This Thesis Has Been Submitted in Fulfilment of the Requirements for a Postgraduate Degree (E.G

This thesis has been submitted in fulfilment of the requirements for a postgraduate degree (e.g. PhD, MPhil, DClinPsychol) at the University of Edinburgh. Please note the following terms and conditions of use: • This work is protected by copyright and other intellectual property rights, which are retained by the thesis author, unless otherwise stated. • A copy can be downloaded for personal non-commercial research or study, without prior permission or charge. • This thesis cannot be reproduced or quoted extensively from without first obtaining permission in writing from the author. • The content must not be changed in any way or sold commercially in any format or medium without the formal permission of the author. • When referring to this work, full bibliographic details including the author, title, awarding institution and date of the thesis must be given. PHONETICBIASESANDSYSTEMICEFFECTSINCooperation, Social Selection, and Language Change: An Experimental THEACTUATIONOFSOUNDCHANGE Investigation of Language Divergence Márton Sóskuthy Gareth Roberts I V N E R U S E I T H Y T O H F G E R D I N B U A thesis submitted in fulfilment of requirements for the degree of A thesis submitted inDoctor fulfilment of ofPhilosophy requirements for the degree of DOCTOROFPHILOSOPHY to Linguistics and English Language to Linguistics and English Language School of Philosophy, Psychology and Language Sciences School of Philosophy, Psychology and Language Sciences University of Edinburgh UNIVERSITY of EDINBURGH 2010 March 2013 DECLARATION I hereby declare that this thesis is of my own composition, and that it con- tains no material previously submitted for the award of any other degree. The work reported in this thesis has been executed by myself, except where due acknowledgement is made in the text. Márton Sóskuthy CONTENTS declaration i • abstract vii • acknowledgements xi • 1 introduction 1 • 2 background 10 • 2.1 Defining sound change 11 2.2 The actuation problem 13 2.3 Bias-based models 17 2.3.1 The leap model 17 2.3.2 The nudge model 24 2.4 Functionalist models 26 2.5 Sociolinguistic models 32 2.6 The suggested solution 34 3 theoretical assumptions 37 • 3.1 Probabilistic category representations 39 3.2 Category-based perception and production 45 3.2.1 Alternatives to the category-based view 45 3.2.2 Evidence for sound categories 49 3.3 The continuous update of categories 60 3.4 Phonetic biases 68 3.5 The filtering listener 74 3.6 Summary 80 iv 4 modelling sound change 82 • 4.1 The structure of the simulations 85 4.1.1 Category representations and sampling 86 4.1.2 Modelling the effects of phonetic biases 93 4.1.3 Category update and ambiguity 97 4.1.4 Summary of simulation architecture 101 4.2 Comparing prototype and exemplar models 101 4.2.1 Convergence towards the bias 102 4.2.2 Ambiguity-driven dispersion 108 4.2.3 Summary 114 4.3 Single and multi-agent simulations 115 4.4 Conclusions 120 5 a systemic view of sound change 123 • 5.1 Adaptive landscapes in sound change 124 5.2 Simulating complex sound systems 130 5.2.1 An example simulation 131 5.2.2 An alternative simulation framework 137 5.2.3 Exploring the adaptive landscape 141 5.3 Why sounds don’t change 153 5.4 Why sounds change 158 5.5 The social aspects of sound change 169 5.6 Summary 174 6 lexical factors in contextual effects 176 • 6.1 Sub-distributions within categories 181 6.2 The voicing effect 191 6.3 Simulating the behaviour of sub-distributions 199 6.3.1 Modelling sub-distributions 200 6.3.2 The separation of sub-distributions 205 6.3.3 Predicting the effect of bias proportion 211 6.4 An empirical study 217 6.4.1 Estimating bias proportion from corpus data 218 6.4.2 The production experiment 220 6.5 Conclusions 228 v 7 conclusions 231 • a appendix: variance inflation 234 • b appendix: the observed distribution 238 • c appendix: target locations 241 • bibliography 245 • ABSTRACT This thesis investigates the role of phonetic biases and systemic effects in the actuation of sound change through computer simulations and experimental methods. Phonetic biases are physiological and psychoacoustic constraints on speech. One example is vowel undershoot: vowels sometimes fail to reach their phonetic targets due to limitations on the speed of the articulators. Phonetic biases are often paralleled by phonological patterns. For instance, many languages exhibit vowel reduction, a phonologised version of undershoot. To account for these parallels, a number of researchers have proposed that phonetic biases are the causal drive behind sound change. Although this proposal seems to solve the problem of actuation, its success is only apparent: while it might be able to explain situations where sound change occurs, it cannot easily explain the lack of sound change, that is, stasis. Since stability in sound systems seems to be the rule rather than the exception, the bias-based approach cannot