Publications

Abstract

Artificial lexicons have previously been used to examine the time course of the learning and recognition of spoken words, the role of segment type in word learning, and the integration of context during spoken word recognition. However, in all of these studies the experimenter determined the frequency and order of the words to be learned. In three experiments, we asked whether adult learners choose to listen to novel words in a particular order based on their acoustic similarity. We use a new paradigm for learning an artificial lexicon in which the learner, rather than the experimenter, determines the order and frequency of exposure to items. We analyze both the proportions of selections and the temporal clustering of subjects' sampling of lexical neighborhoods during training as well as their performance during repeated testing phases (accuracy and reaction time) to determine the time course of learning these neighborhoods. In the first experiment, subjects sampled the high and low density neighborhoods randomly in early learning, and then over-sampled the high density neighborhood until test performance on both neighborhoods reached asymptote. A second experiment involved items similar to the first, but also neighborhoods that are not fully revealed at the start of the experiment. Subjects adjusted their training patterns to focus their selections on neighborhoods of increasing density was revealed; evidence of learning in the test phase was slower to emerge than in the first experiment, impaired by the presence of additional sets of items of varying density. Crucially, in both the first and second experiments there was no effect of dense vs. sparse neighborhood in the accuracy results, which is accounted for by subjects’ over-sampling of items from the dense neighborhood. The third experiment was identical in design to the second except for a second day of further training and testing on the same items. Testing at the beginning of the second day showed impaired, not improved, accuracy, except for the consistently dense items. Further training, however, improved accuracy for some items to above Day 1 levels. Overall, these results provide a new window on the time-course of learning an artificial lexicon and the role that learners’ implicit preferences, stemming from their self-selected experience with the entire lexicon, play in learning highly confusable words.

Abstract

Children learn their mother tongue spontaneously and effortlessly through communicative interaction with their environment; they do not have to be taught explicitly or learn how to learn first. The ambient language to which children are exposed, however, is highly variable and arguably deficient with regard to the learning target. Nonetheless, most normally developing children learn their native language rapidly and with ease. To explain this accomplishment, many theories of acquisition posit innate constraints on learning, or even a biological endowment for language which is specific to language. Usage-based theories, on the other hand, place more emphasis on the role of experience and domain-general learning mechanisms than on innate language-specific knowledge. But languages are lexically open and combinatorial in structure, so no amount of experience covers their expressivity. Usage-based theories therefore have to explain how children can generalize the properties of their linguistic input to an adult-like grammar. In this thesis I provide an explicit computational mechanism with which usage-based theories of language can be tested and evaluated. The focus of my work lies on complex syntax and the human ability to form sentences which express more than one proposition by means of relativization. This `capacity for recursion' is a hallmark of an adult grammar and, as some have argued, the human language faculty itself. The manuscript is organized as follows. In the second chapter, I give an overview of results that characterize the properties of neural networks as mathematical objects and review previous attempts at modelling the acquisition of complex syntax with such networks. The chapter introduces the conceptual landscape in which the current work is located. In the third chapter, I argue that the construction and use of meaning is essential in child language acquisition and adult processing. Neural network models need to incorporate this dimension of human linguistic behavior. I introduce the Dual-path model of sentence production and syntactic development which is able to represent semantics and learns from exposure to sentences paired with their meaning (cf. Chang et al. 2006). I explain the architecture of this model, motivate critical assumptions behind its design, and discuss existing research using this model. The fourth chapter describes and compares several extensions of the basic architecture to accommodate the processing of multi-clause utterances. These extensions are evaluated against computational desiderata, such as good learning and generalization performance and the parsimony of input representations. A single-best solution for encoding the meaning of complex sentences with restrictive relative clauses is identified, which forms the basis for all subsequent simulations. Chapter five analyzes the learning dynamics in more detail. I first examine the model's behavior for different relative clause types. Syntactic alternations prove to be particularly difficult to learn because they complicate the meaning-to-form mapping the model has to acquire. In the second part, I probe the internal representations the model has developed during learning. It is argued that the model acquires the argument structure of the construction types in its input language and represents the hierarchical organization of distinct multi-clause utterances. The juice of this thesis is contained in chapters six to eight. In chapter six, I test the Dual-path model's generalization capacities in a variety of tasks. I show that its syntactic representations are sufficiently transparent to allow structural generalization to novel complex utterances. Semantic similarities between novel and familiar sentence types play a critical role in this task. The Dual-path model also has a capacity for generalizing familiar words to novel slots in novel constructions (strong semantic systematicity). Moreover, I identify learning conditions under which the model displays recursive productivity. It is argued that the model's behavior is consistent with human behavior in that production accuracy degrades with depth of embedding, and right-branching is learned faster than center-embedding recursion. In chapter seven, I address the issue of learning complex polar interrogatives in the absence of positive exemplars in the input. I show that the Dual-path model can acquire the syntax of these questions from simpler and similar structures which are warranted in a child's linguistic environment. The model's errors closely match children's errors, and it is suggested that children might not require an innate learning bias to acquire auxiliary fronting. Since the model does not implement a traditional kind of language-specific universal grammar, these results are relevant to the poverty of the stimulus debate. English relative clause constructions give rise to similar performance orderings in adult processing and child language acquisition. This pattern matches the typological universal called the noun phrase accessibility hierarchy. I propose an input-based explanation of this data in chapter eight. The Dual-path model displays this ordering in syntactic development when exposed to plausible input distributions. But it is possible to manipulate and completely remove the ordering by varying properties of the input from which the model learns. This indicates, I argue, that patterns of interference and facilitation among input structures can explain the hierarchy when all structures are simultaneously learned and represented over a single set of connection weights. Finally, I draw conclusions from this work, address some unanswered questions, and give a brief outlook on how this research might be continued.

