The lexical-grammatical divide has been a widely addressed topic in aphasia. Speech parts are generally classified as either belonging to a lexical or a grammatical category based on the frequency of acquisition of new members in their paradigms (open vs. closed classes), thus neglecting heterogeneity within categories. Such an approach has led to contradictory findings. First, prepositions form closed classes, but are classically taken as lexical items. Pronouns, also belonging to a closed class, are analyzed as grammatical elements. Second, both within the group of prepositions and pronouns, forms with different syntactic and semantic properties co-exist.

Following the theoretical notions granted by a usage-based theory of grammar, the ProGram theory, and taking focalizability as the classification criteria, we hypothesize that individuals with non-fluent aphasias will experience more severe problems with grammatical prepositions and pronouns, given that these elements are secondary and dependent, whereas informants in the fluent group will experience more severe trouble with lexical forms, potentially primary and independent. We focused on the performance of nine Spanish-speaking individuals with aphasia from the Rosell (2005) corpus. Samples of 300 words were transcribed and analyzed. As predicted, grammatical prepositions were found to be more severely compromised in the speech output of individuals with deficits of motor predominance, whereas lexical prepositions are more severely affected in individuals with deficits of sensory predominance. Although less conclusively, the same tendency holds in the case of pronouns. Our results, consistent with previous findings, confirm the heterogeneity of prepositions and pronouns, which should no longer be analyzed en bloc.