Like humans, today's systems, such as robots and voice assistants, can express curiosity to learn and engage with their surroundings.While curiosity is a well-established human trait that enhances social connections and drives learning, no existing scales assess the perceived curiosity of systems.Thus, we introduce the Perceived System Curiosity (PSC) scale to determine how users perceive curious systems.We followed a standardized process of developing and validating scales, resulting in a validated 12-item scale with 3 individual sub-scales measuring explorative, investigative, and social dimensions of system curiosity.In total, we generated 831 items based on literature and recruited 414 participants for item selection and 320 additional participants for scale validation.Our results show that the PSC scale has inter-item reliability and convergent and construct validity.Thus, this scale provides an instrument to explore how perceived curiosity influences interactions with technical systems systematically.

Figure 1: The two-phase process for eliciting and verifying gestures.

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This paper examines the impact of AI-generated versus human-written dialogue in a murder-mystery game on player experience. We manipulated both the game dialogue type (AI-generated vs. human-written dialogue) and the game type description (AI-labelled vs human-written-labelled) to assess effects on overall player experience (PX), immersion, and perceived autonomy. Results show that player expectations, modulated by the game type description, had a greater impact on overall PX than the actual game type. Players who thought that they played a game with a human-written narrative reported more positive overall PX, higher immersion and perceived autonomy regardless of which version they actually played. However, interacting with the AI-generated dialogue version led to higher perceived autonomy, suggesting that AI-driven dialogue can enhance perceived freedom without necessarily improving the overall PX. These findings show that player expectations, in response to game descriptions, play a central role in the experiences of players. This work contributes to understanding the influence of narratives and the extent to which AI features increase player engagement.

Thermal sensations are central to how we experience the world, yet most virtual and extended reality systems fail to simulate them effectively. While hardware-based thermal displays can provide accurate temperature changes, they are often bulky, power-intensive, and restrict user mobility. Consequently, recent works have explored thermal illusions, perceptual effects that rely on cross-modal interactions, to achieve thermal experiences without physical heating or cooling. While thermal illusions have been shown to consistently alter subjective ratings, the actual extent of their effect on the perceived temperature of interacted objects remains unexplored. To address this, we contribute the findings of two user studies following psychophysical procedures. We first ordered and scaled the effects of a variety of visual and auditory cues (N=20) and subsequently quantified their isolated and combined efficacy in offsetting physical temperature changes (N=24). We found that thermal illusions elicited robust changes in subjective judgments, and auditory cues showed potential as an alternative or complementary approach to established visual techniques. However, the actual effects induced by thermal illusions were relatively small (±0.5°C) and did not consistently align with abstract ratings, suggesting a need to reconsider how future thermal illusions or experiences are designed and evaluated.

Providing users with realistic sensations of object stiffness in virtual environments remains challenging due to the intricacies of our haptic sense. We investigate the use of a visuo-haptic illusion to alter the perceived stiffness of hand-held objects in virtual reality. We manipulate the Control-to-Display ratio of the index finger and thumb movements during pinching to make virtual objects feel softer or harder. We evaluated this approach on a variety of haptic representations and visualizations we selected through a pre-study survey (N=24). Results of our user study (N=20) demonstrate that this method effectively and reliably modifies stiffness perception, bridging gaps of 50% in physical stiffness without adversely affecting the visuo-haptic experience. Our findings offer insights into how different visual and haptic presentations impact stiffness perception, contributing to more effective and adaptable future haptic feedback systems.

Heightened AI expectations facilitate performance in human-AI interactions through placebo effects. While lowering expectations to control for placebo effects is advisable, overly negative expectations could induce nocebo effects. In a letter discrimination task, we informed participants that an AI would either increase or decrease their performance by adapting the interface, when in reality, no AI was present in any condition. A Bayesian analysis showed that participants had high expectations and performed descriptively better irrespective of the AI description when a sham-AI was present. Using cognitive modeling, we could trace this advantage back to participants gathering more information. A replication study verified that negative AI descriptions do not alter expectations, suggesting that performance expectations with AI are biased and robust to negative verbal descriptions. We discuss the impact of user expectations on AI interactions and evaluation.