Abstract

This dissertation is an ethnographic study of race and other forms of social categorization as approached through the discourse of the indigenous Chachi people of northwestern lowland Ecuador and their Afro-descendant neighbors. It combines the ethnographic methods of social anthropology with the methods of descriptive linguistics, letting social questions about racial formation guide linguistic inquiry. It provides new information about the largely unstudied indigenous South American language Cha’palaa, and connects that information about linguistic form to problems of the study of race and ethnicity in Latin America. Individual descriptive chapters address how the Cha’palaa number system is based on collectivity rather than plurality according to an animacy hierarchy that codes only human and human-like social collectivities, how a nominal set of ethnonyms linked to Chachi oral history become the recipients of collective marking as human collectivities, how those collectivities are co-referentially linked to speech participants through the deployment of the pronominal system, and how the multi-modal resource of gesture adds to these rich resources supplied by the spoken language for the expression of social realities like race. The final chapters address Chachi and Afrodescendant discourses in dialogue with each other and examine naturally occurring speech data to show how the linguistic forms described in previous chapters are used in social interaction. The central argument advances a position that takes the socially constructed status of race seriously and considers that for such constructions to exist as more abstract macro-categories they must be constituted by instances of social interaction, where elements of the social order are observable at the micro-level. In this way localized articulations of social categories become vehicles for the broader circulation of discourses structured by a history of racialized social inequality, revealing the extreme depth of racialization in human social conditioning. This dissertation represents a contribution to the field of linguistic anthropology as well as to descriptive linguistics of South American languages and to critical approaches to race and ethnicity in Latin America.

Abstract

Whitesands is an under-described language of southern Vanuatu, and this thesis presents Whitesands-specific data based on primary in-situ field research. The thesis addresses the distinction of noun and verb word classes in the language. It claims that current linguistic syntax theory cannot account for the argument structure of canonical object-denoting roots. It is shown that there are distinct lexical noun and verb classes in Whitesands but this is only a weak dichotomy. Stronger is the NP and VP distinction, and this is achieved by employing a new theoretical approach that proposes functional categories and their selection of complements as crucial tests of distinction. This approach contrasts with previous analyses of parts of speech in Oceanic languages and cross-linguistically. It ultimately explains many of the syntactic phenomena seen in the language family, including the above argument assignment dilemma, the alienable possession of nouns with classifiers and also the nominalisation processes.

