Productive knowledge and item-specific knowledge trade off as a function of frequency in multiword expression processing

We report an experiment eliciting ordering preferences for BINOMIAL EXPRESSIONS (e.g. bread and butter vs. butter and bread) in order to investigate the respective influences of productive and item-specific knowledge in language processing. Binomial ordering preferences reflect both (i) productive constraints involving phonological, semantic, and lexical properties, and (ii) item-specific relative frequencies. Bayesian and exemplar-based computational models of acquisition and use predict influences of both productive and item-specific knowledge on ordering preferences, with item-specific knowledge playing a smaller role the lower the expression's overall frequency. Our results confirm this prediction, but also reveal a role of item-specific knowledge even for binomials with overall frequency less than one in ten million. These findings bring a quantitative perspective to the debate over the roles of productive and item-specific knowledge in language.