Intersecting formatives and inflectional predictability: How do speakers and learners predict the correct form of Murrinhpatha verbs?
This article investigates the phenomenon of inflection by intersecting formatives, that is to say, where an exponence is encoded by a combination of independently distributed phonological increments. Formative independence is defined in terms of conditional entropy. The verb inflection system of Murrinhpatha, an Aboriginal language of northern Australia, is analysed as a particularly complex example of intersecting formatives, and in general we can say that inflectional exponence in this language is highly irregular or unpredictable. Recent information-theoretic approaches to morphology provide us with methods for formalising and measuring the unpredictability of Murrinhpatha verb inflection. We add a distinct formalism that models the probability of correct inflectional prediction given incomplete knowledge of the inflectional paradigms in the language. We argue that this is a particularly relevant model for Murrinhpatha speaker/learners, because the language has a small, closed class of finite verb lexemes, most of which have their own idiosyncratic inflectional paradigm. There are not productively applied inflectional classes. In this model of inflectional predictability, intersecting formatives are in some cases the only chance a learner/speaker has of predicting the correct form.