Linguistics Theses and Dissertations

Permanent URI for this collectionhttp://hdl.handle.net/1903/2787

Browse

End date: 2019Subject: search.filters.subject.Cognitive psychology

Search Results

Now showing 1 - 7 of 7
  • Thumbnail Image
    Item
    Information and Incrementality in Syntactic Bootstrapping
    (2015) White, Aaron Steven; Hacquard, Valentine; Linguistics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Some words are harder to learn than others. For instance, action verbs like "run" and "hit" are learned earlier than propositional attitude verbs like "think" and "want." One reason "think" and "want" might be learned later is that, whereas we can see and hear running and hitting, we can't see or hear thinking and wanting. Children nevertheless learn these verbs, so a route other than the senses must exist. There is mounting evidence that this route involves, in large part, inferences based on the distribution of syntactic contexts a propositional attitude verb occurs in---a process known as "syntactic bootstrapping." This fact makes the domain of propositional attitude verbs a prime proving ground for models of syntactic bootstrapping. With this in mind, this dissertation has two goals: on the one hand, it aims to construct a computational model of syntactic bootstrapping; on the other, it aims to use this model to investigate the limits on the amount of information about propositional attitude verb meanings that can be gleaned from syntactic distributions. I show throughout the dissertation that these goals are mutually supportive. In Chapter 1, I set out the main problems that drive the investigation. In Chapters 2 and 3, I use both psycholinguistic experiments and computational modeling to establish that there is a significant amount of semantic information carried in both participants' syntactic acceptability judgments and syntactic distributions in corpora. To investigate the nature of this relationship I develop two computational models: (i) a nonnegative model of (semantic-to-syntactic) projection and (ii) a nonnegative model of syntactic bootstrapping. In Chapter 4, I use a novel variant of the Human Simulation Paradigm to show that the information carried in syntactic distribution is actually utilized by (simulated) learners. In Chapter 5, I present a proposal for how to solve a standing problem in how syntactic bootstrapping accounts for certain kinds of cross-linguistic variation. And in Chapter 6, I conclude with future directions for this work.
  • Thumbnail Image
    Item
    Bayesian Model of Categorical Effects in L1 and L2 Speech Processing
    (2014) Kronrod, Yakov; Feldman, Naomi; Linguistics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    In this dissertation I present a model that captures categorical effects in both first language (L1) and second language (L2) speech perception. In L1 perception, categorical effects range between extremely strong for consonants to nearly continuous perception of vowels. I treat the problem of speech perception as a statistical inference problem and by quantifying categoricity I obtain a unified model of both strong and weak categorical effects. In this optimal inference mechanism, the listener uses their knowledge of categories and the acoustics of the signal to infer the intended productions of the speaker. The model splits up speech variability into meaningful category variance and perceptual noise variance. The ratio of these two variances, which I call Tau, directly correlates with the degree of categorical effects for a given phoneme or continuum. By fitting the model to behavioral data from different phonemes, I show how a single parametric quantitative variation can lead to the different degrees of categorical effects seen in perception experiments with different phonemes. In L2 perception, L1 categories have been shown to exert an effect on how L2 sounds are identified and how well the listener is able to discriminate them. Various models have been developed to relate the state of L1 categories with both the initial and eventual ability to process the L2. These models largely lacked a formalized metric to measure perceptual distance, a means of making a-priori predictions of behavior for a new contrast, and a way of describing non-discrete gradient effects. In the second part of my dissertation, I apply the same computational model that I used to unify L1 categorical effects to examining L2 perception. I show that we can use the model to make the same type of predictions as other SLA models, but also provide a quantitative framework while formalizing all measures of similarity and bias. Further, I show how using this model to consider L2 learners at different stages of development we can track specific parameters of categories as they change over time, giving us a look into the actual process of L2 category development.
  • Thumbnail Image
    Item
    Pragmatic enrichment in language processing and development