The use of AI is becoming more common among the population every day; the use of generative AI, such as LLMs, empowers individuals by supporting daily life tasks. Yet, the user interaction with AI models is mostly constrained to chatbot interactions. However, we envision that in the near future, individuals will be able to integrate the use of these technologies into their daily activities without refocusing their attention. Consequently, we explores the impact of such integration on individuals’ conversations.

In recent years, the community has presented various novel solutions to address the lack of haptic feedback in virtual reality experiences. Yet, it remains a major challenge for Virtual Reality applications. Encountered-type Haptic Displays (ETHDs) have emerged as a promising alternative to enable haptic feedback in VR without requiring the user to wear any device while allowing for sensorily rich experiences such as texture, kinaesthetic feedback, and even ultrasonic tactile feedback. Nevertheless, as important as thermal feedback is for daily life interactions, such as assessing the temperature of a mug or knowing if the microwave is on, thermal feedback in ETHD has remained largely unexplored. In this paper, we present a novel ETHD that provides thermal feedback and explore its potential in VR. We describe the design of our ETHD, and we report the results of a user study that compares different thermal feedback settings in VR. Our results show that thermal feedback can significantly enhance the user immersion and haptic experience in VR, and we discuss the implications of our findings for the design of ETHD and VR experiences.

Rendering realistic tactile sensations of virtual objects remains a challenge in VR. While haptic interfaces have advanced, particularly with phased arrays, their ability to create realistic object properties like state and temperature remains unclear. This study investigates the potential of Ultrasound Mid-air Haptics (UMH) for enhancing the perceived congruency of virtual objects. In a user study with 30 participants, we assessed how UMH impacts the perceived material state and temperature of virtual objects. We also analyzed EEG data to understand how participants integrate UMH information physiologically. Our results reveal that UMH significantly enhances the perceived congruency of virtual objects, particularly for solid objects, reducing the feeling of mismatch between visual and tactile feedback. Additionally, UMH consistently increases the perceived temperature of virtual objects. These findings offer valuable insights for haptic designers, demonstrating UMH's potential for creating more immersive tactile experiences in VR by addressing key limitations in current haptic technologies.

The proliferation of mobile Virtual Reality (VR) headsets shifts our interaction with virtual worlds beyond our living rooms into shared spaces. Consequently, we are entrusting more and more personal data to these devices, calling for strong security measures and authentication. However, the standard authentication method of such devices - entering PINs via virtual keyboards - is vulnerable to shoulder-surfing, as movements to enter keys can be monitored by an unnoticed observer. To address this, we evaluated masking techniques to obscure VR users' input during PIN authentication by diverting their hand movements. Through two experimental studies, we demonstrate that these methods increase users' security against shoulder-surfing attacks from observers without excessively impacting their experience and performance. With these discoveries, we aim to enhance the security of future VR authentication without disrupting the virtual experience or necessitating additional hardware or training of users.

During listening to music, the brain expects specific acoustic events based on learned musical rules. During music performance expectancy is additionally created based on motor action by linking keypresses to their sounds. We investigated EEG (Electroencephalography) signals to auditory expectancy violations in piano performance and perception. In our study, pianists experienced manipulations of different acoustic features, such as pitch and loudness, during playing and listening to piano sequences. We found that manipulations during performance elicited deflections with stronger amplitudes compared to manipulations during perception indicating that the action of producing sounds strengthens auditory expectancy. Loudness manipulations, violating musical regularity, elicited deflections with smaller latencies compared to pitch manipulations, which violate harmonic expectancy, suggesting that the brain processes expectancy violations of distinct acoustic features in a different way. These EEG signatures may prove useful for applications in intelligent music interfaces by providing information about sensory-motor accuracy.

Technologies that help users overcome their limitations and integrate with the human body are often termed “human augmentations”. Such technologies are now available on the consumer market, potentially supporting people in their everyday activities. To date, there is no systematic understanding of the perception of human augmentations yet. To address this gap and build an understanding of how to design positive experiences with human augmentations, we conducted a mixed-method study of the perception of augmented humans (AHs). We conducted two scenario-based studies: interviews (n = 16) and an online study (n = 506) with participants from four countries. The scenarios include one out of three augmentation categories (sensory, motor, and cognitive) and specify if the augmented person has a disability or not. Overall, results show that the type of augmentation and disability impacted user attitudes towards AHs. We derive design dimensions for creating technological augmentations for a diverse and global audience.

