A model of back-channel acknowledgements in spoken dialogue Nicola Cathcart author Jean Carletta author Ewan Klein author 2003-04 text 10th Conference of the European Chapter of the Association for Computational Linguistics Ann Copestake editor Jan Hajič editor Association for Computational Linguistics Budapest, Hungary conference publication cathcart-etal-2003-model https://aclanthology.org/E03-1069/ 2003-04