Twist 'n' Knock: A One-handed Gesture for Smart Watches

Interacting with a smart watch requires a fair amount of attention, which can disrupt a user's primary activity. While single-handed gestures have been developed for other platforms, they are cumbersome to perform with a watch. A simple interaction is needed that can be used to quickly and subtly access the watch at the user's convenience. In this paper, we developed Twist "n" Knock--a one-handed gesture that can quickly trigger functionality on a smart watch without causing unintended false positives. This gesture is performed by quickly twisting the wrist that wears the watch and then knocking on a nearby surface such as the thigh when standing or a table when sitting. Our evaluation with 11 participants shows that by chunking the twisting and knocking motion into a combined action, Twist 'n' Knock offers distinct features that produced only 2 false positives over a combined 22 hours of real world collection (11 users for 2 hours each). In structured tests, accuracy was 93%.