Inspired by the dynamic clamp of cellular neuroscience, this paper introduces VPI—Virtual Partner Interaction—a coupleddynamical system for studying real time interaction between a human and a machine. In this proof of concept study, humansubjects coordinate hand movements with a virtual partner, an avatar of a hand whose movements are driven by acomputerized version of the Haken-Kelso-Bunz (HKB) equations that have been shown to govern basic forms of humancoordination. As a surrogate system for human social coordination, VPI allows one to examine regions of the parameterspace not typically explored during live interactions. A number of novel behaviors never previously observed are uncoveredand accounted for. Having its basis in an empirically derived theory of human coordination, VPI offers a principled approachto human-machine interaction and opens up new ways to understand how humans interact with human-like machinesincluding identification of underlying neural mechanisms.