Intermanual Deictics: Uncovering Users' Gesture Preferences for Opposite-Arm Referential Input, from Fingers to Shoulder

We examine intermanual deictics, a distinctive class of gesture input characterized by an intermanual structure, asymmetric postural-manipulative articulation, and a deictic nature, drawing from both on-skin and bimanual mid-air gestures. To understand user preferences for gestures featuring these characteristics, we conducted a large-sample end-user elicitation study with 75 participants, who proposed intermanual deictics involving the opposite palm, forearm, and upper arm. Our results reveal a strong preference for physical-contact gestures primarily performed with the index finger, with strokes (62.4%) and touch input (28.8%) being most common, complemented by some preference for non-contact gestures (5.2%). We report similar agreement rates across gestures elicited in the three arm regions, averaging 26.3%, with higher agreement between the forearm and upper arm. We also present a consensus set of sixty gestures for effecting generic commands in interactive systems, along with design principles encompassing multiple practical implications for interactions that incorporate intermanual deictics.