Cognitive changes in Parkinson disease (PD) affect language processing, including sentence comprehension impairments, difficulties with processing verbs, and discourse impairments. In many theories of language comprehension, efficient language processing depends on successful implicit prediction of upcoming concepts and grammatical structures. Such prediction processes, in part, may be regulated by the neural dopaminergic system, which is markedly impaired in PD. In non-language tasks, persons with PD (PwPD) are impaired in prediction, sequencing, and probabilistic learning. However, the contributions of these dopaminergic-mediated prediction and probabilistic learning processes to language processing impairments in PD remain unexplored. We tested whether PwPD are impaired in implicit prediction during auditory language processing. The visual-world paradigm was used to investigate implicit predictive eye movements based on verb meaning. Participants listened to semantically predictive and non-predictive sentences while viewing picture stimuli. Both PwPD and controls showed prediction of upcoming nouns from verbs when hearing sentences like “She will drive the car.” Furthermore, PwPD performed equivalently to controls. These results are surprising given the literature, suggesting either that PwPD have normal linguistic prediction, or that more challenging conditions for prediction are required to reveal PD impairments
