Mass and Count nouns activate different brain regions: anERP study on early components

In the present study, event related brain potentials (ERPs) showed that, in an implicit Lexical decision task in which participants had to decide whether a word or a pseudoword was presented, a very early distinction between Mass and Count nouns was found at 160 ms after word onset (N150). Mass nouns elicited greater left-lateralization over frontal locations while Count nouns were more lateralized in the left occipito-parietal sites. In the 430-490 ms interval activity and lateralization shifted to anterior sites and a different distribution was found between Mass nouns, Count nouns and Pseudowords. Mass nouns showed greater left-lateralization both in anterior and posterior regions, whereas Count nouns showed relatively less left-lateralization especially over frontal cortex. Results point to a functional distinction between Mass and Count nouns as indicated by the very early automatic N150 difference between the two categories. Count nouns involved left visual associative regions that are typically relevant for object recognition and categorization. Mass nouns, instead, required the activation of more widely spread out linguistic networks that included also left frontal sites, a result that indicates a more difficult and engaging automatic retrieval and an extended cortical representation of these nouns.