Social touch is a rich channel of human communication, conveying emotion, intent, and meaning embedded in context. Yet most HCI studies treat touch in isolation, overlooking the layered subtleties that shape interpretation. We present a contextual analysis of 5,016 social touch events, grounded in a large collection of annotated scenes from films, dramas, and documentaries. Using a computer vision pipeline, we segmented touch events from video and annotated them across dimensions, including who is involved, how the gesture is performed, where on the body it occurs, and the cultural backdrop. Our analysis shows that identical gestures can convey distinct meanings depending on body location, relationship type, and context. Similar intentions—like comfort, encouragement, or dominance—may be expressed through different gestures or locations, shaped by relational dynamics, cultural norms, and public or private settings. These insights inform the design of socially aware touch technologies, including avatars, social agents, and mediated communication systems.

Simulating wetness in interactive systems is challenging due to the lack of dedicated hygroreceptors in human skin and the complexity of delivering physical moisture. We introduce Moisture Transfer, a perceptual wetness illusion in which users feel moisture at a dry site when cold and wet stimuli are applied nearby. This illusion arises from the brain’s spatial integration of thermal and tactile cues, offering a new pathway to render wetness without direct contact. We investigate this illusion by establishing it with a single finger and show that thermal congruence enhances perceived wetness. We then explored its spatial extent across five fingers, revealing lateral transfer of wetness. Finally, we applied these findings to create a proof-of-concept VR interface that evokes full-hand wetness using minimal actuation. We conclude with design implications for XR and wearable systems and outline future work exploring body-wide wetness illusions and multisensory integration.

Thermal masking, a vibration-induced illusion in which concurrent tactile input induces a vivid thermal sensation at the tactile site, is a promising mechanism for wearable interfaces and extended reality because it can deliver rich thermal feedback with minimal hardware. While prior work has examined this phenomenon on limited body parts, its expression across the full body remains under exploration. We present four studies mapping thermal masking across eight regions: head, face, neck, arms, hands, torso, legs, and feet. Results show that masking strength is location-dependent, producing perceptual patterns that align primarily with somatosensory pathways rather than proximity. On smaller regions such as the fingers, masking was localized, while on larger areas such as the torso and neck, it extended more broadly. Dorsal–ventral and inter-body tests revealed viable pairings and perceptual boundaries. These findings provide the first comprehensive atlas of body-wide thermal masking, advancing understanding and guiding efficient thermal–tactile interface design.

Figure 1: UltraEdit with blob interaction.A user is pulling a blob out of a 3D object, editing it, then releasing it.

Low-latency multimodal feedback is essential for maintaining a high-quality user experience in VR; however, unpredictable network conditions can introduce latency that negatively impacts user experience. This work investigates how users perceive multimodal haptic feedback—specifically thermal (hot/cold) and tactile stimuli—and how latency in such feedback affects user experience. We first measured users’ response times for thermal, tactile, and combined thermal-tactile stimuli. Subsequently, we conducted a psychophysical study to identify delay thresholds for each modality by examining temporal congruency between visual and haptic cues. We designed a haptic delay network simulator to emulate a realistic network environment. Results highlighted that combined thermal-tactile feedback has higher latency tolerance than thermal-only feedback, indicating that multimodal integration can buffer the negative effects of latency. Using these thresholds, we designed controlled latency conditions and assessed user experience. Based on our findings, we propose design recommendations for haptic data transmission in networked VR systems.

This paper reports on a thermal illusion called thermal masking. Thermal masking is a phenomenon induced by thermal referral to completely mask the original thermal sensation, providing thermal sensation only at the tactile site. Three experiments are conducted using thermal and vibrotactile actuators to investigate the nature of thermal masking on human arms. The first experiment investigates the effects of different temperatures on masking. The results show a higher percentage of thermal masking occurs in warm than hot or cold conditions. The second experiment examines how far the thermal masking can be perceived. The results show that masking can reach up to 24 cm from the thermal site. The third experiment explores the interaction space by placing the tactile actuators on the opposite side of the thermal actuator. The results confirm that thermal masking can reach the other side of the arm, and the performance was higher in warm conditions.

