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 control the temperature of materials in everyday interactions, recognizing temperature’s important influence on our bodies, minds, and experiences. However, thermal feedback is an under-explored modality in human-computer interaction partly due to its limited temporal (slow) and spatial (small-area and non-moving) capabilities. We introduce hydroptical thermal feedback, a spatial thermal feedback method that works by applying visible lights on body parts in water. Through physical measurements and psychophysical experiments, our results show: (1) Humans perceive thermal sensations when visible lights are cast on the skin under water, and perceived warmth is greater for lights with shorter wavelengths, (2) temporal capabilities, (3) apparent motion (spatial) of warmth and coolness sensations, and (4) hydroptical thermal feedback can support the perceptual illusion that the water itself is warmer. We propose applications, including virtual reality (VR), shared water experiences, and therapies. Overall, this paper contributes hydroptical thermal feedback as a novel method, empirical results demonstrating its unique capabilities, proposed applications, and design recommendations for using hydroptical thermal feedback. Our method introduces controlled, spatial thermal perceptions to water experiences.

The objective of this study was to develop and evaluate a thermal display that assists in object identification in virtual environments by simulating the thermal cues associated with making contact with materials with different thermal properties. The thermal display was developed based on a semi-infinite body model. Three experiments were conducted to evaluate the performance of the display. The first experiment compared the ability of subjects' to identify various materials, which were presented physically or simulated with the thermal display. The second experiment examined the capacity of subjects to discriminate between a real and simulated material based on thermal cues. In the third experiment, the changes in skin temperature that occurred when making contact with real and simulated materials were measured to evaluate how these compare to theoretical predictions. The results indicated that there was no significant difference in material identification and discrimination when subjects were presented with real or simulated materials. The changes in skin temperature were comparable for real and simulated materials and were related to the contact coefficient of the material palpated, consistent with the semi-infinite body model. These findings suggest that a thermal display is capable of facilitating object recognition when visual cues are limited.