Good for the Planet, Bad for Me? Intended and Unintended Consequences of AI Energy Consumption DisclosureTo address the high energy consumption of artificial intelligence, energy consumption disclosure (ECD) has been proposed to steer users toward more sustainable practices, such as choosing efficient small language models (SLMs) over large language models (LLMs). This presents a performance-sustainability trade-off for users. In an experiment with 365 participants, we explore the impact of ECD and the perceptual and behavioral consequences of choosing an SLM over an LLM. Our findings reveal that ECD is a highly effective measure to nudge individuals toward a pro-environmental choice, increasing the odds of choosing an energy efficient SLM over an LLM by more than 12. Interestingly, this choice did not significantly impact subsequent behavior, as individuals who selected an SLM and those who selected an LLM demonstrated similar prompt behavior. Nevertheless, the choice created a perceptual bias. A placebo effect emerged, with individuals who selected the "eco-friendly" SLM reporting significantly lower satisfaction and perceived quality. These results highlight the double-edged nature of ECD, which holds critical implications for the design of sustainable human-computer interactions.2026MKMichael Klesel et al.Frankfurt University of Applied ScienceAI-Assisted Decision-Making & AutomationSustainable HCIEnergy Conservation Behavior & InterfacesCHI
Investigating the Impact of Customized Avatars and the Proteus Effect during Physical Exercise in Virtual RealityVirtual reality (VR) allows to embody avatars. Coined the Proteus effect, an avatar's visual appearance can influence users' behavior and perception. Recent work suggests that athletic avatars decrease perceptual and physiological responses during VR exercise. However, such effects can fail to occur when users do not experience avatar ownership and identification. While customized avatars increase body ownership and identification, it is unclear whether they improve the Proteus effect. We conducted a study with 24 participants to determine the effects of athletic and non-athletic avatars that were either customized or randomly assigned. We developed a customization editor to allow creating customized avatars. We found that customized avatars reduced perceived exertion. We also found that athletic avatars decreased heart rate while holding weights, however, only when being customized. Results indicate that customized avatars can positively influence users during physical exertion. We discuss the utilization of avatar customization in VR exercise systems.2025MKMartin Kocur et al.University of Applied Sciences Upper AustriaIdentity & Avatars in XRFitness Tracking & Physical Activity MonitoringCHI
Improving Electromyographic Muscle Response Times through Visual and Tactile Prior Stimulation in Virtual RealityElectromyography (EMG) enables hands-free interactions by detecting muscle activity at different human body locations. Previous studies have demonstrated that input performance based on isometric contractions is muscle-dependent and can benefit from synchronous biofeedback. However, it remains unknown whether stimulation before interaction can help to localize and tense a muscle faster. In a response-based VR experiment (N=21), we investigated whether prior stimulation using visual or tactile cues at four different target muscles (biceps, triceps, upper leg, calf) can help reduce the time to perform isometric muscle contractions. The results show that prior stimulation decreases EMG reaction times with visual, vibrotactile, and electrotactile cues. Our experiment also revealed important findings regarding learning and fatigue at the different body locations. We provide qualitative insights into the participants' perceptions and discuss potential reasons for the improved interaction. We contribute with implications and use cases for prior stimulated muscle activation.2024JSJessica Sehrt et al.Frankfurt University of Applied SciencesElectrical Muscle Stimulation (EMS)Full-Body Interaction & Embodied InputVR Medical Training & RehabilitationCHI
The Effects of Avatar and Environment on Thermal Perception and Skin Temperature in Virtual RealityHumans' thermal regulation and subjective perception of temperature is highly plastic and depends on the visual appearance of the surrounding environment. Previous work shows that an environment’s color temperature affects the experienced temperature. As virtual reality (VR) enables visual immersion, recent work suggests that a VR scene's color temperature also affects experienced temperature. It is, however, unclear if an avatar’s appearance also affects users’ thermal perception and if a change in thermal perception even influences the body temperature. Therefore, we conducted a study with 32 participants performing a task in an ice or fire world while having ice or fire hands. We show that being in a fire world or having fire hands increases the perceived temperature. We even show that having fire hands decreases the hand temperature compared to having ice hands. We discuss the implications for the design of VR systems and future research directions.2023MKMartin Kocur et al.University of RegensburgImmersion & Presence ResearchIdentity & Avatars in XRCHI
