Traum’s research focuses on Dialogue Communication between Human and Artificial Agents. He has engaged in theoretical, implementational and empirical approaches to the problem, studying human-human natural language and multi-modal dialogue, as well as building a number of dialogue systems to communicate with human users. These systems have ranged in complexity from simple command and control and system-directed information-providing systems to full mixed-initiative collaborative planning and interaction, and have included both uni-modal (text or speech) and multimodal (gesture, sketching, pointing) systems. One major thrust of research includes the "grounding" problem -- how do communicators realize how well they are understanding each other, and what steps can and should they take to increase this mutual understanding (including giving positive and negative feedback, in a variety of modalities).