A comparison of the verbal vocabulary of Parkinson’s Disease patients and healthy speakers

Abstract

In research on the motor grounding of action language, the study of language users suffering from an impairment of the motor system may provide important insights. One such group are Parkinson’s Disease (PD) patients, who have been shown to exhibit effects of an impaired motor grounding. Evidence for this impairment has been obtained in a number of language-processing experiments. The present study extends this line of research by testing whether this impairment affects the semantic quality of the vocabulary of PD patients. We address this question by analyzing a corpus containing narratives of two fairy tales produced by German-speaking PD patients and a control group of healthy speakers. More specifically, we employ semantic vectors in two separate analyses to test the hypothesis of a reduced action-dominance in the verbal vocabulary of PD patients compared to healthy controls. The findings show a mixed pattern, with the results for one set of narratives aligning more robustly with the main hypothesis than the results for the other. We discuss the results against the background of previous findings and point out their implications for research on the motor grounding of action language and its representation in the mental lexicon.