merz2024processor, abstract = {This paper presents an openly available implementation of a modular pipeline architecture for character animation. It effectively decomposes frequently necessary processing steps into dedicated character processors, such as copying data from various motion sources, applying inverse kinematics, or scaling the character. Processors can easily be parameterized, extended (e.g., with AI), and freely arranged or even duplicated in any order necessary, greatly reducing side effects and fostering fine-tuning, maintenance, and reusability of the complex interplay of real-time animation steps.}, address = {New York, NY, USA}, author = {Merz, Christian and Tschanter, Jonathan and Kern, Florian and Lugrin, Jean-Luc and Wienrich, Carolin and Latoschik, Marc Erich}, booktitle = {30th ACM Symposium on Virtual Reality Software and Technology}, keywords = {merz}, publisher = {Association for Computing Machinery}, series = {VRST '24}, title = {Pipelining Processors for Decomposing Character Animation}, year = 2024 }
Merz, Christian, Christopher Göttfert, Carolin Wienrich, and Marc Erich Latoschik. “Universal Access for Social XR Across Devices: The Impact of Immersion on the Experience in Asymmetric Virtual Collaboration”. In Proceedings of the 31st IEEE Virtual Reality Conference (VR ’24). IEEE, 2024. https://doi.org/10.1109/VR58804.2024.00105.
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This article investigates the influence of input/output device characteristics and degrees of immersion on the User Experience (UX) of specific eXtended Reality (XR) effects, i.e., presence, self-perception, other-perception, and task perception. It targets universal access to social XR, where dedicated XR hardware is unavailable or can not be used, but participation is desirable or even necessary. We compare three different device configurations: (i) desktop screen with mouse, (ii) desktop screen with tracked controllers, and (iii) Head-Mounted Display (HMD) with tracked controllers. 87 participants took part in collaborative dyadic interaction (a sorting task) with asymmetric device configurations in a specifically developed social XR. In line with prior research, the sense of presence and embodiment were significantly lower for the desktop setups. However, we only found minor differences in task load and no differences in usability and enjoyment of the task between the conditions. Additionally, the perceived humanness and virtual human plausibility of the other were not affected, no matter the device used. Finally, there was no impact regarding co-presence and social presence independent of the level of immersion of oneself or the other. We conclude that the device in social XR is important for self-perception and presence. However, our results indicate that the devices do not affect important UX and usability aspects, specifically, the qualities of social interaction in collaborative scenarios, paving the way for universal access to social XR encounters and significantly promoting participation.

@inproceedings{merz2024universal, abstract = {This article investigates the influence of input/output device characteristics and degrees of immersion on the User Experience (UX) of specific eXtended Reality (XR) effects, i.e., presence, self-perception, other-perception, and task perception. It targets universal access to social XR, where dedicated XR hardware is unavailable or can not be used, but participation is desirable or even necessary. We compare three different device configurations: (i) desktop screen with mouse, (ii) desktop screen with tracked controllers, and (iii) Head-Mounted Display (HMD) with tracked controllers. 87 participants took part in collaborative dyadic interaction (a sorting task) with asymmetric device configurations in a specifically developed social XR. In line with prior research, the sense of presence and embodiment were significantly lower for the desktop setups. However, we only found minor differences in task load and no differences in usability and enjoyment of the task between the conditions. Additionally, the perceived humanness and virtual human plausibility of the other were not affected, no matter the device used. Finally, there was no impact regarding co-presence and social presence independent of the level of immersion of oneself or the other. We conclude that the device in social XR is important for self-perception and presence. However, our results indicate that the devices do not affect important UX and usability aspects, specifically, the qualities of social interaction in collaborative scenarios, paving the way for universal access to social XR encounters and significantly promoting participation.}, author = {Merz, Christian and Göttfert, Christopher and Wienrich, Carolin and Latoschik, Marc Erich}, booktitle = {Proceedings of the 31st IEEE Virtual Reality conference (VR '24)}, keywords = {merz}, organization = {IEEE}, title = {Universal Access for Social XR Across Devices: The Impact of Immersion on the Experience in Asymmetric Virtual Collaboration}, year = 2024 }

2022[ to top ]

Bartl, Andrea, Christian Merz, Daniel Roth, and Marc Erich Latoschik. “The Effects of Avatar and Environment Design on Embodiment, Presence, Activation, and Task Load in a Virtual Reality Exercise Application”. In IEEE International Symposium on Mixed and Augmented Reality (ISMAR). https://downloads.hci.informatik.uni-wuerzburg.de/2022-ismar-ilast-avatar-environment-design-vr-exercise-application.pdf.
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ABSTRACT The development of embodied Virtual Reality (VR) systems involves multiple central design choices. These design choices affect the user perception and therefore require thorough consideration. This article reports on two user studies investigating the influence of common design choices on relevant intermediate factors (sense of embodiment, presence, motivation, activation, and task load) in a VR application for physical exercises. The first study manipulated the avatar fidelity (abstract, partial body vs. anthropomorphic, full-body) and the environment (with vs. without mirror). The second study manipulated the avatar type (healthy vs. injured) and the environment type (beach vs. hospital) and, hence, the avatar-environment congruence. The full-body avatar significantly increased the sense of embodiment and decreased mental demand. Interestingly, the mirror did not influence the dependent variables. The injured avatar significantly increased the temporal demand. The beach environment significantly reduced the tense activation. On the beach, participants felt more present in the incongruent condition embodying the injured avatar.

@inproceedings{bartl2022effects, abstract = {ABSTRACT The development of embodied Virtual Reality (VR) systems involves multiple central design choices. These design choices affect the user perception and therefore require thorough consideration. This article reports on two user studies investigating the influence of common design choices on relevant intermediate factors (sense of embodiment, presence, motivation, activation, and task load) in a VR application for physical exercises. The first study manipulated the avatar fidelity (abstract, partial body vs. anthropomorphic, full-body) and the environment (with vs. without mirror). The second study manipulated the avatar type (healthy vs. injured) and the environment type (beach vs. hospital) and, hence, the avatar-environment congruence. The full-body avatar significantly increased the sense of embodiment and decreased mental demand. Interestingly, the mirror did not influence the dependent variables. The injured avatar significantly increased the temporal demand. The beach environment significantly reduced the tense activation. On the beach, participants felt more present in the incongruent condition embodying the injured avatar.}, author = {Bartl, Andrea and Merz, Christian and Roth, Daniel and Latoschik, Marc Erich}, booktitle = {IEEE International Symposium on Mixed and Augmented Reality (ISMAR)}, keywords = {merz}, title = {The Effects of Avatar and Environment Design on Embodiment, Presence, Activation, and Task Load in a Virtual Reality Exercise Application}, year = 2022 }

Hubland Nord, Gebäude 50

Wissenschaftlicher Mitarbeiter

Mini-CV

Research Interests

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