Gradience in Grammar

Gradience in Grammar Experimental and Computational Aspects of Degrees of Grammaticality Frank Keller V N I E R U S E I T H Y T O H F G E R D I N B U PhD University of Edinburgh 2000 Abstract This thesis deals with gradience in grammar, i.e., with the fact that some linguistic structures are not fully acceptable or unacceptable, but receive gradient linguistic judgments. The importance of gradient data for linguistic theory has been recognized at least since Chomsky’s Logical Structure of Linguistic Theory. However, systematic empirical studies of gradience are largely absent, and none of the major theoretical frameworks is designed to account for gradient data. The present thesis addresses both questions. In the experimental part of the thesis (Chapters 3–5), we present a set of magnitude estimation experiments investigating gradience in grammar. The experiments deal with unaccusativity/unergativity, extraction, binding, word order, and gapping. They cover all major modules of syntactic theory, and draw on data from three languages (English, German, and Greek). In the theoretical part of thesis (Chapters 6 and 7), we use these experimental results to motivate a model of gradience in grammar. This model is a variant of Optimality Theory, and explains gradience in terms of the competition of ranked, violable linguistic constraints. The experimental studies in this thesis deliver two main results. First, they demonstrate that an experimental investigation of gradient phenomena can advance linguistic theory by uncovering acceptability distinctions that have gone unnoticed in the theoretical literature. An experimental approach can also settle data disputes that result from the informal data collection techniques typically employed in theoretical linguistics, which are not well-suited to investigate the behavior of gradient linguistic data. Second, we identify a set of general properties of gradient data that seem to be valid for a wide range of syntactic phenomena and across languages. (a) Linguistic constraints are ranked, in the sense that some constraint violations lead to a greater degree of unacceptability than others. (b) Constraint violations are cumulative, i.e., the degree of unacceptability of a structure increases with the number of constraints it violates. (c) Two constraint types can be distinguished experimentally: soft constraints lead to mild unacceptability when violated, while hard constraint violations trigger serious unacceptability. (d) The hard/soft distinction can be diagnosed by testing for effects from the linguistic context; context effects only occur for soft constraints; hard constraints are immune to contextual variation. (e) The soft/hard distinction is crosslinguistically stable. In the theoretical part of the thesis, we develop a model of gradient grammaticality that borrows central concepts from Optimality Theory, a competition-based grammatical framework. We propose an extension, Linear Optimality Theory, motivated by our experimental results on constraint ranking and the cumulativity of violations. The core assumption of our 3 4 model is that the relative grammaticality of a structure is determined by the weighted sum of the violations it incurs. We show that the parameters of the model (the constraint weights), can be estimated using the least square method, a standard model fitting algorithm. Furthermore, we prove that standard Optimality Theory is a special case of Linear Optimality Theory. To test the validity of Linear Optimality Theory, we use it to model data from the experimental part of the thesis, including data on extraction, gapping, and word order. For all data sets, a high model fit is obtained and it is demonstrated that the model’s predictions generalize to unseen data. On a theoretical level, our modeling results show that certain properties of gradient data (the hard/soft distinction, context effects, and crosslinguistic effects) do not have to be stipulated, but follow from core assumptions of Linear Optimality Theory. Acknowledgements I am grateful to my supervisors Mark Steedman, Antonella Sorace, Matt Crocker, and Mats Rooth for continuous support and advice regarding the work reported in this thesis. Also, I would like to thank the members of my examination committee, Ellen Bard, Ewan Klein, Mar- tin Pickering, and Hans Uszkoreit, for criticism and feedback on my research. The following people have provided valuable comments: Dora Alexopoulou, Ash Asudeh, Paul Boersma, Martin Corley, Alex Heneveld, Vasilios Karaiskos, Bob Ladd, Maria Lapata, Scott McDonald, Ineke Mennen, Paul Smolensky, Simone Teufel, and Jesse Tseng. Of course, the people on this list will not necessarily agree with all the claims made in this thesis, and the responsibility for any remaining errors is mine. I have received important feedback when presenting my work at the universities of Potsdam, Saarbrücken, and Tübingen, and at the following conferences: Amlap-97, Amlap-99, CLS-98, Cogsci-00, and DGfS-99. Finally, I would like to thank the numerous subjects who participated in the experiments reported in this thesis. The financial support of DAAD, ESRC, and Studienstiftung is gratefully acknowledged. 