Does it Press? Investigating the Efficacy of an Ultrasonic Haptic Button Interface for Non-Visual Driving Applications

Ultrasonic haptic (UH) feedback employs mid-air ultrasound waves detectable by the palm of the hand. This interface demonstrates a novel opportunity to utilize non-visual input and output (I/O) functionalities in interactive applications, such as vehicle controls that allow the user to keep their eyes on the road. However, more work is needed to evaluate the useability of such an interface. In this study, 16 blindfolded participants completed tasks involving finding and counting UH buttons, associating buttons with audio cues, learning spatial arrangements, and determining button states. Results showed that users were generally successful with 2–4 arranged buttons and could associate them with audio cues with an average accuracy of 77.1%. Participants were also able to comprehend button spatial arrangements with 77.8% accuracy and engage in reconstruction tasks to prove user understanding. These results signify the capability of UH feedback to have real-world I/O functionality and serve to guide future exploration in this area.