PDF hosted at the Radboud Repository of the Radboud University Nijmegen The following full text is a publisher's version. For additional information about this publication click this link. http://hdl.handle.net/2066/113045 Please be advised that this information was generated on 2016-05-02 and may be subject to change. Iris Hanique Mental representation and processing of reduced words in casual speech 48 Mental representation and processing of reduced words in casual speech c 2013, Iris Hanique ISBN: 978-94-6191-903-8 Printed and bound by Ipskamp Drukkers, Nijmegen Mental representation and processing of reduced words in casual speech Proefschrift ter verkrijging van de graad van doctor aan de Radboud Universiteit Nijmegen op gezag van de rector magnificus prof. mr. S.C.J.J. Kortmann, volgens besluit van het college van decanen in het openbaar te verdedigen op woensdag 13 november 2013 om 16.30 uur precies door Iris Arnolda Maria Hanique geboren op 18 augustus 1985 te Eindhoven Promotoren: Prof. dr. L. Boves Prof. dr. A. Cutler Prof. dr. M. Ernestus Manuscriptcommissie: Prof. dr. A. van den Bosch (voorzitter) Dr. R.J.J.H. van Son (Nederlands Kanker Instituut / Universiteit van Amsterdam) Prof. dr. N. Warner (Universiteit van Arizona, VS) Contents Chapter 1: Introduction 1 Psycholinguistic models . .1 Morphology . .5 Individual differences . .6 Methodology . .7 Outline . .9 Chapter 2: Processes underlying acoustic reduction: a corpus study 11 Introduction . 12 Study 1: Schwa reduction . 16 Study 2: /t/ reduction . 24 General discussion . 27 Appendix . 33 Chapter 3: Processes underlying acoustic reduction: a production experi- ment 35 Introduction . 36 Method . 37 Results and discussion for schwa . 40 Results and discussion for /t/ .......................... 42 General discussion . 44 Chapter 4: Exemplar effects in word comprehension 45 Introduction . 46 Experiment 1 . 48 Experiment 2 . 55 Experiment 3 . 57 Experiment 4 . 59 Additional analysis of all experimental data . 60 General discussion . 61 Chapter 5: The role of morphology in acoustic reduction 65 Introduction . 66 The repetition of morphemes . 68 vii Single segment affixes . 68 Morphological decomposability . 71 Word information load . 74 General discussion . 75 Chapter 6: Individual differences in the choice and pronunciation of words 79 Introduction . 80 Method . 82 Results and discussion . 87 General discussion . 96 Chapter 7: General discussion and conclusions 99 Methodology . 99 Experimental results . 103 Psycholinguistic models . 107 Conclusions . 109 English summary 111 Processes underlying acoustic reduction . 111 Morphology . 113 Individual differences . 114 Methodology . 115 General conclusions . 116 Nederlandse samenvatting 119 Reductieprocessen . 119 Morfologie . 121 Individuele verschillen . 122 Algemene conclusies . 122 References 125 Acknowledgments 135 Curriculum Vitae 137 List of Publications 139 MPI series in psycholinguistics 141 viii Introduction Chapter 1 Everyday conversational speech is characterized by extensive variation in the pro- nunciations of words. One type of variation is due to the acoustic reduction of words: words are often not produced as their full forms with all segments carefully pro- nounced, but as reduced forms with altered, shortened, or even absent segments. For instance, the English word apparently has the full form /@phE~R@ntli/, but may be pronounced as [phE~Ri] or [phE~] (Johnson, 2004). Similarly, in Dutch, the word natuurlijk ‘of course’ may be pronounced as for instance [ntyrl@k], [tyl@k], or [tyk] in- stead of /natyrl@k/ (Ernestus, 2000). These reduction phenomena occur frequently: for conversational American English, Johnson (2004) showed that in six percent of all content words at least one syllable is absent and that over sixty percent of all words deviate from their full forms. In the Ernestus Corpus of Spontaneous Dutch (Ernestus, 2000), high reduction rates have also been found, that is, over forty per- cent of words are not produced in their full form and almost twenty percent of words are missing a syllable (Schuppler, Ernestus, Scharenborg, & Boves, 2011). Already in the eighties, Mehta & Cutler (1988) showed that the comprehension of conver- sational speech makes very different demands than the comprehension of carefully articulated, read aloud speech. This dissertation investigates how speakers and lis- teners process acoustic reductions in casual Dutch. The studies in this dissertation are based on and will help improve models of speech production and speech com- prehension. In particular, they address the question how words are represented in the mental lexicon. Furthermore, these studies examine the processing of reduction phenomena by means of different quantitative and experimental