Bock K
Cognition. 1989 Mar;31(2):163-86. doi: 10.1016/0010-0277(89)90022-x.
The closed-class hypothesis asserts that function words play a privileged role in syntactic processes. In language production, the claim is that such words are intrinsic to, identified with, or immanent in phrasal skeletons. Two experiments tested this hypothesis with a syntactic priming procedure. In both, subjects tended to produce utterances in the same syntactic forms as priming sentences, with the structures of the self-generated sentences varying as a function of differences in the structures of the primes. Changes in the closed-class elements of the priming sentences had no effect on this tendency over and above the impact of the structural changes. These results suggest that free-standing closed-class morphemes are not inherent components of the structural frames of English sentences.