Providing users with a haptic sensation of the hardness and softness of objects in virtual reality is an open challenge. While physical props and haptic devices help, their haptic properties do not allow for dynamic adjustments. To overcome this limitation, we present a novel technique for changing the perceived stiffness of objects based on a visuo-haptic illusion. We achieved this by manipulating the hands’ Control-to-Display (C/D) ratio in virtual reality while pressing down on an object with fixed stiffness. In the first study (N=12), we determine the detection thresholds of the illusion. Our results show that we can exploit a C/D ratio from 0.7 to 3.5 without user detection. In the second study (N=12), we analyze the illusion’s impact on the perceived stiffness. Our results show that participants perceive the objects to be up to 28.1% softer and 8.9% stiffer, allowing for various haptic applications in virtual reality.

Virtual reality experiences increasingly use physiological data for virtual environment adaptations to evaluate user experience and immersion. Previous research required complex medical-grade equipment to collect physiological data, limiting real-world applicability. To overcome this, we present SensCon for skin conductance and heart rate data acquisition. To identify the optimal sensor location in the controller, we conducted a first study investigating users' controller grasp behavior. In a second study, we evaluated the performance of SensCon against medical-grade devices in six scenarios regarding user experience and signal quality. Users subjectively preferred SensCon in terms of usability and user experience. Moreover, the signal quality evaluation showed satisfactory accuracy across static, dynamic, and cognitive scenarios. Therefore, SensCon reduces the complexity of capturing and adapting the environment via real-time physiological data. By open-sourcing SensCon, we enable researchers and practitioners to adapt their virtual reality environment effortlessly. Finally, we discuss possible use cases for virtual reality-embedded physiological sensing.

Racket sports offer an enjoyable form of physical activity and are fertile ground for interactive technologies supporting new players. Yet, current research has neglected its potential to support not only active players but also coaches in their training methods. To investigate how interactive technologies can support skill acquisition in training, we designed an Electrical Muscle Stimulation (EMS) system that helps maintain the ready position in crossminton. We compared the system with a vibrotactile solution in a user study, interviewing novice players and experienced coaches about their perception of the system. The system allowed coaches to effectively and immediately guide players to the ready position. An EMS-based feedback system for coaches can potentially reduce delay (physical and cognitive) for trainees, as stated by coaches. Our work contributes insights into designing systems that facilitate learning sports techniques using interactive feedback.

Mid-air haptics allow bare-hand tactile stimulation; however, it has a constrained workspace, making it unsuitable for room-scale haptics. We present a novel approach to rendering mid-air haptic sensations in a large rendering volume by turning a static array into a dynamic array following the user's hand. We used a 6DOF robot to drive a haptic ultrasound array over a large 3D space. Our system enables rendering room-scale mid-air experiences while preserving bare-hand interaction, thus, providing tangibility for virtual environments. To evaluate our approach, we performed three evaluations. First, we performed a technical system evaluation, showcasing the feasibility of such a system. Next, we conducted three psychophysical experiments, showing that the motion does not affect the user's perception with high likelihood. Lastly, we explored seven use cases that showcase our system's potential using a user study. We discuss challenges and opportunities in how large-scale mid-air haptics can contribute toward room-scale haptic feedback. Thus, with our system, we contribute to general haptic mid-air feedback on a large scale.

In the context of the 3DUI Contest promoted by the IEEE VR 2018, we propose 3D interaction techniques that address three distinct tasks in a virtual environment setup: climbing a ladder, controlling a quadcopter in a first-person view flight, and building a tower by stacking a series of objects. The interaction techniques were developed so the player, our 3D-athlete, has control over the events in each task, following metaphors that facilitate the use of the interface, and having status and spatial awareness supported by clear feedback cues. Thus, the player should be able to execute the tasks with precision and agility.