Virtual reality enables immersion in any environment. According to the hue-heat hypothesis, an environment’s color temperature influences thermal perception and regulation, factors important for productivity and energy consumption. Previous work suggests that visual thermal cues, e.g., snowy or desert environments, affect thermal perception and regulation. As color temperature was not controlled, it is unknown if hue or thermal cues caused the effects. In our first study, we derived two virtual environments with cold or warm thermal cues. In the second study, participants experienced these environments with varying hues for 5 minutes. We found that hue influences thermal sensation and thermal cues influence sensation, comfort, and skin temperature. As these effects seem to increase beyond 5 minutes, a third study with longer exposure and more extreme hue differences confirmed and extended these findings. Overall, our results consistently show that hue and visual thermal cues independently affect thermal perception and regulation. This highlights the importance of considering both when designing virtual environments.

Virtual 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.

Perceived temperature and thermoregulation are not only influenced by actual temperature but also by visual perception. For instance, the hue-heat hypothesis posits that warm-colored lighting can increase perceived temperature. Recent work indicates that embodying avatars with visual cues suggesting extreme temperatures influences thermal perception and thermoregulation. However, recent work is limited by short exposure times, inconsistent temperature effects, and the absence of a baseline comparison. Thus, we conducted a study where participants embodied ice, neutral, and fire hands in virtual reality for 15 minutes. We show that thermal sensation is significantly higher with fire hands compared to ice hands, but found no consistent effects on skin temperature. As the effects on thermal sensation remain consistent at least over 15 minutes, we conclude that avatars’ appearance can be used to systematically influence users’ thermal perception.

Outdoor art exhibitions are increasingly popular spaces for people to connect with art. With the rapid advancements in augmented reality and mixed reality, immersive technologies and digital augmentations are transforming how people experience art by incorporating animations and interactive elements. However, though commonly used, marker-based augmented reality approaches present limitations in large outdoor exhibitions, including tedious setups and restricted exploration freedom for users. To address these challenges, we present a markerless mobile AR application utilizing Geospatial tracking to augment murals and playfully enhance outdoor art exhibitions with dynamic animations and interactive features that target the space between exhibits. In this paper, we describe the development of the mobile AR application and explore various interaction concepts in a qualitative in-situ study with 10 participants. Findings demonstrate how our application can be utilized to create innovative, user-centered experiences in outdoor art settings.

Designers of virtual characters use facial expressions to display avatar emotions. Previous work revealed connections between emotions and thermoregulatory, e.g., happiness increases and sadness decreases skin temperature. As virtual reality (VR) enables embodying avatars with any facial expression, it is unclear whether embodying avatars with different emotions also affect users’ thermophysiological and emotional responses. We conducted a study with 24 participants who embodied customized avatars displaying happy, neutral, and sad facial expressions in VR. We found that participants’ skin temperature was higher with sad avatars than with happy ones while resting. Despite non-significant pairwise comparisons, descriptive statistics suggest an opposite trend for skin temperature responses during grabbing interactions. We also show that participants felt happier while embodying happy avatars compared to sad avatars. Results indicate that avatars’ emotions impact users’ thermoregulation and affective states. We discuss underlying mechanisms and potential applications.

Cybersickness remains a persistent challenge in immersive media. Prior work suggests that rendering a virtual nose can reduce cybersickness by providing a stable visual reference. However, if it introduces unwanted perceptual side effects such as changing odor perception or reducing the sense of presence is currently unknown. We conducted a study with 22 participants to examine whether a virtual nose influences odor perception or sense of presence in mixed reality. Except for perceived familiarity of the odor, results provide moderate evidence that rendering a virtual nose does not differ from not rendering one. This indicates that a virtual nose does not significantly influence presence and odor sensitivity. However, future work should further explore how a virtual nose influences perceived familiarity of odors to learn more about perceptual side effects.

Virtual Reality (VR) enables users to embody avatars with vastly different appearances and anatomies. Embodying virtual spiders with their alien morphology could offer exciting experiences for immersive VR in gaming or education. While prior research has explored embodiment of human-like avatars and even non-human forms such as animals, it still remains unclear how best to control anatomically distinct avatars such as spiders. In this exploratory study, we systematically compared four control methods—standard VR controller, hand control, half-body control, and full-body control—while embodying a spider in VR. Using a repeated-measures design with 20 participants, we assessed each control method in terms of embodiment, usability, and perceived exertion. Results indicate that half-body control offered the best overall balance, with the highest usability and lowest exertion, while still maintaining a comparable level of embodiment to other methods. Full-body control was rated significantly lower in usability and higher in perceived exertion. These findings suggest that half-body control may provide a good balance between realism and usability for embodying spiders in VR.

Motion sickness is a prevalent side effect of exposure to virtual reality (VR). Previous work found that pleasant odors can be effective in alleviating symptoms of motion sickness such as nausea. However, it is unknown whether pleasant odors that do not match the anticipated scent of the virtual environment are also effective as they could, in turn, amplify symptoms such as disorientation. Therefore, we conducted a study with 24 participants experiencing a pleasant odor (rose) and an unpleasant odor (garlic) while being immersed in a virtual environment involving either virtual roses or garlic. We found that participants had lower motion sickness when experiencing the rose odor, however, only in the rose environment. Accordingly, we also showed that the sense of disorientation was lower for the rose odor, however, only while being immersed in the rose environment. Results indicate that whether pleasant odors are effective in alleviating motion sickness symptoms depends on the visual appearance of the virtual environment. We discuss possible explanations for such effects to occur. Our work contributes to the goal of mitigating visually induced motion sickness in VR.

