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.

Mid-air tactile stimulation using ultrasonics has been used in a variety of human computer interfaces in the form of prototypes as well as products. When generating these tactile patterns with mid-air tactile ultrasonic displays, the common approach has been to sample the patterns using the hardware update rate capabilities to their full extent. In the current study we show that the hardware update rate can impact perception, but unexpectedly we find that higher update rates do not improve pattern perception. In a first user study, we highlight the effect of update rate on the perceived strength of a pattern, especially for patterns rendered at slow rate of less than 10 Hz. In a second user study, we identify the evolution of the optimal update rate according to variations in pattern size. Our main results show that update rate should be designated as additional parameter for tactile patterns. We also discuss how the relationships we defined in the current study can be implemented into designer tools so that designers remain oblivious to this additional complexity.

Major virtual reality (VR) companies are trying to enhance the sense of immersion in virtual environments by implementing haptic feedback in their systems (e.g., Oculus Touch). It is known that tactile stimulation adds realism to a virtual environment. In addition, when users are not limited by wearing any attachments (e.g., gloves), it is even possible to create more immersive experiences. Mid-air haptic technology provides contactless haptic feedback and offers the potential for creating such immersive VR experiences. However, one of the limitations of mid-air haptics resides in the need for freehand tracking systems (e.g., Leap Motion) to deliver tactile feedback to the user's hand. These tracking systems are not accurate, limiting designers capability of delivering spatially precise tactile stimulation. Here, we investigated an alternative way to convey incongruent visual-tactile stimulation that can be used to create the illusion of a congruent visual-tactile experience, while participants experience the phenomenon of the rubber hand illusion in VR.

Current attempts to render touch in multimedia technology still represents a challenge. Touch is indeed a complex system and there are many aspects to take into account when trying to rendering it (e.g. the compliance of an object, its weight, orientation, geometric properties and forces on the skin). This is especially true for VR, where touch is an important factor to achieve the embodiment in virtual environments. Recently, new tactile technology has been developed: the mid-air devices, capable of delivering tactile feedback without entering in contact with the skin. One of the contributions of the doctoral research described in this paper is to overcome design challenges and create immersive experiences by applying psychological principles and paradigms, exploiting the advantages of the mid-air technology. We designed possible embodied interaction scenarios in mid-air and physical touch. Findings from these research point to opportunities for designing new immersive experiences. Future work will involve different parts of the body and different tactile properties (e.g. thermal stimulation).

Apparent tactile motion has been shown to occur across many contiguous part of the body, such as fingers, forearms, and back. A recent study demonstrated the possibility of eliciting the illusion of movement from one hand to the other when interconnected by a tablet. In this paper we explore intermanual apparent tactile motion without any object between them. In a series of psychophysical experiments we determine the control space for generating smooth and consistent motion, using two vibrating handles which we refer to as the Hand-to-Hand vibrotactile device. In a first experiment we investigated the occurrence of the phenomenon (i.e., movement illusion) and the generation of a perceptive model. In a second experiment, based on those results, we investigated the effect of hand postures on the illusion. Finally, in a third experiment we explored two visuo-tactile matching tasks in a multimodal VR setting. Our results can be applied in VR applications with intermanual tactile interactions.