Multilingual Subjectivity Analysis Using Machine Translation

Proceedings of the 2008 Conference on Empirical Methods in Natural Language Processing, pages 127–135, Honolulu, October 2008. c⃝2008 Association for Computational Linguistics Multilingual Subjectivity Analysis Using Machine Translation Carmen Banea and Rada Mihalcea University of North Texas carmenb@unt.edu, rada@cs.unt.edu Janyce Wiebe University of Pittsburgh wiebe@cs.pitt.edu Samer Hassan University of North Texas samer@unt.edu Abstract Although research in other languages is in- creasing, much of the work in subjectivity analysis has been applied to English data, mainly due to the large body of electronic re- sources and tools that are available for this lan- guage. In this paper, we propose and evalu- ate methods that can be employed to transfer a repository of subjectivity resources across lan- guages. Specifically, we attempt to leverage on the resources available for English and, by employing machine translation, generate re- sources for subjectivity analysis in other lan- guages. Through comparative evaluations on two different languages (Romanian and Span- ish), we show that automatic translation is a viable alternative for the construction of re- sources and tools for subjectivity analysis in a new target language. 1 Introduction We have seen a surge in interest towards the ap- plication of automatic tools and techniques for the extraction of opinions, emotions, and sentiments in text (subjectivity). A large number of text process- ing applications have already employed techniques for automatic subjectivity analysis, including auto- matic expressive text-to-speech synthesis (Alm et al., 2005), text semantic analysis (Wiebe and Mihal- cea, 2006; Esuli and Sebastiani, 2006), tracking sen- timent timelines in on-line forums and news (Lloyd et al., 2005; Balog et al., 2006), mining opinions from product reviews (Hu and Liu, 2004), and ques- tion answering (Yu and Hatzivassiloglou, 2003). A significant fraction of the research work to date in subjectivity analysis has been applied to English, which led to several resources and tools available for this language. In this paper, we explore multiple paths that employ machine translation while lever- aging on the resources and tools available for En- glish, to automatically generate resources for sub- jectivity analysis for a new target language. Through experiments carried out with automatic translation and cross-lingual projections of subjectivity annota- tions, we try to answer the following questions. First, assuming an English corpus manually an- notated for subjectivity, can we use machine trans- lation to generate a subjectivity-annotated corpus in the target language? Second, assuming the availabil- ity of a tool for automatic subjectivity analysis in English, can we generate a corpus annotated for sub- jectivity in the target language by using automatic subjectivity annotations of English text and machine translation? Finally, third, can these automatically generated resources be used to effectively train tools for subjectivity analysis in the target language? Since our methods are particularly useful for lan- guages with only a few electronic tools and re- sources, we chose to conduct our initial experiments on Romanian, a language with limited text process- ing resources developed to date. Furthermore, to validate our results, we carried a second set of ex- periments on Spanish. …

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