The role of kinesthetic reference frames in two-handed input performance

We present experimental work which explores how the match (or mismatch) between the input space of the hands and the output space of a graphical display influences two-handed input performance. During interaction with computers, a direct correspondence between the input and output spaces is often lacking. Not only are the hands disjoint from the display space, but the reference frames of the hands may in fact be disjoint from one another if two separate input devices (e.g. two mice) are used for two-handed input. In general, we refer to the workspace and origin within which the hands operate as kinesthetic reference frames. Our goal is to better understand how an interface designer's choice of kinesthetic reference frames influences a user's ability to coordinate two-handed movements, and to explore how the answer to this question may depend on the availability of visual feedback. Understanding this issue has implications for the design of two-handed interaction techniques and input devices, as well as for the reference principle of Guiard's Kinematic Chain model of human bimanual action. Our results suggest that the Guiard reference principle is robust with respect to variances in the kinesthetic reference frames as long as appropriate visual feedback is present.