The Advantage of the Ungrammatical

The Advantage of the Ungrammatical Laura Staum Casasanto (lstaum@stanford.edu) Department of Linguistics, Margaret Jacks Hall Stanford, CA 94305 USA Ivan A. Sag (sag@stanford.edu) Department of Linguistics, Margaret Jacks Hall Stanford, CA 94305 USA the subject noun phrase (NP) of its complement clause, e.g. he in (1): Abstract Sentences with multiple complementizers like I told him that for sure that I would come often occur in speech and even in writing, although they would not normally be generated by a competence grammar. Here we conducted an acceptability study and a self-paced reading experiment to test whether these 'Multiple That' constructions are acceptable, and whether they are motivated by processing difficulty. Results showed that the presence of an extra complementizer always reduced the acceptability of sentences relative to single- complementizer versions, suggesting that this construction is not licensed by the grammar. However, the penalty incurred by the extra complementizer was smaller when more material intervened between the verb and the embedded clause, making integration costs high. In addition, reading times were faster on the embedded subject in Multiple That sentences compared to sentences with only one that in these more difficult sentences, suggesting that the extra that actually helps readers understand hard-to-process complement clauses. Multiple That need not be generated by the grammar under a theory of performance that allows processing pressures to add structures to the set of possible sentences. (1) I agreed that he was too late. Formal grammars of English generate complementizers exclusively at the beginning of complement clauses. While there is variation in whether or not an overt complementizer appears in this position, grammatical constraints require that when there is an overt complementizer, it must appear immediately before any material that is part of the embedded clause. Although this is the only restriction that specifies the location of the complementizer, in this type of sentence, material that intervenes between the verb and the complement is uncommon. As a consequence, the complementizer is usually contiguous with both the verb that selects it and the subject of the clause it introduces, and by virtue of this contiguity, it can serve as a signal of two things. First, the complementizer clarifies the argument structure of the verb by signaling that a clause is upcoming and that this clause will serve as the complement of the verb; it usually appears in exactly the position where an NP would appear if the verb had an NP complement: Keywords: Sentence processing; syntax. Introduction The competence/performance distinction (as described in Chomsky and Miller, 1963) has fallen under attack in the face of empirical results demonstrating the complex relationships among acceptability, grammaticality, and processing. Proposals for the total elimination of the competence component (O’Grady, 2007) suggest that characteristics of language previously attributed to grammar can be accounted for instead by a parsimonious set of constraints on the parser. Even researchers who do not favor doing away with grammar have proposed processing explanations for phenomena previously understood in grammatical terms (Arregui, Clifton, Frazier and Moulton, 2006; Hofmeister et al. 2007). These empirical results suggest reevaluating the interaction between competence and performance in the explanation of linguistic data. In the current study we investigated a new phenomenon, which we call Multiple That, in which speakers produce sentences that contain more than one complementizer to introduce a single complement clause. In natural speech, the complementizer that typically appears between a complement-taking verb like agreed and (2) I told him {a story, that I was coming}. Many of the verbs that can take a sentential complement as an argument can also take an NP complement, and so the argument structure of the verb is ambiguous until there is some clear sign that the material following the verb is part of either a clause or an NP. An overt complementizer in speech constitutes such a clear sign, and allows the listener to assign an argument structure to the verb immediately upon interpreting it. Second, that signals that the subject of the clause is immediately upcoming, making this subject highly predictable and easier to process when it appears. An efficient parser could learn, by tracking statistics, to interpret the complementizer as a signal of these two things, thereby making it easier to assign an argument structure to the matrix verb and to integrate the subject of the complement clause into the parse when it appears. Importantly, it is only possible for a single item to perform this dual function when the verbal complement position