Her primary research interests include historical linguistics, semantics and meaning changes, the semantics of grammatical constructions, cognitive linguistics, metaphor and iconicity, subjectivity and viewpoint, the relationship between language and gesture, and the Celtic language family.
Her 1990 book, From Etymology to Pragmatics (Cambridge University Press), explores generalizations about synchronic and diachronic patterns of meaning in the areas of model verbs and conjunctions. Her 2005 book coauthored with Barbara Dancygier, Mental Spaces in Grammar: Conditional Conditional Constructions, examined the ways in which conditional constructions elaborate human cognitive structures of reasoning.
She has served as Director of both the Program in Cognitive Science and the Program in Celtic Studies. She has published articles on topics including modality, polysemy, metaphor, mental spaces theory, conditional constructions, co-speech gesture, and linguistic approaches to poetic texts, and has a forthcoming volume on Viewpoint (co-edited with Barbara Dancygier) which will appear in Spring 2012 from Cambridge University Press.