Touching the invisible: Localizing ultrasonic haptic cues

While mid-air gestures offer new possibilities to interact with or around devices, some situations, such as interacting with applications, playing games or navigating, may require visual attention to be focused on a main task. Ultrasonic haptic feedback can provide 3D spatial haptic cues that do not demand visual attention for these contexts. In this paper, we present an initial study of active exploration of ultrasonic haptic virtual points that investigates the spatial localization with and without the use of the visual modality. Our results show that, when providing haptic feedback giving the location of a widget, users perform 50% more accurately compared to providing visual feedback alone. When provided with a haptic location of a widget alone, users are more than 30% more accurate than when given a visual location. When aware of the location of the haptic feedback, active exploration decreased the minimum recommended widget size from 2cm² to 1cm² when compared to passive exploration from previous studies. Our results will allow designers to create better mid-air interactions using this new form of haptic feedback.