With the increasing development of Virtual Reality, locomotion has become an essential component of interaction in VR. Currently, various locomotion technologies have been developed to provide users with a natural walking experience in virtual environments. However, the multiple walking techniques impact users’ walking experience in different ways. Simulator sickness is a common issue in VR experiences. Since different walking methods may influence simulator sickness differently, we conducted a user study to evaluate simulator sickness in walking with three relevant walking methods: real walking, arm-swing, and omnidirectional treadmill, and the results indicated that these three walking methods caused different levels of simulator sickness, and people perceived stronger sickness when they walked on the omnidirectional treadmill.

Perceiving objects’ and avatars’ weight in Virtual Reality (VR) is important to understand their properties and naturally interact with them. However, commercial VR controllers cannot render weight. Controllers presented by previous work are single-handed, slow, or only render a small mass. In this paper, we present PumpVR that renders weight by varying the controllers’ mass according to the properties of virtual objects or bodies. Using a bi-directional pump and solenoid valves, the system changes the controllers’ absolute weight by transferring water in or out with an average error of less than 5%. We implemented VR use cases with objects and avatars of different weights to compare the system with standard controllers. A study with 24 participants revealed significantly higher realism and enjoyment when using PumpVR to interact with virtual objects. Using the system to render body weight had significant effects on virtual embodiment, perceived exertion, and self-perceived fitness.

Humans’ 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.

Virtual reality (VR) allows to embody avatars—the digital self-representation of the user. An avatar’s appearance can change users’ perception and behavior—a phenomenon known as the Proteus effect. Previous work found that athletic avatars can reduce heart rate and perceived exertion during physical effort. Although these findings are promising to create more effective VR exercises, they have not been replicated yet. Hence, the reliability and consistency of such effects is unknown. Therefore, we conducted a study with 32 participants to investigate physiological and perceptual effects of athletic avatars while cycling in VR following a standardized exercise protocol. We could not find effects of the avatars’ athletic appearance on heart rate, perceived exertion, and imagined velocity. Our findings indicate that athletic avatars do not necessarily affect users during physical exertion. We discuss potential factors that can cause the Proteus effect fail to occur.

Avatars are used to represent users in virtual reality (VR) and create embodied experiences. Previous work showed that avatars’ stereotypical appearance can affect users’ physical performance and perceived exertion while exercising in VR. Although sweating is a natural human response to physical effort, surprisingly little is known about the effects of sweating avatars on users. Therefore, we conducted a study with 24 participants to explore the effects of sweating avatars while cycling in VR. We found that visualizing sweat decreases the perceived exertion and increases perceived endurance. Thus, users feel less exerted while embodying sweating avatars. We conclude that sweating avatars contribute to more effective exergames and fitness applications.

Feeling ownership of a virtual body is crucial for immersive experiences in VR. Knowledge about body ownership is mainly based on rubber hand illusion (RHI) experiments in the real world. Watching a rubber hand being stroked while one’s own hidden hand is synchronously stroked, humans experience the rubber hand as their own hand and underestimate the distance between the rubber hand and the real hand (proprioceptive drift). There is also evidence for a decrease in hand temperature. Although the RHI has been induced in VR, it is unknown whether effects in VR and the real world differ. We conducted a RHI experiment with 24 participants in the real world and in VR and found comparable effects in both environments. However, irrespective of the RHI, proprioceptive drift and temperature differences varied between settings. Our findings validate the utilization of the RHI in VR to increase our understanding of embodying virtual avatars.

Avatars 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.

Avatars in virtual reality (VR) can have body structures that differ from the physical self. Game designers, for example, often stylize virtual characters by reducing the number of fingers. Previous work found that the sensation of presence in VR depends on avatar realism and the number of limbs. However, it is currently unknown how the removal of individual fingers affects the VR experience, body perception, and how fingers are used instead. In a study with 24 participants, we investigate the effects of missing fingers and avatar realism on presence, phantom pain perception, and finger usage. Our results show that particularly missing index fingers decrease presence, show the highest phantom pain ratings, and significantly change hand interaction behavior. We found that relative usage of thumb and index fingers in contrast to middle, ring, and little finger usage was higher with abstract hands than with realistic ones – even when the fingers were missing. We assume that dominant fingers are firstly integrated into the own body schema when an avatar does not resemble one’s own appearance. We discuss cognitive mechanisms in experiencing virtual limb loss.

Virtual reality (VR) allows embodying any possible avatar. Known as the Proteus effect, avatars can change users’ behavior and attitudes. Previous work found that embodying Albert Einstein can increase cognitive task performance. The behavioral confirmation paradigm, however, predicts that our behavior is also affected by others’ perception of us. Therefore, we investigated the cognitive performance in collaborative VR when self-perception and external perception of the own avatar differ. 32 male participants performed a Tower of London task in pairs. One participant embodied Einstein or a young adult while the other perceived the participant as Einstein or a young adult. We show that the perception by others affects cognitive performance. The Einstein avatar also decreased the perceived workload. Results imply that avatars’ appearance to both, the user and the others must be considered when designing for cognitively demanding tasks.