Two sides of gender: ERP evidence for the presence of two routes during gender agreement processing

The present ERP study aimed at providing evidence for the existence of two routes in the brain for the processing of morphosyntactic features during language comprehension; a lexical route which retrieves grammatical properties stored in the lexicon without reliance on formal cues, and a form-based route that takes advantage of sub-lexical units strongly related to a specific grammatical class. In the experiment, we investigated grammatical gender agreement processing in Spanish article-noun word pairs using a grammaticality judgment task. Article-noun pairs either agreed or did not agree in gender. Noun transparency was manipulated such that the ending could be strongly associated with a specific gender class (i.e., transparent nouns) or not (i.e., opaque nouns). A visual half-field method was employed and ERPs were recorded in response to the target nouns in order to disentangle the initial hemisphere-specific computations of gender processing. ERP results showed that, while both hemispheres compute agreement dependencies, the left hemisphere is sensitive to the presence of formal gender cues at an early stage (i.e., 350-500 ms) indicating the presence of a form-based route. The right hemisphere showed an ERP effect of transparency, but later than the left hemisphere (i.e., 500-750 ms). These findings confirm the presence of two routes to gender, which can be differently used depending on the availability of transparent endings. In addition, the results showed hemispheric differences in the time course of the form-based route.