Electrotactile Improves Thermal Referral
For VR and haptics researchers, this work improves thermal feedback by enabling more realistic non-contact thermal sensations, though it is an incremental improvement over existing vibrotactile methods.
The authors propose replacing vibrotactile with electrotactile cues for thermal referral, addressing limitations in cold sensation referral and reducing unwanted tactile buzz. In user studies (N=22 and N=20), electrotactile increased cold referral rate, improved thermal perception while minimizing tactile interference, and enhanced realism in VR thermal scenarios.
Thermal referral enables thermal sensations in locations lacking thermal actuators--this is achieved using vibrotactile actuators to redirect a nearby thermal sensation to where a tactile sensation is applied. However, we found that its reliance on vibration introduces critical limitations: it struggles to produce cold referral, and the inherent strong tactile "buzz" makes it unsuitable for simulating non-contact thermal events, such as the chill of an open freezer in VR (in contrast to contact-based thermal events like touching the freezer's cold handle). To improve this, we propose a shift from vibrotactile to electrotactile-based thermal referral. We evaluated in two user studies--a psychophysics experiment (N=22) and a VR deployment (N=20)--where we contrasted electrotactile with vibrotactile-based thermal referral. Our results reveal key advantages of the electrotactile based thermal referral: (1) increases the referral rate for cold sensations; (2) increases thermal perception while minimizing tactile; and (3) improves realism across a range of VR thermal scenarios, specifically distinguishing between contact-based and non-contact thermal events. Finally, we provide design guidelines for choosing tactile cues to create immersive multimodal thermal experiences in VR.