Filling the gap in gap-filling: Long distance dependency formation in production

In a sentence like Who does the artist think chased the chef?, the who at the beginning depends on the last bit of the sentence, chased the chef. This is an instance of a long-distance dependency. What is the nature of the cognitive process that allows speakers to produce sentences that include distant elements that form dependencies? In four experiments (total N = 176), speakers described drawings that elicited long-distance dependencies. Critically, speakers were sometimes primed to produce a that in sentences where that was ungrammatical due to a grammatical constraint known as the that-trace constraint (e.g.,*Who does the articist think that chased the chef). Results showed that, when primed to say an ungrammatical that, speakers were slower to start to speak. Because the that-trace constraint applies selectively to certain configurations of long-distance dependencies, this suggests that the grammatical details of the long-distance dependency are already planned before speakers start to speak the sentences involving long-distance dependencies. I propose a formal model that explains how speakers plan long-distance dependencies in advance of speaking them while also managing the cognitive pressure to speak sentences incrementally.