Optional that indicates production difficulty: evidence from disfluencies

Optional word omission, such as that omission in complement and relative clauses, has been argued to be driven by production pressure (rather than by comprehension). One particularly strong production-driven hypothesis states that speakers insert words to buy time to alleviate production difficulties. I present evidence from the distribution of disfluencies in non-subjectextracted relative clauses arguing against this hypothesis. While word omission is driven by production difficulties, speakers may use that as a collateral signal to addressees, informing them of anticipated production difficulties. In that sense, word omission would be subject to audience design (i.e. catering to addressees’ needs).