66 International Journal of Technology and Human Interaction, 9(2), 66-88, April-June 2013 Copyright © 2013, IGI Global. Copying or distributing in print or electronic forms without written permission of IGI Global is prohibited. Copyright © 2013, IGI Global. Copying or distributing in print or electronic forms without written permission of IGI Global is prohibited. Avatar and Dialog Turn-Yielding Phenomena Ladislav Kunc, Department of Computer Graphics and Interaction, Czech Technical University in Prague, Prague, Czech Republic Zdeněk Míkovec, Department of Computer Graphics and Interaction, Czech Technical University in Prague, Prague, Czech Republic Pavel Slavík, Department of Computer Graphics and Interaction, Czech Technical University in Prague, Prague, Czech Republic ABSTRACT Turn-taking and turn-yielding phenomena in dialogs receive increasing attention nowadays. A growing number of spoken dialog systems inspire application designers to humanize people’s interaction experience with computers. The knowledge of psychology in discourse structure could be helpful in this effort. In this paper the authors explore effectiveness of selected visual and vocal turn-yielding cues in dialog systems using synthesized speech and an avatar. The aim of this work is to detect the role of visual and vocal cues on dialog turn-change judgment using a conversational agent. The authors compare and study the cues in two experi- ments. Findings of those experiments suggest that the selected visual turn-yielding cues are more effective than the vocal cues in increasing correct judgment of dialog turn-change. Vocal cues in the experiment show quite poor results and the conclusion discusses possible explanations of that. Keywords: Dialog Systems, Embodied Conversational Agent, Human Computer Interaction, Turn-Taking, Turn-Yielding INTRODUCTION Implementation of systems able to interact with humans in a natural conversational way to pro- vide services, that would otherwise require com- munication by means of human phone operators or menu graphical-based systems, represents the ultimate goal of human-computer interaction designers. A voice based user interface is one of the possible human-computer interaction methods. Last few years have brought many advances in automatic speech recognition systems, text-to-speech systems, and in dialog management systems. These systems are getting more and more sophisticated and as such they have grown relatively complex. A good example of this trend could be automatic telephone sys- tems which help users solve simple problems in daily life and, in difficult cases, reroute the customer to appropriate human operator. AT&T ‘How may I help you?’ system is credited to be the first among such advanced systems (Gorin, Riccardi, & Wright, 1997). However, computer DOI: 10.4018/jthi.2013040105