    (2013) Lewis, Shevaun; Phillips, Colin; Linguistics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    The goal of language comprehension for humans is not just to decode the semantic content of sentences, but rather to grasp what speakers intend to communicate. To infer speaker meaning, listeners must at minimum assess whether and how the literal meaning of an utterance addresses a question under discussion in the conversation. In cases of implicature, where the speaker intends to communicate more than just the literal meaning, listeners must access additional relevant information in order to understand the intended contribution of the utterance. I argue that the primary challenge for inferring speaker meaning is in identifying and accessing this relevant contextual information. In this dissertation, I integrate evidence from several different types of implicature to argue that both adults and children are able to execute complex pragmatic inferences relatively efficiently, but encounter some difficulty finding what is relevant in context. I argue that the variability observed in processing costs associated with adults' computation of scalar implicatures can be better understood by examining how the critical contextual information is presented in the discourse context. I show that children's oft-cited hyper-literal interpretation style is limited to scalar quantifiers. Even 3-year-olds are adept at understanding indirect requests and "parenthetical" readings of belief reports. Their ability to infer speaker meanings is limited only by their relative inexperience in conversation and lack of world knowledge.
  • Thumbnail Image
    Item
    Respecting Relations: Memory Access and Antecedent Retrieval in Incremental Sentence Processing
    (2013) Kush, Dave W; Phillips, Colin; Linguistics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    This dissertation uses the processing of anaphoric relations to probe how linguistic information is encoded in and retrieved from memory during real-time sentence comprehension. More specifically, the dissertation attempts to resolve a tension between the demands of a linguistic processor implemented in a general-purpose cognitive architecture and the demands of abstract grammatical constraints that govern language use. The source of the tension is the role that abstract configurational relations (such as c-command, Reinhart 1983) play in constraining computations. Anaphoric dependencies are governed by formal grammatical constraints stated in terms of relations. For example, Binding Principle A (Chomsky 1981) requires that antecedents for local anaphors (like the English reciprocal each other) bear the c-command relation to those anaphors. In incremental sentence processing, antecedents of anaphors must be retrieved from memory. Recent research has motivated a model of processing that exploits a cue-based, associative retrieval process in content-addressable memory (e.g. Lewis, Vasishth & Van Dyke 2006) in which relations such as c-command are difficult to use as cues for retrieval. As such, the c-command constraints of formal grammars are predicted to be poorly implemented by the retrieval mechanism. I examine retrieval's sensitivity to three constraints on anaphoric dependencies: Principle A (via Hindi local reciprocal licensing), the Scope Constraint on bound-variable pronoun licensing (often stated as a c-command constraint, though see Barker 2012), and Crossover constraints on pronominal binding (Postal 1971, Wasow 1972). The data suggest that retrieval exhibits fidelity to the constraints: structurally inaccessible NPs that match an anaphoric element in morphological features do not interfere with the retrieval of an antecedent in most cases considered. In spite of this alignment, I argue that retrieval's apparent sensitivity to c-command constraints need not motivate a memory access procedure that makes direct reference to c-command relations. Instead, proxy features and general parsing operations conspire to mimic the extension of a system that respects c-command constraints. These strategies provide a robust approximation of grammatical performance while remaining within the confines of a independently- motivated general-purpose cognitive architecture.
  • Thumbnail Image
    Item
    The Temporal Dimension of Linguistic Prediction
    (2013) Chow, Wing Yee; Phillips, Colin; Linguistics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    This thesis explores how predictions about upcoming language inputs are computed during real-time language comprehension. Previous research has demonstrated humans' ability to use rich contextual information to compute linguistic prediction during real-time language comprehension, and it has been widely assumed that contextual information can impact linguistic prediction as soon as it arises in the input. This thesis questions this key assumption and explores how linguistic predictions develop in real-time. I provide event-related potential (ERP) and reading eye-movement (EM) evidence from studies in Mandarin Chinese and English that even prominent and unambiguous information about preverbal arguments' structural roles cannot immediately impact comprehenders' verb prediction. I demonstrate that the N400, an ERP response that is modulated by a word's predictability, becomes sensitive to argument role-reversals only when the time interval for prediction is widened. Further, I provide initial evidence that different sources of contextual information, namely, information about preverbal arguments' lexical identity vs. their structural roles, may impact linguistic prediction on different time scales. I put forth a research framework that aims to characterize the mental computations underlying linguistic prediction along a temporal dimension.
