Experimental evidence for the truth conditional contribution and shifting information status of appositives

Appositive constructions (My friend Sophie, (who is) a classical violinist, performed a piece by Mozart) have stood at the center of debates concerning the range of possible meanings, and more specifically the status of not-at-issue entailments. However, it remains an open question what precisely their semantic and pragmatic contribution is to the sentence in which they appear. Here, we address this question head-on experimentally. We first investigate the information status of appositives and find that while nominal appositives (e.g. a classical violinist) and sentence-medial appositive relative clauses (e.g. who is a classical violinist) are largely not at issue, sentence-final appositive relative clauses can become at issue, as witnessed in their becoming the target of a direct rejection and being associated with subsequent questions. We then investigate the truth conditional contribution of appositives to sentences in which they appear, and find that whenever an appositive is false, participants judge the entire sentence False. Reaction times complement truth value ratings to demonstrate that this decision is largely automatic. We discuss possible reasons for the difference among appositive types and sentential positions, and propose that the pattern of results we observe and the strong similarity with conjunction can best be accounted for in a unidimensional semantics which treats appositives as dynamic conjuncts but which also relates linguistic form to the timing of making assertions in discourse.