VP-adjunction

Definition
VP-adjunction is an adjunction of a constituent to VP. In the Barriers-framework (Cf. Chomsky 1986b), VP-adjunction is a crucial step in the (A'-)movement of direct objects.

Example
If the direct object of a simple sentence would be wh-moved to spec of CP in one step, the result would be (i).

(i)  [CP who [C did] [IP John [VP see t ]]]

This structure is ruled out, because there are two barriers between who and its trace: VP is a non L-marked maximal projection (and therefore a Blocking Category and an inherent barrier), and IP, being the first maximal projection to dominate VP, is a barrier by inheritance. In order to explain the well-formedness of who did John see?, it is assumed by Chomsky that the object first adjoins to VP and only then moves to spec of CP, resulting in (ii).

(ii) [CP who [C did] [IP John [VP t1 [VP see t2 ]]]]

Because barrierhood is defined in terms of exclusion, this step voids the barrierhood of VP and thus that of IP, which is inherited from VP. The possibility of adjunction to VP is required independently to account for certain cases of QR.

Links

 * Utrecht Lexicon of Linguistics