“…Availability -or, ease of production of upcoming material -is known to aff ect sentence planning (Bock & Warren, 1985 ;Branigan et al, 2008 ;Brown-Schmidt & Konopka, 2008 ;Ferreira, 1996 ;Ferreira & Dell, 2000 ;Prat-Sala & Branigan, 2000 ). For example, when upcoming material is not available for production, speakers are more likely to lengthen preceding words (Fox Tree & Clark, 1997 ) or insert additional words (Clark & Fox Tree, 2002 ), including optional function words, such as optional that in English complement or relative clauses (Ferreira & Dell, 2000 ;Roland et al, 2006 ). Specifi cally, there is evidence that speakers are less likely to produce that if an object relative clause starts with a defi nite NP, compared to an indefi nite NP (Elsness, 1984 ;Jaeger & Wasow, 2006 ;Tottie, 1995 previous mention (Prince, 1981 ).…”