5 Declaration I declare that this thesis was composed by myself and that the work contained therein is my own, except where explicitly stated otherwise in the text. (Frank Keller) 7 Contents 1 Introduction 17 1.1CentralClaims.................................. 17 1.2MotivationforInvestigatingGradience...................... 18 1.2.1 TheoreticalRelevanceofGradientData................. 18 1.2.2 Empirical Properties of Gradient Data . ............... 19 1.2.3 GradientDataandContext........................ 20 1.2.4 ModelingGradientData......................... 21 1.3OverviewoftheThesis.............................. 23 1.4CollaborationsandPublishedWork....................... 24 2 Background 25 2.1 Introduction .................................... 25 2.2 Acceptability Judgments and Linguistic Theory . ............... 26 2.2.1 Judgments as Evidence for Linguistic Theory .............. 26 2.2.2 CompetenceandPerformance...................... 28 2.3 Factors Influencing Acceptability Judgments ................... 30 2.3.1 Measurement Scales . .......................... 30 2.3.2 Instructions................................ 32 2.3.3 Subject-RelatedFactors......................... 33 2.3.4 Task-RelatedFactors........................... 34 2.4 Eliciting Reliable Acceptability Judgments .................... 34 2.4.1 Materials................................. 35 2.4.2 Procedure................................. 36 2.4.3 Evaluation................................ 37 2.5MagnitudeEstimation............................... 38 2.6 An Introduction to Optimality Theory . .................... 39 2.7Conclusions.................................... 41 9 10 Contents 3 Gradient Grammaticality out of Context 43 3.1 Introduction . ................................... 43 3.1.1 Constraints................................ 44 3.1.2 ConstraintRanking............................ 45 3.1.3 ConstraintTypes............................. 45 3.1.4 ConstraintInteraction........................... 46 3.1.5 Coverage................................. 46 3.1.6 Acceptability Marks . ........................ 47 3.2 Experiment 1: Effect of Verb Class on Unaccusativity and Unergativity . 47 3.2.1 Background . .............................. 48 3.2.2 Introduction . .............................. 55 3.2.3 Predictions................................ 55 3.2.4 Method.................................. 56 3.2.5 Results.................................. 60 3.2.6 Discussion................................ 64 3.2.7 Conclusions................................ 65 3.3 Experiment 2: Effect of Animacy and Telicity on Unaccusativity and Unergativity 65 3.3.1 Background . .............................. 66 3.3.2 Introduction . .............................. 68 3.3.3 Predictions................................ 69 3.3.4 Method.................................. 69 3.3.5 Results.................................. 71 3.3.6 Discussion................................ 75 3.3.7 Conclusions................................ 76 3.4 Experiment 3: Effect of Telicity on Unaccusativity and Unergativity ...... 77 3.4.1 Introduction . .............................. 77 3.4.2 Predictions................................ 78 3.4.3 Method.................................. 79 3.4.4 Results.................................. 80 3.4.5 Discussion................................ 82 3.4.6 Conclusions................................ 83 3.5Experiment4:ExtractionfromPictureNPs................... 84 3.5.1 Background . .............................. 85 3.5.2 Introduction . .............................. 87 3.5.3 Predictions................................ 87 3.5.4 Method.................................. 89 3.5.5 Results.................................. 90 3.5.6 Discussion................................ 94 Contents 11 3.5.7 Conclusions................................ 95 3.6 Experiment 5: Exempt Anaphors and Picture NPs . ............... 96 3.6.1 Background ................................ 96 3.6.2 Introduction ................................ 98 3.6.3 Predictions................................ 99 3.6.4 Method..................................100 3.6.5 Results..................................101 3.6.6 Discussion................................106 3.6.7 Conclusions................................108 3.7 Experiment 6: Effect of Case and Pronominalization on Word Order . ....108 3.7.1 Background ................................109

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