If priming is graded rather than all-or-none, can reactivating abstract structures be the underlying mechanism?

In our commentary on Branigan & Pickering (B&P), we start by arguing that the authors implicitly adopt several assumptions, the consequence of which is to make further claims necessary and/or sufficient. Crucially, the authors assume the existence of discrete units at various levels of linguistic granularity that then must be operated upon by combinatorial mechanisms and rules (i.e., decomposition/recomposition). They further argue that structural priming provides a powerful tool to study abstract, structural representations. We provide evidence that priming effects in production are characterized better as graded than as all-or-none and that priming need not arise from a mechanism that (re)activates a shared but abstract internal structure.