This study explores the impact of combining multiple senses on how people perceive wetness in mid-air. We examine how factors like temperature, pressure, and visual stimuli influence the illusion of wetness on users’ palms. The first user study examines these effects and the complex relationships between these variables. The findings suggest that increased temperature and pressure increase the likelihood of perceiving wetness. Interestingly, we note the influence of visual scene content on wetness perception. This leads to our second user study, which investigates how visual context impacts wetness perception. The results demonstrate a strong link between visual content and wetness perception, offering valuable insights for designing immersive virtual reality experiences that enhance sensory perception.

We present a novel approach to render thermal and tactile feedback to the palm and fingertips through thermal and tactile integration. Our approach minimizes the obstruction of the palm and inner side of the fingers and enables virtual object manipulation while providing localized and global thermal feedback. By leveraging thermal actuators positioned strategically on the outer palm and back of the fingers in interplay with tactile actuators, our approach exploits thermal referral and tactile masking phenomena. Through a series of user studies, we validate the perception of localized thermal sensations across the palm and fingers, showcasing the ability to generate diverse thermal patterns. Furthermore, we demonstrate the efficacy of our approach in VR applications, replicating diverse thermal interactions with virtual objects. This work represents significant progress in thermal interactions within VR, offering enhanced sensory immersion at an optimal energy cost.

This study presents a novel method for creating moving thermal sensations by integrating the thermal referral illusion with tactile motion. Conducted through three experiments on human forearms, the first experiment examined the impact of temperature and thermal actuator placement on perceived thermal motion, finding the clearest perception with a centrally positioned actuator under both hot and cold conditions. The second experiment identified the speed thresholds of perceived thermal motion, revealing a wider detectable range in hot conditions (1.8 cm/s to 9.5cm/s) compared to cold conditions (2.4cm/s to 5.0cm/s). Finally, we integrated our approach into virtual reality (VR) to assess its feasibility through two interaction scenarios. Our results shed light on the comprehension of thermal perception and its integration with tactile cues, promising significant advancements in incorporating thermal motion into diverse thermal interfaces for immersive VR experiences.

This paper presents a fabric-based thermal display of a polyester fabric material combined with thermally-conductive materials using an ultrasound haptic display. We first empirically test the thermal generation process in five fabric materials by applying 40 kHz ultrasonic waves to the fabric materials. We also examine their thermal characteristics by applying different frequencies and amplitudes of ultrasonic cues. We show that polyester demonstrates the best thermal performance. We then combine it with thermally-conductive materials, including copper and aluminum, and compare them with the fabric-only condition. Two user studies show that our approach of combining a fabric material with copper and aluminum outperforms fabric-only conditions in thermal perception and thermal level identification. We integrate polyester with aluminum into a glove to explore the use cases in VR and share our findings, insights, limitations, and future works.

This paper investigates the effects of thermal referral and tactile masking illusions to achieve localized thermal feedback on the upper body. Two experiments are conducted. The first experiment uses a 2D array of sixteen vibrotactile actuators $(4\times 4)$ with four thermal actuators to explore the thermal distribution on the user's back. A combination of thermal and tactile sensations is delivered to establish the distributions of thermal referral illusions with different numbers of vibrotactile cues. The result confirms that localized thermal feedback can be achieved through cross-modal thermo-tactile interaction on the user's back of the body. The second experiment is conducted to validate our approach by comparing it with thermal-only conditions with an equal and higher number of thermal actuators in VR. The results show that our thermal referral with a tactile masking approach with a lesser number of thermal actuators achieves higher response time and better location accuracy than thermal-only conditions. Our findings can contribute to thermal-based wearable design to achieve greater user performance and experiences.

