ThermalTexture: Temperature-Integrated Surface Rendering Using Thermal Referral Induced by Texture Slip-Feedback.

Thermal-vibration feedback has been reported to elicit the thermal referral phenomenon, offering new possibilities for enhancing user experience. Yet, little research has explored whether thermal referral occurs in the presence of texture-slip feedback. To address this, we developed a custom haptic device capable of delivering integrated thermal and slip feedback to the middle and distal phalanges of an index finger. We primarily estimated the thermal referral occurrence under passive and active touch conditions across two different perceptual experiments, while each further examined its impact on texture perceptions and user experiences (UX). In Perceptual Experiment 1 (passive), we observed the highest occurrence of thermal referral at 40 $^{\circ }\mathrm{C}$ (0.86 on a 0-1 scale), and found that referral increased the median of perceived roughness from 43.5 to 60 on a 0-100 scale. In Perceptual Experiment 2 (active), the kinesthetic cues significantly enhanced thermal referral, with the occurrence probability at 24 $^{\circ }\mathrm{C}$ increasing to 0.86 compared to 0.51 (0-1 scale) in the first study. In addition, high UX ratings demonstrated the applicability of our device to temperature-integrated virtual texture interactions. Our findings expand the scope of thermal referral and highlight the potential for enabling VR users to interact with virtual surfaces that provide temperature cues.