Modelling the Usage of Discourse Connectives as Rational Speech Acts

Frances Yung1, Kevin Duh2, Taku Komura3, Yuji Matsumoto1
1Nara Institute of Science and Technology, 2Johns Hopkins University, 3University of Edinburgh


Discourse relations can either be implicit or explicitly expressed by markers, such as ’therefore’ and ’but’. How a speaker makes this choice is a question that is not well understood. We propose a psycholinguistic model that predicts whether a speaker will produce an explicit marker given the discourse relation s/he wishes to express. Based on the framework of the Rational Speech Acts model, we quantify the utility of producing a marker based on the information-theoretic measure of surprisal, the cost of production, and a bias to maintain uniform information density throughout the utterance. Experiments based on the Penn Discourse Treebank show that our approach outperforms state-of- the-art approaches, while giving an explanatory account of the speaker’s choice.