<?xml version="1.0" standalone="yes"?>
<Paper uid="W06-2915">
  <Title>Which Side are You on? Identifying Perspectives at the Document and Sentence Levels</Title>
  <Section position="4" start_page="109" end_page="109" type="relat">
    <SectionTitle>
2 Related Work
</SectionTitle>
    <Paragraph position="0"> Identifying the perspective from which a document is written is a subtask in the growing area of automatic opinion recognition and extraction. Subjective language is used to express opinions, emotions, and sentiments. So far, research in automatic opinion recognition has primarily addressed learning subjective language (Wiebe et al., 2004; Riloff et al., 2003), identifying opinionated documents (Yu and Hatzivassiloglou, 2003) and sentences (Yu and Hatzivassiloglou, 2003; Riloff et al., 2003), and discriminating between positive and negative language (Pang et al., 2002; Morinaga et al., 2002; Yu and Hatzivassiloglou, 2003; Turney and Littman, 2003; Dave et al., 2003; Nasukawa and Yi, 2003; Popescu and Etzioni, 2005; Wilson et al., 2005). While by its very nature we expect much of the language that is used when presenting a perspective or point-of-view to be subjective, labeling a document or a sentence as subjective is not enough to identify the perspective from which it is written. Moreover, the ideology and beliefs authors possess are often expressed in ways other than positive or negative language toward specific targets.</Paragraph>
    <Paragraph position="1"> Research on the automatic classification of movie or product reviews as positive or negative (e.g., (Pang et al., 2002; Morinaga et al., 2002; Turney and Littman, 2003; Nasukawa and Yi, 2003; Mullen and Collier, 2004; Beineke et al., 2004; Hu and Liu, 2004)) is perhaps the most similar to our work. As with review classification, we treat perspective identification as a document-level classification task, discriminating, in a sense, between different types of opinions. However, there is a key difference. A positive or negative opinion toward a particular movie or product is fundamentally different from an overall perspective. One's opinion will change from movie to movie, whereas one's perspective can be seen as more static, often underpinned by one's ideology or beliefs about the world.</Paragraph>
    <Paragraph position="2"> There has been research in discourse analysis that examines how different perspectives are expressed in political discourse (van Dijk, 1988; Pan et al., 1999; Geis, 1987). Although their research may have some similar goals, they do not take a computational approach to analyzing large collections of documents. To the best of our knowledge, our approach to automatically identifying perspectives in discourse is unique.</Paragraph>
  </Section>
class="xml-element"></Paper>