The Effects of Body Location and Biosignal Feedback Modality on Performance and Workload using Electromyography in Virtual RealityUsing biosignals through electromyography (EMG) and rendering them as feedback for hands-free interaction finally migrates to engaging virtual reality (VR) experiences for health and fitness-related applications. Previous work proposes various body locations as input sources and different output modalities for creating effective biofeedback loops. However, it is currently unknown which muscles and sensory modalities can provide optimal real-time interaction regarding the performance and perceived workload of the users. In two VR studies (N=18 and N=40) based on a Fitts' law target selection task, we explored sensor placement at different body locations and investigate auditory, tactile, and visual feedback modalities. Objective and subjective results indicate that input performance can be improved by presenting muscle tension as simultaneous tactile and visual feedback. We contribute with recommendations for registration of isometric muscle contraction at different body locations and conclude that reproducing physiological feedback through multimodal channels can assist users interacting with EMG devices.2023JSJessica Sehrt et al.Frankfurt University of Applied SciencesElectrical Muscle Stimulation (EMS)VR Medical Training & RehabilitationCHI
Physiological and Perceptual Responses to Athletic Avatars while Cycling in Virtual RealityAvatars in virtual reality (VR) enable embodied experiences and induce the Proteus effect - a shift in behavior and attitude to mimic one's digital representation. Previous work found that avatars associated with physical strength can decrease users' perceived exertion when performing physical tasks. However, it is unknown if an avatar's appearance can also influence the user's physiological response to exercises. Therefore, we conducted an experiment with 24 participants to investigate the effect of avatars' athleticism on heart rate and perceived exertion while cycling in VR following a standardized protocol. We found that the avatars' athleticism has a significant and systematic effect on users' heart rate and perceived exertion. We discuss potential moderators such as body ownership and users' level of fitness. Our work contributes to the emerging area of VR exercise systems.2021MKMartin Kocur et al.University of RegensburgMotion Sickness & Passenger ExperienceFull-Body Interaction & Embodied InputCHI
Reading in VR: The Effect of Text Presentation Type and LocationReading is a fundamental activity to obtain information both in the real and the digital world. Virtual reality (VR) allows novel approaches for users to view, read, and interact with a text. However, for efficient reading, it is necessary to understand how a text should be displayed in VR without impairing the VR experience. Therefore, we conducted a study with 18 participants to investigate text presentation type and location in VR. We compared world-fixed, edge-fixed, and head-fixed text locations. Texts were displayed using Rapid Serial Visual Presentation (RSVP) or as a paragraph. We found that RSVP is a promising presentation type for reading short texts displayed in edge-fixed or head-fixed location in VR. The paragraph presentation type using world-fixed or edge-fixed location is promising for reading long text if movement in the virtual environment is not required. Insights from our study inform the design of reading interfaces for VR applications.2021RRRufat Rzayev et al.University of RegensburgImmersion & Presence ResearchInteractive Data VisualizationVisualization Perception & CognitionCHI
Implementation and In Situ Assessment of Contextual Privacy PoliciesOnline services collect an increasing amount of data about their users. Privacy policies are currently the only common way to inform users about the kinds of data collected, stored and processed by online services. Previous work showed that users do not read and understand privacy policies, due to their length, difficult language, and often non-prominent location. Embedding privacy-relevant information directly in the context of use could help users understand the privacy implications of using online services. We implemented Contextual Privacy Policies (CPPs) as a browser extension and provide it to the community to make privacy information accessible for end-users. We evaluated CPPs through a one-week deployment and in situ questionnaires as well as pre- and post-study interviews. We found that CPPs were well received by participants. The analysis revealed that provided information should be as compact as possible, be adjusted to user groups and enable users to take action.2020AOAnna-Marie Ortloff et al.Privacy by Design & User ControlPrivacy Perception & Decision-MakingIoT Device PrivacyDIS