As discussed in Section 2.3, under the adaptationas-priming paradigm, we would expect sentences that share the same specific structure to be more similar to each other than lexically matched sentences that do not share the structure.
9 if X 1 and X 2 are non-lexically-overlapping sets of sentences with shared structure S X , and Y 2 is a set of sentences with structure S Y , but is lexically matched with X 2 , then we would expect AE(X 2 | X 1 ) > AE(Y 2 | X 1 ).