We examine mid-air typing data collected from touch typists to evaluate the features and classification models for recognizing finger stroke. A large number of finger movement traces have been collected using finger motion capture systems, labeled into individual finger strokes, and classified into several key features. We test finger kinematic features, including 3D position, velocity, acceleration, and temporal features, including previous fingers and keys. Based on this analysis, we assess the performance of various classifiers, including Naive Bayes, Random Forest, Support Vector Machines, and Deep Neural Networks, in terms of the accuracy for correctly classifying the keystroke. We finally incorporate a linguistic heuristic to explore the effectiveness of the character prediction model and improve the total accuracy.

This paper presents a new way of data abstraction for visual and haptic representations in immersive analytics using a mid-air haptic display. Visual and haptic abstraction is proposed to transform raw data (wind tunnel data) into another form of data for effective visual and haptic data mapping. Three main features are extracted: (i) Magnitude of Velocity, (ii) Recirculation Region, and (iii) Vorticity. For each feature, visual and haptic abstractions are defined based on data characterization and data reduction. A preliminary study shows a promising direction toward multimodal data interaction in immersive analytics.

This paper presents MetaTwin, a collaborative Metaverse platform that supports one-to-one spatiotemporal synchrony between physical and virtual spaces. The users can interact with other users and surrounding IoT devices without being tied to physical spaces. Resource sharing is implemented to allow users to share media, including presentation slides and music. We deploy MetaTwin in two different network environments (i.e., within the US, Korea-US international) and summarize users’ feedback about the experience.

In this paper, we investigate the effects of mid-air haptics in interactive 3D data visualization. We build an interactive 3D data visualization tool that adapts hand gestures and mid-air haptics to provide tangible interaction in VR using ultrasound haptic feedback on 3D data visualization. We consider two types of 3D visualization datasets and provide different data encoding methods for haptic representations. Two user experiments are conducted to evaluate the effectiveness of our approach. The first experimental results show that adding a mid-air haptic modality can be beneficial regardless of noise conditions and useful for handling occlusion or discerning density and volume information. The second experiment results further show the strengths and weaknesses of direct touch and indirect touch modes. Our findings can shed light on designing and implementing a tangible interaction on 3D data visualization with mid-air haptic feedback.

This paper presents a mid-air thermo-tactile feedback system using an ultrasound haptic display. We design a proof-of-concept thermo-tactile feedback system with an open-top chamber, heat modules, and an ultrasound display. Our approach is to provide heated airflow along the path to the focused pressure point created from the ultrasound display to generate thermal and vibrotactile cues in mid-air simultaneously. We confirm that our system can generate the thermo-tactile stimuli up to 54.2°C with 3.43 mN when the ultrasonic haptic signal was set to 100 Hz with a 12 mm radius of the cue size. We also confirm that our system can provide a stable temperature (mean error=0.25%). We measure the warm detection threshold (WDT) and the heat-pain detection threshold (HPDT). The results show that the mean WDT was 32.8°C (SD=1.12), and the mean HPDT was 44.6°C (SD=1.64), which are consistent with the contact-based thermal thresholds. We also found that the accuracy of haptic pattern identification is similar for non-thermal (98.1%) and thermal conditions (97.2%), showing a non-significant effect of high temperature. We finally confirmed that thermo-tactile feedback further enhances the user experiences.

We empirically explore fundamental requirements for achieving VR in-air typing by observing the unconstrained eyes-free in-air typing of touch typists. We show that unconstrained typing movements differ substantively from previously observed constrained in-air typing movements and introduce a novel binary categorization of typing strategies: typists who use finger movements alone (FINGER) and those who combine finger movement with gross hand movement (HAND). We examine properties of finger kinematics, correlated movement of fingers, interrelation in consecutive key-strokes, and 3D distribution of key-stroke movements. We report that, compared to constrained typing, unconstrained typing generates shorter (49 mm) and faster (764 mm/s) key-strokes with a high correlation of finger movement and that the HAND strategy group exhibits more dynamic key-strokes. We discuss how these findings can inform the design of future in-air typing systems.