methods. Psycholinguistic models Psycholinguistic models range on a continuum from purely abstractionist models to entirely exemplar-based models, and differ mostly in their assumptions about the number of lexical representations per word and the amount of detailed information stored in the mental lexicon. Abstractionist models (e.g., Chomsky & Halle, 1968; Levelt, Roelofs, & Meyer, 1999; Pinker, 1991) assume that the pronunciations of words are represented in the mental lexicon as strings of abstract phonological units, for instance, as strings of 1 Chapter 1 Introduction phonemes. The far end of the continuum is represented by abstractionist models assuming that for each word the mental lexicon stores exactly one pronunciation. Hence, the word apparently has one phonological representation, although it may be pronounced in various ways. A pronunciation that differs from the stored repre- sentation results from the application of general phonetic and phonological rules to this stored representation. During speech comprehension, these rules are reversed to map a reduced pronunciation onto the stored abstract representation. Rules may state that a given segment may be adapted or deleted in a certain phonological con- text. For instance, there may be a rule stating that schwa might be deleted in the Dutch word /x@won/ gewoon ‘just’. At a less extreme point on the continuum, abstractionist models assume that the mental lexicon stores multiple pronunciation variants for each word. According to these models, each pronunciation variant is recognized via its own abstract repre- sentation. The production of a word with absent segments may result from two types of processes. On the one hand, speakers may select a word’s full form and reduce it during articulation, which results in shortened and, in extreme cases, absent seg- ments (Browman & Goldstein, 1990). Importantly, the shortening and absence of a segment then result from the same gradient process. On the other hand, speakers may retrieve a pronunciation variant with missing segments from the mental lexicon. The missing segments are then always completely (categorically) absent. Exemplar-based models (e.g., Bybee, 2001, p. 35; Goldinger, 1998) assume the storage of all occurrences of a word that a language user has ever pronounced or heard. Most or all of these occurrences are stored in the form of exemplars, which are acoustically detailed representations. Exemplars representing the same word to- gether form one cloud. The pronunciation of a word results from the retrieval of one or the average of multiple exemplars that represent a certain pronunciation variant. The recognition of a word occurs by mapping a pronunciation onto a cloud of exemplars. Abstractionist and exemplar-based models are combined in hybrid models, located in the middle of the continuum (e.g., Goldinger, 2007; Hawkins, 2003; McLennan, Luce, & Charles-Luce, 2003; Pierrehumbert, 2002). They combine the advantages of abstractionist and exemplar-based models by assuming that words are stored with both abstract representations and exemplars. The various versions of hybrid models differ in the exact roles of the two types of representations during production and recognition, and how these representations interact. As hybrid models are currently accepted by many researchers and as the literature provides evidence for both ab- stract representations and exemplars, this dissertation is based on this type of model. Evidence for multiple representations Several studies have found support for the assumption that at least some words are represented with more than one pronunciation variant in the mental lexicon. Two studies focusing on speech comprehension report that a pronunciation variant is re- 2 Mental representation and processing of reduced words in casual speech cognized more accurately and quickly if this variant occurs more often. Pitt, Dilley, & Tat (2011) showed this for the comprehension of English words with a word-medial /t/ that was produced as [t], [R], or [P], or was absent. Ranbom & Connine (2007) showed this for the comprehension of American English words with /nt/ that are pro- nounced with a nasal flap (e.g., [dZE˜Rl] /dZEntl/ gentle). Since the variant frequencies play a role in speech comprehension, they must be represented in the mental lexi- con. The authors of the two papers assume that the frequencies are stored with the full and reduced pronunciation variants themselves. An alternative assumption is that the variant frequencies specify how often each word’s full form is subject to (a series of) reduction processes. The mental lexicon then specifies how often the full form occurs and how often all its variants occur. This latter assumption is experimentally indistinguishable from the first