Developing a robot system that can interact directly with a human instructor in a natural way requires not only highly-skilled sensorimotor coordination and action planning on the part of the robot, but also the ability to understand and communicate with a human being in many modalities. A typical application of such a system is interactive assembly for construction tasks. A human communicator sharing a common view of the work area with the robot system instructs the latter by speaking to it in the same way that he would communicate with a human partner.