Hanna's research predominantly investigates bi/multilingual acquisition over the lifespan and the factors that moderate proficiency. Her research specifically looks at Welsh-English bilinguals' acquisition of complex grammar and vocabulary, and how factors such as input properties, use of language and attitudes predict attainment. Hanna is currently expanding on this research to look at the acquisition trajectories of children who are acquiring Welsh and English as additional languages. Beyond acquisition research, some of her current projects include how Welsh-English bilinguals social use of their languages across domains effects language dominance. With colleagues in Welsh and the Law department, she is looking at the use of simultaneous translation in Welsh courtrooms. 

Hanna is an applied psycholinguist with an expertise in bilingualism. She has been a lecturer in psychology at Aberystwyth University since 2019.