Subject encodings and retrieval interference

•The processing at an English verb is more difficult when its subject is complex, and contains other subjects.•This processing difficulty is more acute when embedded subjects are similar to the target subject in case and position.•Complex embedded subjects, not objects, lead to difficulty, supporting structural retrieval cues.•Accusative subjects embedded by verbs like believe may facilitate processing, when complex. Interference has been identified as a cause of processing difficulty in linguistic dependencies, such as the subject-verb relation (Van Dyke and Lewis, 2003). However, while mounting evidence implicates retrieval interference in sentence processing, the nature of the retrieval cues involved - and thus the source of difficulty - remains largely unexplored. Three experiments used self-paced reading and eyetracking to examine the ways in which the retrieval cues provided at a verb characterize subjects. Syntactic theory has identified a number of properties correlated with subjecthood, both phrase-structural and thematic. Findings replicate and extend previous findings of interference at a verb from additional subjects, but indicate that retrieval outcomes are relativized to the syntactic domain in which the retrieval occurs. One, the cues distinguish between thematic subjects in verbal and nominal domains. Two, within the verbal domain, retrieval is sensitive to abstract syntactic properties associated with subjects and their clauses. We argue that the processing at a verb requires cue-driven retrieval, and that the retrieval cues utilize abstract grammatical properties which may reflect parser expectations.