Proceedings of the Annual Meeting of the Cognitive Science Society

A foundational goal of linguistics is to investigate whethershared features of the human cognitive system can explainhow linguistic patterns are distributed across languages. Inthis study we report a series of artificial language learning ex-periments to test a hypothesised link between cognition and apersistent regularity of morpheme order: number morphemes(e.g., plural markers) tend to be ordered closer to noun stemsthan case morphemes (e.g., accusative markers) (Greenberg,1963). We argue that this typological tendency may be drivenby a bias favouring orders that reflect scopal relationships inmorphosyntactic composition (Bybee, 1985; Rice, 2000; Cul-bertson & Adger, 2014). We taught participants an artificiallanguage with noun stems, and case and number morphemes.Crucially, the input language indicated only that each mor-pheme preceded or followed the noun stem. Examples inwhich two (overt) morphemes co-occurred were held out—i.e.,no instances of plural accusatives. At test, participants wereasked to produce utterances, including the held-out examples.As predicted, learners consistently produced number closer tothe noun stem than case. We replicate this effect with freeand bound morphemes, pre- or post-nominal placement, andwith English and Japanese speakers. However, we also findthat this tendency can be reversed when the form of the casemarker is conditioned on the noun, suggesting an influence ofdependency length. Our results provide evidence that univer-sal features of cognition may play a causal role in shaping therelative order of morphemes.