Statistical language learning

Theoretical arguments based on the "poverty of the stimulus" have denied a priori the possibility that abstract linguistic representations can be learned inductively from exposure to the environment, given that the linguistic input available to the child is both underdetermined and degenerate. I reassess such learnability arguments by exploring a) the type and amount of statistical information implicitly available in the input in the form of distributional and phonological cues; b) psychologically plausible inductive mechanisms for constraining the search space; c) the nature of linguistic representations, algebraic or statistical. To do so I use three methodologies: experimental procedures, linguistic analyses based on large corpora of naturally occurring speech and text, and computational models implemented in computer simulations. In Chapters 1,2, and 5, I argue that long-distance structural dependencies - traditionally hard to explain with simple distributional analyses based on ngram statistics - can indeed be learned associatively provided the amount of intervening material is highly variable or invariant (the Variability effect). In Chapter 3, I show that simple associative mechanisms instantiated in Simple Recurrent Networks can replicate the experimental findings under the same conditions of variability. Chapter 4 presents successes and limits of such results across perceptual modalities (visual vs. auditory) and perceptual presentation (temporal vs. sequential), as well as the impact of long and short training procedures. In Chapter 5, I show that generalisation to abstract categories from stimuli framed in non-adjacent dependencies is also modulated by the Variability effect. In Chapter 6, I show that the putative separation of algebraic and statistical styles of computation based on successful speech segmentation versus unsuccessful generalisation experiments (as published in a recent Science paper) is premature and is the effect of a preference for phonological properties of the input. In chapter 7 computer simulations of learning irregular constructions suggest that it is possible to learn from positive evidence alone, despite Gold's celebrated arguments on the unlearnability of natural languages. Evolutionary simulations in Chapter 8 show that irregularities in natural languages can emerge from full regularity and remain stable across generations of simulated agents. In Chapter 9 I conclude that the brain may endowed with a powerful statistical device for detecting structure, generalising, segmenting speech, and recovering from overgeneralisations. The experimental and computational evidence gathered here suggests that statistical language learning is more powerful than heretofore acknowledged by the current literature

Statistical language learning

Theoretical arguments based on the "poverty of the stimulus" have denied a priori the possibility that abstract linguistic representations can be learned inductively from exposure to the environment, given that the linguistic input available to the child is both underdetermined and degenerate. I reassess such learnability arguments by exploring a) the type and amount of statistical information implicitly available in the input in the form of distributional and phonological cues; b) psychologically plausible inductive mechanisms for constraining the search space; c) the nature of linguistic representations, algebraic or statistical. To do so I use three methodologies: experimental procedures, linguistic analyses based on large corpora of naturally occurring speech and text, and computational models implemented in computer simulations. In Chapters 1,2, and 5, I argue that long-distance structural dependencies - traditionally hard to explain with simple distributional analyses based on ngram statistics - can indeed be learned associatively provided the amount of intervening material is highly variable or invariant (the Variability effect). In Chapter 3, I show that simple associative mechanisms instantiated in Simple Recurrent Networks can replicate the experimental findings under the same conditions of variability. Chapter 4 presents successes and limits of such results across perceptual modalities (visual vs. auditory) and perceptual presentation (temporal vs. sequential), as well as the impact of long and short training procedures. In Chapter 5, I show that generalisation to abstract categories from stimuli framed in non-adjacent dependencies is also modulated by the Variability effect. In Chapter 6, I show that the putative separation of algebraic and statistical styles of computation based on successful speech segmentation versus unsuccessful generalisation experiments (as published in a recent Science paper) is premature and is the effect of a preference for phonological properties of the input. In chapter 7 computer simulations of learning irregular constructions suggest that it is possible to learn from positive evidence alone, despite Gold's celebrated arguments on the unlearnability of natural languages. Evolutionary simulations in Chapter 8 show that irregularities in natural languages can emerge from full regularity and remain stable across generations of simulated agents. In Chapter 9 I conclude that the brain may endowed with a powerful statistical device for detecting structure, generalising, segmenting speech, and recovering from overgeneralisations. The experimental and computational evidence gathered here suggests that statistical language learning is more powerful than heretofore acknowledged by the current literature.EThOS - Electronic Theses Online ServiceEuropean Union (EU) (HPRN-CT-1999-00065)GBUnited Kingdo

The ubiquity of frequency effects in first language acquisition

This review article presents evidence for the claim that frequency effects are pervasive in children's first language acquisition, and hence constitute a phenomenon that any successful account must explain. The article is organized around four key domains of research: children's acquisition of single words, inflectional morphology, simple syntactic constructions, and more advanced constructions. In presenting this evidence, we develop five theses. (i) There exist different types of frequency effect, from effects at the level of concrete lexical strings to effects at the level of abstract cues to thematic-role assignment, as well as effects of both token and type, and absolute and relative, frequency. High-frequency forms are (ii) early acquired and (iii) prevent errors in contexts where they are the target, but also (iv) cause errors in contexts in which a competing lower-frequency form is the target. (v) Frequency effects interact with other factors (e.g. serial position, utterance length), and the patterning of these interactions is generally informative with regard to the nature of the learning mechanism. We conclude by arguing that any successful account of language acquisition, from whatever theoretical standpoint, must be frequency sensitive to the extent that it can explain the effects documented in this review, and outline some types of account that do and do not meet this criterion

Spelling English Words: Contributions of Phonological, Morphological and Orthographic Processing Skills of Turkish EFL Students in Grades 6-8

