DigiTaps: eyes-free number entry on touchscreens with minimal audio feedback

Eyes-free input usually relies on audio feedback that can be difficult to hear in noisy environments. We present DigiTaps, an eyes-free number entry method for touchscreen devices that requires little auditory attention. To enter a digit, users tap or swipe anywhere on the screen with one, two, or three fingers. The 10 digits are encoded by combinations of these gestures that relate to the digits' semantics. For example, the digit 2 is input with a 2-finger tap. We conducted a longitudinal evaluation with 16 people and found that DigiTaps with no audio feedback was faster but less accurate than with audio feedback after every input. Throughout the study, participants entered numbers with no audio feedback at an average rate of 0.87 characters per second, with an uncorrected error rate of 5.63%.