We propose a data-driven method for realistic texture rendering on an electrovibration display. To compensate the nonlinear dynamics of an electrovibration display, we use nonlinear autoregressive with external input (NARX) neural networks as an inverse dynamics model of an electrovibration display. The neural networks are trained with lateral forces resulting from actuating the display with a pseudo-random binary signal (PRBS). The lateral forces collected from the textured surface with various scanning velocities and normal forces are fed into the neural network to generate the actuation signal for the display. For arbitrary scanning velocity and normal force, we apply the two-step interpolation scheme between the closest neighbors in the velocity-force grid.

Haptic cues are a valuable feedback mechanism for smart glasses. Prior work has shown how they can support navigation, deliver notifications and cue targets. However, a focus on actuation technologies such as mechanical tactors or fans has restricted the scope of research to a small number of cues presented at fixed locations. To move beyond this limitation, we explore perception of in-air ultrasonic haptic cues on the face. We present two studies examining the fundamental properties of localization, duration and movement perception on three facial sites suitable for use with glasses: the cheek, the center of the forehead, and above the eyebrow. The center of the forehead led to optimal performance with a localization error of 3.77mm and accurate duration (80%) and movement perception (87%). We apply these findings in a study delivering eight different ultrasonic notifications and report mean recognition rates of up to 92.4% (peak: 98.6%). We close with design recommendations for ultrasonic haptic cues on the face.

We investigate the effect of information content in sensory feedback on typing performance using a flat keyboard. We build a flat keyboard apparatus with haptic and auditory keyclick feedback. We evaluate and compare typing performance with key-press confirmation and key-correctness information through sensory feedback. Twelve participants are asked to touch-type a number of randomly selected phrases under various combinations of visual, auditory and haptic sensory feedback conditions. The results show that typing speed is not significantly affected by the information content in sensory feedback, but the uncorrected error rate is significantly lower when key-correctness information is available. The results also show that key-correctness information leads to more corrected errors and lowers typing efficiency. Our findings are useful for developing flat keyboards with assistive information through sensory feedback. Our study is the first step towards improving typing performance on flat keyboards by delivering more advanced and comprehensive assistive information beyond the visual channel.

In this paper, we conduct a detailed study of the YouTube CDN with a view to understanding the mechanisms and policies used to determine which data centers users download video from. Our analysis is conducted using week-long datasets simultaneously collected from the edge of five networks - two university campuses and three ISP networks - located in three different countries. We employ state-of-the-art delay-based geolocation techniques to find the geographical location of YouTube servers. A unique aspect of our work is that we perform our analysis on groups of related YouTube flows. This enables us to infer key aspects of the system design that would be difficult to glean by considering individual flows in isolation. Our results reveal that while the RTT between users and data centers plays a role in the video server selection process, a variety of other factors may influence this selection including load-balancing, diurnal effects, variations across DNS servers within a network, limited availability of rarely accessed video, and the need to alleviate hot-spots that may arise due to popular video content.

In this paper, we propose the seamless video transmission scheme over wireless LANs during fast handover in Mobile IPv6. In fact, a mobile node cannot receive the IP packets during handover. A number of extensions to fast handover for mobile IPv6 have been introduced to recover its weakness. Fast handover algorithm in mobile IPv6 allows the new access router in the adjacent cell to pre-buffer the data packets of a mobile node to prevent packet loss. In a mobile communication environment, however, transmission of multimedia data should consider the realtimeliness of the data. We focus on the multimedia data delivery during fast handover in mobile IPv6 environment

In this work, we develop a hierarchical load testing architecture using large scale virtual clients to reduce the testing time and ensure the stability of the server for distributed applications. It explicitly secures the stability of the servers for networked virtual environment and at the same time, it elaborately generates actual loads for testing the performance of the servers. Our agent based load testing architecture provides variety of interactions of virtual entities in the virtual worlds to perform realistic simulations. Simulation results illustrate that our proposed architecture ensures the stability and capacity of the servers for both massively multiplayer online games and peer-to-peer network games