Brain mechanisms for processing systematic sound-to-meaning mappings for concrete and abstract concepts

To date, neurobiological accounts of lexical-semantic processing have largely assumed, either explicitly or implicitly, that there is no relationship between the sound of a word and its meaning, despite empirical evidence to the contrary. Recently, multiple representation theories have begun to incorporate non-arbitrary relationships in which a word's form resembles its meaning (iconicity). However, non-arbitrary form-meaning relationships occur more extensively within languages as statistical regularities between sublexical phonological/phonetic features and aspects of word meaning (systematicity or typicality). The present study investigated whether brain activity during lexical processing reflects statistical regularities between sublexical features and concrete and abstract concepts (i.e., concreteness form typicality). Twenty-one healthy participants completed an event-related functional magnetic resonance imaging (fMRI) study while they performed auditory lexical decisions on concrete and abstract words that were highly form-typical. We observed significant activity in a predominantly left-hemisphere network of perisylvian regions previously linked to concrete and abstract word processing. Crucially, the majority of these regions also responded to nonwords constructed with sublexical phonological/phonetic features associated with concreteness, including hub regions proposed to represent amodal conceptual processing. These findings demonstrate that statistical knowledge about non-arbitrary form-meaning mappings constitutes a core component of how concreteness is represented and accessed in the brain. We argue that these results support an account in which concrete and abstract concepts are grounded in the phonetic-acoustic features of language through statistical learning.