Whack gestures

We introduce Whack Gestures, an inexact and inattentive interaction technique. This approach seeks to provide a simple means to interact with devices with minimal attention from the user -- in particular, without the use of fine motor skills or detailed visual attention (requirements found in nearly all conventional interaction techniques). For mobile devices, this could enable interaction without "getting it out," grasping, or even glancing at the device. This class of techniques is suitable for a small number of simple but common interactions that could be carried out in an extremely lightweight fashion without disrupting other activities. With Whack Gestures, users can interact by striking a device with the open palm or heel of the hand. We briefly discuss the development and use of a preliminary version of this technique and show that implementations with high accuracy and a low false positive rate are feasible.