Multimodal Dialogue Systems: A case study for interactive TV Aseel Ibrahim 1,2 and Pontus Johansson 2 1 Nokia Home Communications, Universitetsvägen 14, S-583 30 Linköping, Sweden 2 Department of Information and Computer Science Linköping University S-581 83 Linköping, Sweden {asebe, ponjo}@ida.liu.se Abstract. Many studies have already shown the advantages of building multi- modal systems. In this case study we have shown the advantages of combining natural language and a graphical interface in the interactive TV domain. In this paper we describe a multimodal dialogue TV program guide system that is a re- search prototype built for the case study by adding speech interaction to an al- ready existing TV program guide. Study results indicate positive attitudes to- wards providing two input modes ? spoken natural language input and direct manipulation by means of remote control. 1 Introduction Many studies have been conducted in order to investigate the advantages of spoken language systems. Studies have reported 20-40% efficiency increase using speech systems compared with other interface technologies, such as keyboard input [1,2]. Rosenfeld et al. [3] divides the advantages of speech into three categories. First, speech is an ambient medium rather than an attentional one, which refers to the possi- bility to interact with the system while doing something else. Second, speech requires modest physical resources. Third, speech is descriptive rather than referential and is powerful to describe objects so it can successfully be combined with other modalities. Combining speech with other modalities is a strategy that has been used when devel- oping multimodal systems where the strength of one modality is used to overcome the weakness of another [4]. Multimodal and dialogue systems have been developed in various domains where speech has been combined with other modalities, for example gestures. Building mul- timodal dialogue systems for the television (TV) domain, which differs from the com- puter domain, has not been explored. The new concept of digital and interactive TV provides a huge range of TV channels, programs, games, and other services. Thus, the problem with a TV program guide with graphical interface manipulated by means of remote control is that the search for a desired program requires many steps. More efficient program guide systems can be provided by combining the flexibility of