Relative clause avoidance: Evidence for a structural parsing principle q Adrian Staub a,⇑ , Francesca Foppolo b , Caterina Donati c , Carlo Cecchetto b,d a Department of Psychological and Brain Sciences, University of Massachusetts Amherst, United States b Department of Psychology, University of Milan-Bicocca, Italy c Laboratoire de Linguistique Formelle, Université Paris 7/CNRS, France d Structures Formelles du Langage, Université Paris 8/CNRS, France article info Article history: Received 15 April 2017 Revision received 11 September 2017 Available online 23 September 2017 Keywords: Sentence processing Eye movements Relative clauses Long distance dependencies abstract Three eye movement experiments investigated the processing of the syntactic ambiguity in strings such as the information that the health department provided, where the that-clause can be either a relative clause (RC) or the start of a nominal complement clause (CC; the information that the health department provided a cure). The experiments tested the prediction that comprehenders should avoid the RC analysis because it involves an unforced filler-gap dependency. Readers showed difficulty upon disambiguation toward the RC analysis, and showed facilitated processing of the ambiguous material itself when the CC analysis was available; both patterns suggest rapid initial adoption of the CC analysis in preference to the RC analysis. The strength of the bias of a specific head noun (e.g., information) to appear with a CC did not modulate these effects, nor were these effects reliably modulated by the tendency of an ambiguous string to be completed off-line as a CC or an RC. These results add to the evidence that structural principles guide the processing of filler-gap dependencies. Ó 2017 Elsevier Inc. All rights reserved. Introduction The comprehension of filler-gap dependencies has long been a central topic in sentence processing research (e.g., Clifton & Frazier, 1989; Fodor, 1978). These are structures in which an ele- ment (the filler, in psycholinguistic terminology) is displaced with respect to the location at which it receives its thematic role (the gap). In syntactic theories that posit movement, the filler is ana- lyzed as having moved from the gap site, which contains a move- ment trace (e.g. Chomsky, 1981). In (1) and (2), filler-gap dependencies appear in the context of a wh-question and a relative clause, respectively. (1) Which dog did the family choose ____ ? (2) The family chose the dog that they visited ____ on Wednesday. The great majority of research on this topic has focused on process- ing of structures in which the filler appears to the left of the corre- sponding gap site (as in (1) and (2)), and has addressed questions about how, in the course of incremental processing, the parser iden- tifies the site of the gap once a filler has been identified. One impor- tant conclusion is that incremental parsing appears to respect grammatical constraints as to the location of the gap; the parser does not posit a gap within a syntactic ’island’ (Ross, 1967), namely a syntactic domain (e.g., adjunct clauses) where a gap cannot occur (e.g., Phillips, 2006; Traxler & Pickering, 1996). A second important conclusion, however, is that the parser appears to posit a gap in any grammatically licit site that it encounters, as soon as such a site becomes apparent in the course of incremental processing. This process has come to be known as ’active gap filling’, and the corre- sponding parsing strategy as the Active Filler Strategy (Clifton & Frazier, 1989; Frazier & Clifton, 1989). There are multiple lines of evidence for active gap filling. First, processing difficulty ensues when a potential gap site turns out to be occupied by another element. This phenomenon, known as a filled gap effect, was first demonstrated by Stowe (1986), and is illustrated in (3): (3) Which dog did the family choose a leash for _____ at the pet store? https://doi.org/10.1016/j.jml.2017.09.003 0749-596X/Ó 2017 Elsevier Inc. All rights reserved. q Thanks to Kirk Goddard, Sophia Dodge, Atreyi Mukherji, Sinthema Roy, Wesley Albright, Chhing Tiv, Jessica Tin, and Audrey O’Neill for assistance with data collection. Thanks also for helpful comments from audiences at the 2016 CUNY Conference on Human Sentence Processing at the University of Florida, and colloquium audiences at University College London and Bournemouth University. Thanks to Chuck Clifton for insightful comments on an earlier draft of this manuscript. ⇑ Corresponding author at: Department of Psychological and Brain Sciences, University of Massachusetts, 430 Tobin Hall, Amherst, MA 01003, United States. E-mail address: astaub@psych.umass.edu (A. Staub). Journal of Memory and Language 98 (2018) 26–44 Contents lists available at ScienceDirect Journal of Memory and Language journal homepage: www.elsevier.com/locate/jml