Processing conventional and non-conventional multiword units: evidence of similarity-based generalisation from judgements and brain potentials

Language is constantly evolving through speakers’ natural innovations. However, our understanding of how subtle linguistic innovations are processed is still surprisingly limited. To date, most studies investigating processing of non-conventional language have focused on metaphors. Using both brain event-related potentials (ERPs) and offline judgements, the present study investigated the acceptability, as well as the temporal dynamics, associated with processing novel and conventional multiword units. By manipulating both the degree of similarity and degree of conventionality, the results revealed that the acceptability of novel items hinges on their similarity to known multiword units. ERPs revealed that similarity modulated a late positive component (LPC) 550–750 ms after stimulus presentation; this LPC was significantly correlated with acceptability. Additionally, processing of novel multiword units was not modulated by exposure to related multiword units, indicating that similarity-based processing was not dependent on recent prior exposure.