provide an adequate account of their diachronic development on its own. The problem of bias-based accounts stems from their focus on changes affect- ing individual sound categories, and their neglect of system-wide interactions. The factors that affect speech production and perception define an adaptive landscape. The development of sound systems follows the topology of this landscape. When only a single category is investigated, it is easy to take an overly simplistic view of this landscape, and assume that phonetic biases are the only relevant factor. It is natural that the predicted outcomes will be simple and de- terministic if such an approach is adopted. However, when we look at an entire sound system, other pressures such as contrast maintenance also become relevant, and the range of possible outcomes is much more diverse. Phonetic biases can still skew the adaptive landscape towards themselves, making phonetically natural outcomes more likely. However, their effects will often be countered by other pressures, which means that they will not be satisfied in every case. viii Sound systems move towards peaks in the adaptive landscape, or local optima, where the different pressures balance each other out. As a result, the system-based approach predicts stability. This stability can be broken by changes in the pressures that define the adaptive landscape. For instance, an increase or a decrease in functional load or a change in lexical distributions can create a situation where the sound system is knocked out of an equilibrium and starts evolving towards a new stable state. In essence, the adaptive landscape can create a moving target for the sound system. This ensures that both stability and change are observed. Therefore, this account makes realistic predictions with respect to the actuation problem. This argument is developed through a series of computer simulations that follow changes in artificial sound systems. All of these simulations are based on four theoretical assumptions: (i) speech production and perception are based on probabilistic category representations; (ii) these category representations are subject to continuous update throughout the lifetime of an individual; (iii) speech production and perception are affected by low-level universal phonetic biases; and (iv) category update is inhibited in cases where too many am- biguous tokens are produced due to category overlap. Special care is taken to anchor each of these assumptions in empirical results from a variety of fields including phonetics, sociolinguistics and psycholinguistics. Moreover, in order to show that the results described above follow directly from these theoretical assumptions and not other aspects of these models, the thesis demonstrates that exemplar and prototype models produce the same dynamics with respect to the observations above, and that the number of speakers in the model also does not have a significant influence on the outcomes. Much of the thesis focuses on rather abstract properties of simulated systems, which are difficult to test in a systematic way. The last chapter complements this by presenting a concrete example, which shows how the simulations can be linked to empirical data. Specifically, I look at the effect of lexical factors on the strength of contextual effects in sound categories, using the example of the voicing effect, whereby vowels are longer before voiced obstruents than they are before voiceless ones. The simulations implemented in this chapter predict a larger effect in cases where a given vowel category occurs equally frequently in voiced and voiceless environments, and a smaller difference where one of the ix environments dominates the lexical distribution of the vowel. This prediction is borne out in a small cross-linguistic production experiment looking at voicing- conditioned vowel length patterns in French, Hungarian and English. Although this is only one of many predictions that fall out of the theory of sound change developed in this thesis, the success of this experiment is a strong indication that the research questions it brings into focus are worth investigating. ACKNOWLEDGEMENTS There are many people who helped me in writing this thesis either directly or indirectly. First of all, I would like to thank Patrick Honeybone, my main supervisor. From the moment I decided to apply to the University of Edinburgh to the very end of the writing process, Patrick was an invaluable source of help and support. He is a brilliant supervisor who helped me turn my ideas into a thesis without ever making me feel pressured or uncomfortable. It was a real pleasure to work with him. James Kirby and Simon Kirby, my other two supervisors, have also contributed greatly to this project. James’ ideas on modelling sound change have had an important influence on my own work, and his suggestions inspired me to articulate my arguments as clearly as possible.

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