Abstract

This thesis is about whether language affects thinking. It deals with the linguistic relativity hypothesis, which proposes that the language we speak influences the way we think. This hypothesis is investigated in the domain of caused motion (e.g., ‘The man rolled the tyre into the garage’), by looking at Spanish and Swedish, two languages that show striking differences in how motion events are encoded. The thesis consists of four studies. The first two focus on native speakers of Spanish and Swedish. Study I compares how Spanish and Swedish speakers describe the same set of caused motion events, directing the spotlight at how variable the descriptions are in each language. The results confirm earlier findings from semantic typology regarding the dominant ways of expressing the events in each language: Spanish behaves like a verb-framed language and Swedish like a satellite-framed language (Talmy, 2000). Going beyond previous findings, the study demonstrates—using the tools of entropy and Monte Carlo simulations—that there is markedly more variability in Spanish than in Swedish descriptions. Study II tests whether differences in how Spanish and Swedish speakers describe caused motion events are reflected in how they think about such events. Using a novel similarity arrangement task, it is found that Spanish and Swedish speakers partly differ in how they represent caused motion events if they can access language during the task. However, the differences disappear when the possibility to use language is momentarily blocked by an interference task. The last two studies focus on Swedish learners of Spanish as a second language (L2). Study III explores how Swedish learners (compared to native Spanish speakers) adapt their Spanish motion descriptions to recently encountered input. Using insights from the literature on structural priming, we find that Swedish learners initially expect to encounter in their L2, Spanish, those verb types that are typical in Swedish (manner verbs like ‘roll’) but that, with increasing proficiency, their expectations become increasingly attuned to the typical Spanish pattern of using path verbs (like ‘enter’). These expectations are reflected in the way L2 learners adapt their own production to the Spanish input. Study IV asks whether recent linguistic experience in an L2 can affect how L2 learners think about motion events. It is found that encountering motion descriptions in the L2 that emphasize different types of information (path or manner) leads L2 speakers to perceive similarity along different dimensions in a subsequent similarity arrangement task. Taken together, the thesis argues that the study of the relation between language and thought affords more valuable insights when not posed as an either-or question (i.e., does language affect thought or not?). In this spirit, the thesis contributes to the wider aim of investigating the conditions under which language does or does not affect thought and explores what the different outcomes tell us about language, thought, and the intricate mechanisms that relate them.

Abstract

Many Mayan languages make use of a special dependent verb form (the Agent Focus, or AF verb form), which alternates with the normal transitive verb form (the synthetic verb form) of main clauses when the subject of a transitive verb is focused, questioned or relativized. It has been a centerpiece of research in Mayan morphosyntax over the last forty years, due to its puzzling formal and distributional properties. In this dissertation I show how a usage-oriented approach to the phenomenon can provide important insights into this area of grammar which resists any categorical explanation. I propose that the historical origins of these special verb forms can be traced to the emergence of head marking. Drawing on cross-linguistic and historical data, I argue that the special verbs that occur in A-bar dependencies in Yucatec and a range of head-marking languages are byproducts of the frequency-sensitive gramaticalization process by which independent pronouns become pronominal inflection on verbs. I show that the relatively low frequency of adjacent pronoun-verb combinations in extraction contexts (where gaps are more frequent than resumptive pronouns) can give rise to asymmetric patterns of pronoun grammaticalization, and thus lead to the emergence of these morphological alternations. The asymmetric frequency distributions of gaps and RPs (within and across languages) in turn can be explained by processing preferences. I present three experiments which show that Yucatec speakers are more likely to use the resumptive verb form in embedded environments, and where the antecedent is indefinite. Specifically, these studies indicate the need to bring discourse-level processing principles into the account of what have often been taken to be autonomously sentence-internal phenomena: factors such as distance and the referential salience of the antecedent have been shown to influence referential form choice in discourse, suggesting that the same cognitive principles lie behind both types of variation. More generally, the Yucatec studies demonstrate that production preferences in Yucatec relative clauses reflect patterns of RP/gap distributions that have been attested across grammars. The Highest Subject Restriction (the ban on subject RPs in local dependencies), which is apparently a categorical constraint in many languages, is reflected probabilistically in Yucatec in terms of production preferences. The definiteness restriction (RPs are obligatory with indefinite antecedents), which has been reported categorically in other languages, is also visible probabilistically in Yucatec production. This lends some statistically robust support to the view that typological patterns can arise via the conventionalization of processing preferences.

Abstract

Sarah Schimke onderzocht hoe mensen die op volwassen leeftijd naar een ander land verhuizen de taal van dit land leren, ook zonder veel taalinstructie te krijgen. Twee groepen werden onderzocht: Turkse immigranten in Frankrijk en Turkse immigranten in Duitsland. De resultaten laten zien dat volwassen leerlingen in het begin van het verwervingsproces een gemakkelijkere variatie van de doeltaal creëren. Er worden wel woorden van de doeltaal verworven en gebruikt, maar er wordt een gesimplificeerde grammatica toegepast. In het bijzonder gebruiken leerlingen in deze fase geen finietheid, dus geen morfologische variaties van werkwoorden. Schimke toont aan dat als finietheid wordt verworven, dit de grammatica van de leerlingen sterk verandert en dat deze veel sterker op de doeltaalgrammatica begint te lijken. Ook toont ze aan dat dit proces door karakteristieken van de doeltaal, zoals de woordvolgorde en de complexiteit van de morfologie, wordt beïnvloed