Target Based Speech Act Classification in Political Campaign Text

Proceedings of the Eighth Joint Conference on Lexical and Computational Semantics (*SEM), pages 273–282 Minneapolis, June 6–7, 2019. c⃝2019 Association for Computational Linguistics 273 Target Based Speech Act Classification in Political Campaign Text Shivashankar Subramanian Trevor Cohn Timothy Baldwin School of Computing and Information Systems The University of Melbourne shivashankar@student.unimelb.edu.au {t.cohn,tbaldwin}@unimelb.edu.au Abstract We study pragmatics in political campaign text, through analysis of speech acts and the target of each utterance. We propose a new annotation schema incorporating domain- specific speech acts, such as commissive- action, and present a novel annotated corpus of media releases and speech transcripts from the 2016 Australian election cycle. We show how speech acts and target referents can be mod- eled as sequential classification, and evaluate several techniques, exploiting contextualized word representations, semi-supervised learn- ing, task dependencies and speaker meta-data. 1 Introduction Election campaign text is a core artifact in politi- cal analysis. Campaign communication can influ- ence a party’s reputation, credibility, and compe- tence, which are primary factors in voter decision making (Fernandez-Vazquez, 2014). Also, mod- eling the discourse is key to measuring the role of party in constructive democracy — to engage in constructive discussion with other parties in a democracy (Gibbons et al., 2017). Speech act theory (Austin, 1962; Searle, 1976) can be used to study such pragmatics in political campaign text. Traditional speech act classes have been studied to analyze how people engage with elected members (Hemphill and Roback, 2014), and how elected members engage in discussions (Shapiro et al., 2018), with a particular focus on pledges (Artés, 2011; Naurin, 2011, 2014; Gib- bons et al., 2017). Also, election manifestos have been analyzed for prospective and retrospective messages (Müller, 2018). In this work, we com- bine traditional speech acts with those proposed by political scientists to study political discourse, such as specific pledges, which can also help to verify the pledges’ fulfilment after an election (Thomson et al., 2010). In addition to speech acts, it is important to identify the target of each utterance — that is, the political party referred to in the text — in order to determine the discourse structure. Here, we study the effect of jointly modeling the speech act and target referent of each utterance, in order to exploit the task dependencies. That is, this paper is an ap- plication of discourse analysis to the pragmatics- rich domain of political science, to determine the intent of every utterance made by politicians, and in part, automatically extract pledges at varying levels of specificity from campaign speeches and press releases. We assume that each utterance is associated with a unique speech act (similar to Zhao and Kawahara (2017)) and target party,1 meaning that a sentence with multiple speech acts and/or targets must be segmented into component utterances. Take the following example, from the Labor Party: (1) Labor will contribute $43 million towards the Roe Highway project and we call on the WA Government to contribute funds to get the project underway. The example is made up of two utterances …

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