Pseudo-haptics and self-haptics for freehand mid-air text entry in VR

Despite the lack of haptic feedback, two-finger typing remains as a common freehand mid-air text entry method in VR. To compensate for this limitation, we investigated the effect of pseudo-haptics and thumb-to-finger pinch self-haptics. Three types of virtual keyboards were developed for comparison: a normal virtual keyboard without any haptic features, a pseudo-haptic keyboard providing a haptic illusion by adding pseudo-haptic features to the normal virtual keyboard, and a pinch keyboard providing passive self-haptic feedback when the index finger touches the thumb to type bubble-shaped keys. A follow-up user study was conducted on the three keyboards to measure typing performance, perceived workload, and user experience. The results showed that the pseudo-haptic and pinch keyboards were comparable to the normal one in typing performance and workload, but beneficial in user experience and preference. The findings suggest that pseudo-haptics and self-haptics could achieve experiential benefits in VR text entry without obtrusive extra devices.