A Rotary Dial for Gaze-based PIN Entry

We detail the design and evaluation of a rotary interface for gaze-based PIN code entry. Interface design promotes equal distance between PIN numerals, leading to a circular layout resulting in the choice of a rotary telephone dial metaphor. The rotary's speed advantage over the traditional grid-based (e.g., keypad) design is derived from its elimination of dwell time for gaze-based numeral selection, relying instead on a weighted voting scheme of numerals whose boundaries are crossed by the streaming (smoothed) gaze points. Screen center-bias is exploited by requiring users to transition to and from the center to the rotary numerals, in order to enter in the PIN code sequence. Compared with the keypad layout, empirical results show that PIN digit entry errors do not differ significantly between interfaces, although the rotary incurs fewer errors overall. Expressing preference for the rotary, users appeared to quickly grasp its operation.