Belly gestures: body centric gestures on the abdomen

Recent HCI research has shown that the body offers an interactive surface particularly suitable to eyes-free interaction. While researchers have mainly focused on the arms and the hands, we argue that the surface of the belly is especially appropriate. The belly offers a fairly large surface that can be easily reached with the two hands in any circumstance, including walking or running. We report on a study that explored how users perform one-handed gestures on their abdomen. Users use different mental spatial orientations depending on the complexity of the gesture they have to draw (drawing a digit vs. a simple directional stroke). When provided with no visual orientation cues they often draw gestures following symmetries relative to a horizontal or vertical axis. The more complex the gesture, the less stability in orientation. Focusing on directional strokes, we found that users are able to draw almost linear gestures, despite the fact that the abdomen is not perfectly planar, and perform particularly well in cardinal directions. The paper ends up with some guidelines that may inform the design of novel interaction techniques.