Beyond grammatical category: The role of distributional properties of Italian language in processing nouns and verbs

This contribution offers an overview on the main studies carried out on the difference between verb and noun processing in adults and children. This topic will be discussed, in particular, according to the perspective we proposed in collaboration with Cristina Burani, focused on the role of language distributional properties in word processing. This issue has been developed in the last 20 years by assessing differences between words with small inflectional family size, i.e. nouns and adjectives (which in Italian can be inflected in 2-4 word forms), and words with large inflectional family size, i.e. verbs (which can be inflected in up to 50 different word forms). This comparison was made through several tasks (lexical decision, progressive de-masking, reading aloud, a grammatical-class switching task, picture naming) and in different populations, i.e. skilled adult readers, adults with aphasia, adults with Parkinson’s Disease, typically developing children and children with dyslexia. In all these studies we found that verb bases are more likely to be processed as base + suffix combination, and are usually associated with slower RTs and lower accuracy than noun bases. Neuroimaging techniques, used in some of these studies, showed that different brain areas are activated in noun and verb processing, as verb recognition seems to involve selection and inhibition mechanisms that are not detected in the case of noun processing. As for nouns, both whole-word and base-word representations seem to be available and their activation is mainly affected by word- and base-frequency, respectively. Overall, data from these studies suggests that the difference between nouns and verbs can depend not only on grammatical, syntactic, and semantic features, but also on the different morphological family size, which might determine difficulty in selection and inhibition processes.