  Moral framing and sentiment can affect a variety of online and offline
behaviors, including donation, pro-environmental action, political engagement,
and even participation in violent protests. Various computational methods in
Natural Language Processing (NLP) have been used to detect moral sentiment from
textual data, but in order to achieve better performances in such subjective
tasks, large sets of hand-annotated training data are needed. Previous corpora
annotated for moral sentiment have proven valuable, and have generated new
insights both within NLP and across the social sciences, but have been limited
to Twitter. To facilitate improving our understanding of the role of moral
rhetoric, we present the Moral Foundations Reddit Corpus, a collection of
16,123 Reddit comments that have been curated from 12 distinct subreddits,
hand-annotated by at least three trained annotators for 8 categories of moral
sentiment (i.e., Care, Proportionality, Equality, Purity, Authority, Loyalty,
Thin Morality, Implicit/Explicit Morality) based on the updated Moral
Foundations Theory (MFT) framework. We use a range of methodologies to provide
baseline moral-sentiment classification results for this new corpus, e.g.,
cross-domain classification and knowledge transfer.
