HCI Deep Dives

Virtual body extensions like wings or tails offer exciting new experiences in VR, but using them naturally—especially parts you can't see, like a tail—requires proprioceptive feedback to sense position and force without relying on vision. This paper introduces the "Imaginary Joint," a novel approach that uses skin-stretch feedback at the interface between your body and a virtual extension. A wearable device stretches and compresses...

Electro-tactile interfaces—which deliver tactile sensations through electrical stimulation of skin nerves—offer unique advantages like fast response times, thin flexible form factors, and the ability to simulate textures, softness, and even coldness. But designing them has been notoriously difficult, requiring deep electronics expertise and custom hardware. eTactileKit changes that. This open-source toolkit provides end-to-end supp...

What happens when you watch yourself perform in VR—and then have to critique that performance? This study explored self-reflection in motor skill learning using a Karate training task. Participants were embodied as a "trainer" avatar and asked to give verbal feedback on a "trainee"—which was either their own 3D-scanned appearance or a stranger, performing either their own recorded movements or an expert's. The results revealed a ps...

Can fake heartbeat sounds trick your body into relaxing? This system generates pseudo-heartbeat audio at rates slightly slower than your actual heart rate to induce calm and support meditation. Using a contactless radar sensor to detect real heartbeats, it creates slower auditory feedback (10-30% below actual BPM). Tested with 120 participants at SIGGRAPH Asia 2024, results showed that hearing slower heartbeats made people feel the...

Learning to identify musical pitch intervals usually requires tedious rote practice. Purrfect Pitch offers a new approach: a wearable haptic vest that translates sound into touch. When users hear two musical notes, they simultaneously feel vibrations at corresponding vertical positions on their back—leveraging our natural "high/low" pitch metaphor. In a study with 18 participants, those using the audio-haptic system identified inte...

Processing high-resolution video with AI requires massive computational resources. GazeLLM offers an elegant solution inspired by human vision: use eye-tracking to focus only on what matters. By cropping first-person video to a small region around the user's gaze point, the system reduces pixel input to just one-tenth while achieving task comprehension equal to or better than full-resolution video. User evaluations across six real-...

Traditional quadrotor drones pose safety concerns with their spinning blades. Cuddle-Fish takes a different approach: a helium-filled soft robot with bio-inspired flapping wings that's safe enough to touch, hug, and interact with physically. In testing with 24 participants, people spontaneously engaged in affective behaviors like patting, stroking, and even hugging the robot. Users reported positive emotional responses and felt saf...

Our bodies experience a wide variety of kinesthetic forces as we go about our daily lives, including the weight of held objects, contact with surfaces, gravitational loads, and acceleration and centripetal forces while driving, to name just a few. These forces are crucial to realism, yet simply cannot be rendered with today’s consumer haptic suits, which primarily rely on arrays of vibration actuators built into vests. Rigid exoske...

Xiaru Meng, Yulan Ju, Christopher Changmok Kim, Yan He, Giulia Barbareschi, Kouta Minamizawa, Kai Kunze, and Matthias Hoppe. 2025. A Placebo Concert: The Placebo Effect for Visualization of Physiological Audience Data during Experience Recreation in Virtual Reality. In Proceedings of the 2025 CHI Conference on Human Factors in Computing Systems (CHI '25). Association for Computing Machinery, New York, NY, USA, Article 807, 1–16. ht...

Perceiving and altering the sensation of internal physiological states, such as heartbeats, is key for biofeedback and interoception. Yet, wearable devices used for this purpose can feel intrusive and typically fail to deliver stimuli aligned with the heart’s location in the chest. To address this, we introduce Heartbeat Resonance, which uses low-frequency sound waves to create non-contact haptic sensations in the chest cavity, mim...

To enhance focused eating and dining socialization, previous Human-Food Interaction research has indicated that external devices can support these dining objectives and immersion. However, methods that focus on the food itself and the diners themselves have remained underdeveloped. In this study, we integrated biofeedback with food, utilizing diners’ heart rates as a source of the food’s appearance to promote focused eating and din...

When several individuals collaborate on a shared task, their brain activities often synchronize. This phenomenon, known as Inter-brain Synchronization (IBS), is notable for inducing prosocial outcomes such as enhanced interpersonal feelings, including closeness, trust, empathy, and more. Further strengthening the IBS with the aid of external feedback would be beneficial for scenarios where those prosocial feelings play a vital role...

Yulan Ju, Xiaru Meng, Harunobu Taguchi, Tamil Selvan Gunasekaran, Matthias Hoppe, Hironori Ishikawa, Yoshihiro Tanaka, Yun Suen Pai, and Kouta Minamizawa. 2025. Haptic Empathy: Investigating Individual Differences in Affective Haptic Communications. In Proceedings of the 2025 CHI Conference on Human Factors in Computing Systems (CHI '25). Association for Computing Machinery, New York, NY, USA, Article 501, 1–25. https://doi.org/10....

Recently, digital displays such as liquid crystal displays and projectors have enable...

Hu, Yuhan, Peide Huang, Mouli Sivapurapu, and Jian Zhang. "ELEGNT: Expressive and Functional Movement Design for Non-anthropomorphic Robot." arXiv preprint arXiv:2501.12493(2025).

https://arxiv.org/abs/2501.12493

Nonverbal behaviors such as posture, gestures, and gaze are essential for conveying internal states, both consciously and unconsciously, in human interaction. For robots to interac...

K. Brandstätter, B. J. Congdon and A. Steed, "Do you read me? (E)motion Legibility of Virtual Reality Character Representations," 2024 IEEE International Symposium on Mixed and Augmented Reality (ISMAR), Bellevue, WA, USA, 2024, pp. 299-308, doi: 10.1109/ISMAR62088.2024.00044.

We compared the body movements of five virtual reality (VR) avatar representations in a user study (N=53) to ascertain how well these representations could...

The Oscar best picture winning movie CODA has helped introduce Deaf culture to many in the hearing community. The capital "D" in Deaf is used when referring to the Deaf culture, whereas small "d" deaf refers to the medical condition. In the Deaf community, sign language is used to communicate, and sign has a rich history in film, the arts, and education. Learning about the Deaf culture in the United States and the importance of Ame...

J. Lee et al., "Whirling Interface: Hand-based Motion Matching Selection for Small Target on XR Displays," 2024 IEEE International Symposium on Mixed and Augmented Reality (ISMAR), Bellevue, WA, USA, 2024, pp. 319-328, doi: 10.1109/ISMAR62088.2024.00046.

We introduce “Whirling Interface,” a selection method for XR displays using bare-hand motion matching gestures as an input technique. We extend the motion matching input method, by...

Z. Chang et al., "Perceived Empathy in Mixed Reality: Assessing the Impact of Empathic Agents’ Awareness of User Physiological States," 2024 IEEE International Symposium on Mixed and Augmented Reality (ISMAR), Bellevue, WA, USA, 2024, pp. 406-415, doi: 10.1109/ISMAR62088.2024.00055. https://doi.org/10.1109/ISMAR62088.2024.00055

In human-agent interaction, establishing trust and a social bond with the agent is crucial to improving c...