The number of studies examining the simultaneous impact of multi-level metalinguistic skills influencing spelling in English is scarce. Spelling necessitates an integrated and simultaneous working of various linguistic, metalinguistic skills, and socio-cultural (SES) factors. The present study investigates the concurrent influence of multi-level metalinguistic skills including phonological, morphological, and orthographic knowledge in English as well as the impact of socio-cultural factors on EFL spelling of Turkish 6th, 7th, and 8th grade pupils (N= 367). Measures tapping phonological, morphological, and orthographic skills in English (L2) and a background questionnaire were administered to Turkish 6th to 8th grade EFL children recruited in multiple school sites in a city of Turkey. A robust configural baseline confirmatory factor analysis (CFA) model for all grades confirmed that the observed variables constructed a three-factor model (phono, morpho, ortho), as it was hypothesized. The second-order structural equation model (SEM) confirmed the three metalinguistic skills work simultaneously and they tap into the linguistic repertoire construct, which predicted EFL word-spelling of Turkish 6th, 7th, and 8th grade pupils. This provides converging results with linguistic repertoire theory, which suggests utilizing multiple metalinguistic skills when spelling words and teaching spelling. The final SEM model with the integrated SES factors (i.e., SES, home-literacy, and additional English exposure) also reported good model fit statistics where the English exposure factor had the highest regression coefficient on EFL word spelling outcomes. The spelling error analyses showed parallel findings to the quantitative analyses, that phonology and orthography, but not morphology, were the two significant predictors of word spelling errors by Turkish 6th to 8th graders. The key findings can inform foreign language teachers about the roles of phonological, morphological, and orthographic processing skills in English spelling. The pedagogical implications of the present study included the importance of directly teaching the three metalinguistic skills when EFL teachers are engaged in spelling instruction. The findings can also inform Turkey’s foreign language education policy decision making by recommending the tailoring of policy and curriculum according to students’ needs

An enquiry into different forms of special school organization : pedagogic practice and pupil discriminations

SIGLEAvailable from British Library Document Supply Centre-DSC:DX191899 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Language evolution and recursion : an empirical investigation of human hierarchical processing

Tese de doutoramento, Ciências Biomédicas (Neurociências), Universidade de Lisboa, Faculdade de Medicina, 2014Humans generate complex hierarchical structures in a variety of domains such as in language, social organization, music, action sequencing and visual arts. One cognitive capacity associated with this extraordinary generative power is recursion. Recursion is a very efficient method to process hierarchies and it allows the generation of unbounded hierarchical depth from finite means. Recursion can be defined as the ability to represent the embedding of hierarchies within hierarchies of the same kind. Although recursion has been hypothesized as uniquely human and primarily linguistic, the empirical investigation of these hypotheses has been hindered by the absence of methods to test for recursive capabilities outside the domain of language. In this thesis I present a novel task that can be used to investigate the ability to represent recursion (hierarchical self-similarity) in the visuo-spatial domain. I will describe a set of experiments in which I attempt to characterize recursion as a psychological entity by describing its relationship with other cognitive abilities, as well as its developmental patterns and neural underpinnings. The conclusions of this research program are the following: 1) humans can represent recursion in the visuo-spatial domain; 2) this ability requires the acquisition of abstract rules; 3) recursion can be efficiently used to represent information common to different levels of a hierarchy, and it enhances the ability to detect fine-grained hierarchical mistakes, 4) linguistic resources are not specifically active while processing visual recursion neither behaviorally nor at the neural level, however recursion seems to require the integration of spatial and categorical information. The novel task and results presented here open up exciting pathways in the investigation of recursion as a cognitive ability. Because it is a visual task, not requiring verbal instructions or responses, it can also be used to test non-human primates and clinical populations with language impairment.A espécie humana é capaz de produzir hierarquias complexas na linguagem, organização social, música, actividade motora e nas artes visuais. O poder generativo da cognição humana tem sido associado a um módulo computacional designado recursividade, que pode ser definido como a capacidade de representar a incorporação de hierarquias dentro de hierarquias do mesmo tipo. A recursividade pode ser usada de modo eficiente no processamento de hierarquias, permitindo a geração de estruturas infinitamente profundas partindo de um número finito de elementos. Esta capacidade tem sido postulada como exclusivamente humana e primariamente linguística. No entanto, a investigação empírica destas hipóteses tem sido dificultada pela ausência de um método para testar capacidades recursivas fora do domínio linguístico. Nesta tese irei apresentar um novo método para testar a capacidade de representar a recursividade no domínio visuo-espacial. Irei descrever uma série de experiências nas quais caracterizarei a recursividade como uma entidade psicológica, descrevendo de que forma se relaciona com outras capacidades cognitivas, o seu padrão de desenvolvimento e correlatos neurais. As conclusões deste programa de investigação são as seguintes: 1) a espécie humana é capaz de representar recursividade visuo-espacial; 2) esta capacidade requer a aquisição de regras abstractas; 3) a recursividade é usada para representar informação comum a vários níveis hierárquicos e melhora a capacidade de detectar erros estruturais ao nível dos pequenos detalhes; 4) o processamento de recursividade visual não activa especificamente recursos verbais, quer ao nível do comportamento quer ao nível neural, contudo esta capacidade requer a integração de informação espacial e categorial. A tarefa e os resultados inovadores aqui apresentados abrem novas vias de investigação relativamente à capacidade de utilizar recursividade ao nível cognitivo. Por ser uma tarefa visual não requer instruções nem respostas verbais, pelo que pode ser usada para testar primatas não humanos e populações clínicas com defeitos de linguagem.Fundação para a Ciência e a Tecnologia (FCT); European Research Council (ERC