Ultrasonic mid-air haptics (UMH) offers a novel way to modulate affective responses through contactless, biosignal features inspired haptics (i.e., BioHaptics). Yet, the effects of different BioHaptics on affective responses of emotions experienced during video-watching context are unclear, limiting the flexible emotion modulation and broader use of UMH as a natural affective design channel in enhancing everyday media consumption. This paper explores how BioHaptics encoded from different biosignal features (e.g., heart rate (HR), heart rate variability (HRV), and respiration amplitude (RA)) impact emotions in video-watching contexts. In two experiments with 70 participants, we assessed affective responses while adding three BioHaptics during the video-watching processes. Results showed that HR and RA haptics promoted RA and HRV, with potential increments in emotional pleasantness and regulation; HRV haptics lowered HR, leading to calmer responses. This research offers implications and recommendations for emotion modulation through UMH and advances the design of emotionally engaging multisensory feedback.

Perceived Continuity CRE f) FE STM CRE FE STM a) 1 2 3 3 4 c) b) d) Figure 1: a) Different sensitivity areas across the hand overlaid with pacinian receptors (dots).We create tactile shapes at low (c) and high (b) sensitivity areas, as well as across areas (d and e), comparing their perceived intensity and continuity when using spatiotemporal modulation (STM) and tactile illusions (funneling effect (FE) and cutaneous rabbit effect (CRE) ) (f).

With perpetually stressful lives, people are prompted to consider slowing down through mindfulness meditation. We extend HCI research beyond its pre-existing focus on interaction-intensive meditation technologies, to focus simply on whether one’s sense of touch can facilitate meditation. We capitalise on the touchless nature of mid-air haptics by rendering subtle sensations on the palm during meditation, using one design derived from pilot testing. In a novel and exploratory between-subjects study, we compare audio versus audio-haptic guidance in adult novices’ mindfulness meditation, through a mixed methods approach which combines standardised questionnaires with micro-phenomenological interviews ( n =10 per group). Interestingly, mid-air haptics quantitatively increased both hindrance and relaxation, which appears conflicting but is actually complementary when considered together with qualitative analysis. Specifically, mid-air haptics initially distracted participants but eventually facilitated mindfulness through three processes (embodied metaphor, breath alignment, and meditative grounding), though this requires further validation. We reflect on the need for future work exploring an integrated, multimodal meditation experience.

Sensory perception and emotional evaluation of a stimulus are deeply interconnected with sensory awareness and attention. Mindfulness meditation is a well-established tool for enhancing attention and awareness, but can this heightened awareness influence how we perceive and emotionally evaluate tactile stimuli? In this work, we investigate how mindfulness meditation influences sensory perception and emotional evaluation of gentle stroking stimuli delivered to the forearm using ultrasound-based mid-air haptics, providing tactile sensations without direct skin contact. Two studies were conducted to assess the effects of mindfulness on (1) perceived intensity, confidence, valence, and arousal in response to simple linear strokes and (2) pattern recognition and emotional evaluation of complex mid-air haptic patterns. Our findings suggest that mindfulness enhances perceived intensity, confidence, and valence ratings, but does not influence arousal ratings. Pattern recognition was challenging for the participants on the forearm leading to poor accuracy but mindfulness still enhances the recognition. These findings highlight the potential of mindfulness-enhanced haptic interactions in digital wellbeing and virtual environments. Future research should explore long-term mindfulness training, multi-sensory integration, and adaptive haptic systems to further optimize affective haptic experiences.

Multi-point STM offers a great range of parameters (i.e., drawing frequency, number of points) to produce different tactile sensations. However, existing studies offer limited insight on the effects of these parameters, and ignore their effect on the physical stimuli delivered, limiting effective haptic design. We propose a two-stage model to predict response to multi-point STM. The first stage predicts physical stimulus properties with 7.8% error, while the second stage predicts mean and spread of perceived intensity with 8.0 % and 8.8% error. We report 3 studies conducted to derive this model: one to characterize physical stimuli, another one measuring user perceptual thresholds, and a third one measuring user’s perceptual response to multi-point STM. Besides, we characterize 4 effects that influence device performance, confirm if previous effects reported are due to physical or perceptual effects (or both) and derive recommendations for manufacturers, haptic designers and HCI researchers.

The rapid development of touchless systems has introduced many innovations in social interaction scenarios in recent years. People now can interact with touchless systems in social applications that are aimed to be used in everyday situations in the future. This accelerated development makes us ask, what will the next generation of touchless systems be like? How can we responsibly develop new touchless technologies in the future? To answer the first question, we brought together 20 experts to ideate, speculate, and evaluate possible touchless applications for social interactions. A total of 48 ideas were generated from two consecutive workshops. Then, to answer the second question, we critically analyzed those ideas through a thematic analysis using a responsible innovation (RI) framework, and identified key ethical considerations to guide developers, practitioners when designing future touchless systems. We argue that the social scenarios described, and the RI framework proposed in this paper are a useful starting point for responsibly designing the next generation of touchless systems.

Spatiotemporal modulation (STM) is used to render tactile patterns with ultrasound arrays. Previous research only explored the effects of single-point STM parameters, such as drawing speed (Vd). Here we explore the effects of multi-point STM on both perceptual (intensity) and emotional (valence/arousal) responses. This introduces a new control parameter for STM - the number of focal points (Nfp) – on top of conventional STM parameter (Vd). Our results from a study with 30 participants showed a negative effect of Nfp on perceived intensity and arousal, but no significant effects on valence. We also found the effects of Vd still aligned with prior results for single-point, even when different Nfp were used, suggesting that effects observed from single-point also apply to multi-point STM. We finally derive recommendations, such as using single-point STM to produce stimuli with higher intensity and/or arousal, or using multi-point STM for milder and more relaxing (less arousing) experiences.

As we constantly seek to improve and expand upon the capabilities of technology, we frequently wonder whether we use technology to its fullest extent. Studies indicate that increasing our awareness and mindfulness of our senses may lead to a journey of unexplored experiences. In this paper, we focus on the perception of mid-air haptics stimuli and whether it can be improved through mindfulness meditation. We have conducted an experiment with 22 participants given the task to recognize digits 0 to 9 drawn on their palms using a mid-air haptic device under two conditions - with and without prior mindfulness meditation. Results show that for frequencies targeting both Meissner (40 Hz) and Pacinian (200 Hz) receptors, meditation significantly improves performance of the participants, as well as increases their confidence. This suggests that including a short meditation step in haptic user interfaces could lead to improved system performance and user satisfaction.

Considering 3D interactions in Virtual-Reality (VR), it is critical to study how visual awareness of real hands influences users scaled interaction performance in different VR environments. We used Fitts’s law to analyze user performance with five different Control-Display (CD) ratios (1:1 to 1:5). Fifteen participants performed a 3D selection task in three different setups: Head-Mounted Display (HMD), and two variations of the Active One-walled 3D Projection (AOP), with and without visual awareness of the real hand (AOP-A and AOP-B, respectively). The results show that the throughput of AOP-B is significantly higher than that of the AOP-A and HMD (p = .00001 and 0.0002, respectively) which suggests the existence of a conflict between the kinesthetic and visual real-hand movements, which we term as Virtual Kinesthetic Conflict (VKC). To reduce VKC during scaled movements, tasks should be designed such that the visual awareness of the real hand is avoided.