The role of the language production system in shaping grammars

We argue for an extension of the proposal that grammars are in part shaped by processing systems. Hawkins (2014) and others who have advanced this idea focus primarily on parsing. Our extension focuses on production, and we use that to explore explanations for certain subject/object asymmetries in extraction structures. The phenomenon we examine, which we term the mirror asymmetry , runs in opposite directions for within-clause and across-clause (long-distance) extraction, showing a preference for subject extraction in the former and for object extraction in the latter. We review several types of evidence suggesting that the mirror asymmetry and related phenomena are best explained by an account of the formation of grammars that assigns an important role to properties of sentence planning in production.