  • Thumbnail Image
    Item
    Statistical Knowledge and Learning in Phonology
    (2013) Dunbar, Ewan; Idsardi, William J; Linguistics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    This thesis deals with the theory of the phonetic component of grammar in a formal probabilistic inference framework: (1) it has been recognized since the beginning of generative phonology that some language-specific phonetic implementation is actually context-dependent, and thus it can be said that there are gradient "phonetic processes" in grammar in addition to categorical "phonological processes." However, no explicit theory has been developed to characterize these processes. Meanwhile, (2) it is understood that language acquisition and perception are both really informed guesswork: the result of both types of inference can be reasonably thought to be a less-than-perfect committment, with multiple candidate grammars or parses considered and each associated with some degree of credence. Previous research has used probability theory to formalize these inferences in implemented computational models, especially in phonetics and phonology. In this role, computational models serve to demonstrate the existence of working learning/per- ception/parsing systems assuming a faithful implementation of one particular theory of human language, and are not intended to adjudicate whether that theory is correct. The current thesis (1) develops a theory of the phonetic component of grammar and how it relates to the greater phonological system and (2) uses a formal Bayesian treatment of learning to evaluate this theory of the phonological architecture and for making predictions about how the resulting grammars will be organized. The coarse description of the consequence for linguistic theory is that the processes we think of as "allophonic" are actually language-specific, gradient phonetic processes, assigned to the phonetic component of grammar; strict allophones have no representation in the output of the categorical phonological grammar.
  • Thumbnail Image
    Item
    Windows into Sensory Integration and Rates in Language Processing: Insights from Signed and Spoken Languages
    (2011) Hwang, So-One K.; Idsardi, William J.; Linguistics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    This dissertation explores the hypothesis that language processing proceeds in "windows" that correspond to representational units, where sensory signals are integrated according to time-scales that correspond to the rate of the input. To investigate universal mechanisms, a comparison of signed and spoken languages is necessary. Underlying the seemingly effortless process of language comprehension is the perceiver's knowledge about the rate at which linguistic form and meaning unfold in time and the ability to adapt to variations in the input. The vast body of work in this area has focused on speech perception, where the goal is to determine how linguistic information is recovered from acoustic signals. Testing some of these theories in the visual processing of American Sign Language (ASL) provides a unique opportunity to better understand how sign languages are processed and which aspects of speech perception models are in fact about language perception across modalities. The first part of the dissertation presents three psychophysical experiments investigating temporal integration windows in sign language perception by testing the intelligibility of locally time-reversed sentences. The findings demonstrate the contribution of modality for the time-scales of these windows, where signing is successively integrated over longer durations (~ 250-300 ms) than in speech (~ 50-60 ms), while also pointing to modality-independent mechanisms, where integration occurs in durations that correspond to the size of linguistic units. The second part of the dissertation focuses on production rates in sentences taken from natural conversations of English, Korean, and ASL. Data from word, sign, morpheme, and syllable rates suggest that while the rate of words and signs can vary from language to language, the relationship between the rate of syllables and morphemes is relatively consistent among these typologically diverse languages. The results from rates in ASL also complement the findings in perception experiments by confirming that time-scales at which phonological units fluctuate in production match the temporal integration windows in perception. These results are consistent with the hypothesis that there are modality-independent time pressures for language processing, and discussions provide a synthesis of converging findings from other domains of research and propose ideas for future investigations.