An understanding of what makes a user interface habitable and natural is needed. Man-machine interfaces must be helpful and cooperative to be usable, especially when difficult situations occur in the interaction. User acceptance of these interfaces depends on their error robustness and their ability to provide assistance. This is especially important for error-prone input such as speech. In this paper we describe several generic mechanisms that have been developed to provide user guidance and improve naturalness in the PARTNER man-machine dialogue system. It is shown how these mechanisms can be used to ease the interaction with naive users and facilitate error recovery. Finally we present some results obtained in the case of an object manipulation tool developed with PARTNER.
Keywords: Help, Error recovery, Multimodal dialogue