Variation in the use of syntactic alternations has long been an explanatory target of language production theories. In this work, we test the predictions of several semantic, pragmatic and psycholinguistic theories of language use for the English dative alternation. We first experimentally test the role of incremental constituent informativity in the dative alternation, and find that contrary to information structural and RSA models of production, informativity has little effect on production preferences. We then more rigorously focus on accessibility effects, demonstrating that a lossy-context automatic policy can recover a key pattern of accessibility. Ultimately, we conclude that audience design pressures likely do not influence incremental production, but simply may affect planning at a broader scope.

Languages often express grammatical information through inflectional morphology, in which grammatical features are grouped into strings of morphemes. In this work, we propose that cross-linguistic generalizations about morphological fusion, in which multiple features are expressed through one morpheme, can be explained in part by optimization of processing efficiency, as formalized using the memory--surprisal tradeoff of Hahn et al. (2021). We show in a toy setting that fusion of highly informative neighboring morphemes can lead to greater processing efficiency under our processing model. Next, based on paradigm and frequency data from four languages, we consider both total fusion and gradable fusion using empirical measures developed by Rathi et al. (2021), and find that the degree of fusion is predicted by closeness of optimal morpheme ordering as determined by optimization of processing efficiency. Finally, we show that optimization of processing efficiency can successfully predict typological patterns involving suppletion.