Modelling spoken dialogues with state transition diagrams: experiences with the CSLU toolkit

The development of a spoken dialogue system is a complex process involving the integration of several component technologies. Various toolkits and authoring environments have been produced that provide assistance with this process. This paper reports on several projects involving CSLU’s RAD (Rapid Application Developer) and critically evaluates the applicability of state transition diagrams for modelling different types of spoken dialogue. State transition methods have been recommended for dialogues that involve well-structured tasks that can be mapped directly on to a dialogue structure. However, other significant factors to be considered include the structure of the information to be transacted and the need for verification of the user's input as determined by the system's level of recognition accuracy. Examples of different types of dialogue are presented together with recommendations concerning the advantages and disadvantages of state transition based dialogue control.