Rules or schemas? Evidence from Polish

At least three factors—regularity, type frequency, and phonological heterogeneity—have been claimed to be implicated in determining the likelihood that a particular inflection will be applied to new stems. The role of these factors in determining Polish speakers’ productivity with genitive and dative inflections was investigated using nonce word production tasks and spontaneous child language data. Both children and adults freely generalised genitive masculine inflections, which are irregular but apply to large classes of phonologically heterogeneous nouns. However, speakers were only weakly productive with genitive neuter and dative neuter inflections, in spite of the fact that they are almost completely regular. This is attributed to the fact that the neuter class is relatively small, and that most nouns are clustered in a few densely populated phonological neighbourhoods. Thus, type frequency and phonological heterogeneity appear to be much better predictors of productivity than regularity. These findings are discussed in the context of single and dual mechanism approaches to morphological productivity.