  Insights into social phenomenon can be gleaned from trends and patterns in
corpora of documents associated with that phenomenon. Recent years have
witnessed the use of computational techniques, mostly based on keywords, to
analyze large corpora for these purposes. In this paper, we extend these
techniques to incorporate semantic features. We introduce Doris, an interactive
exploration tool that combines semantic features with information retrieval
techniques to enable exploration of document corpora corresponding to the
social phenomenon. We discuss the semantic techniques and describe an
implementation on a corpus of United States (US) presidential speeches. We
illustrate, with examples, how the ability to combine syntactic and semantic
features in a visualization helps researchers more easily gain insights into
the underlying phenomenon.
