Investigating inflection as a complex system

From a cross-linguistic perspective, different inflection systems appear to apportion word processing costs differently, depending on when and where, in the full form, morpho-lexical and morpho-syntactic information is encoded. The resulting balance is the outcome of an interaction between form frequency and morphological productivity, responding to basic communicative requirements. Big families of stem-sharing inflected forms constitute the productive core of an inflection system. This core is easy to learn, as it requires memorization of one stem only, with all inflected forms being redundantly built upon it. Unsurprisingly, generalizable paradigms are less sensitive to token frequency effects, and tend to be located in the long, low-frequency tail of the Zipfian distribution of word forms. In contrast, the head of the Zipfian distribution mostly contains small families of alternating and possibly suppletive stems, which, however shorter, morpho-phonologically simpler and easier to process, require high token frequency to be learned and resist pressure towards regularization.