Statistical and explicit learning of graphotactic patterns with no phonological counterpart: Evidence from artificial lexicon studies with 6– to 7-year-olds and adults

Children are powerful statistical spellers: They can learn novel written patterns with phonological counterparts under experimental conditions, via implicit learning processes, akin to “statistical learning” processes established for spoken language acquisition. Can these mechanisms fully account for children’s knowledge of written patterns? How does this ability relate to literacy measures? How does it compare to explicit learning? This thesis addresses these questions in a series of artificial lexicon experiments, inducing graphotactic learning under incidental and explicit conditions, and comparing it with measures of literacy. The first experiment adapted an existing design (Samara & Caravolas, 2014), with the goal of searching for stronger effects. Subsequent experiments address a further limitation: Previous studies assessed learning of spelling rules which have counterparts in spoken language; however, while this is also the case for some naturalistic spelling rules (e.g., English phonotactics prohibit word initial /ŋ/ and accordingly, written words cannot begin with ng), there are also purely visual constraints (graphotactics) (e.g., gz is an illegal spelling of a frequent word-final sound combination in English: *bagz). Can children learn patterns unconfounded from correlated phonotactics? In further experiments, developing and skilled spellers were exposed to patterns replete of phonotactic cues. In post-tests, participants generalized over both positional constraints embedded in semiartificial strings, and contextual constraints created using homophonic non-word stimuli. This was demonstrated following passive exposure and even under meaningful (word learning) conditions, and success in learning graphotactics was not hindered by learning word meanings. However, the effect sizes across this thesis remained small, and the hypothesized positive associations between learning performance under incidental conditions and literacy measures were never observed. This relationship was only found under explicit conditions, when pattern generalization benefited. Investigation of age effects revealed that adults and children show similar patterns of learning but adults learn faster from matched text

Towards an automatic speech recognition system for use by deaf students in lectures

According to the Royal National Institute for Deaf people there are nearly 7.5 million hearing-impaired people in Great Britain. Human-operated machine transcription systems, such as Palantype, achieve low word error rates in real-time. The disadvantage is that they are very expensive to use because of the difficulty in training operators, making them impractical for everyday use in higher education. Existing automatic speech recognition systems also achieve low word error rates, the disadvantages being that they work for read speech in a restricted domain. Moving a system to a new domain requires a large amount of relevant data, for training acoustic and language models. The adopted solution makes use of an existing continuous speech phoneme recognition system as a front-end to a word recognition sub-system. The subsystem generates a lattice of word hypotheses using dynamic programming with robust parameter estimation obtained using evolutionary programming. Sentence hypotheses are obtained by parsing the word lattice using a beam search and contributing knowledge consisting of anti-grammar rules, that check the syntactic incorrectness’ of word sequences, and word frequency information. On an unseen spontaneous lecture taken from the Lund Corpus and using a dictionary containing "2637 words, the system achieved 815% words correct with 15% simulated phoneme error, and 73.1% words correct with 25% simulated phoneme error. The system was also evaluated on 113 Wall Street Journal sentences. The achievements of the work are a domain independent method, using the anti- grammar, to reduce the word lattice search space whilst allowing normal spontaneous English to be spoken; a system designed to allow integration with new sources of knowledge, such as semantics or prosody, providing a test-bench for determining the impact of different knowledge upon word lattice parsing without the need for the underlying speech recognition hardware; the robustness of the word lattice generation using parameters that withstand changes in vocabulary and domain

Catching words in a stream of speach:computational simulations of segmenting transcribed child-directed speech

De segmentatie van continue spraak in lexicale eenheden is één van de eerste vaardigheden die een kind moet leren gedurende de taalverwerving. Dit proefschrift onderzoekt segmentatie met behulp van computationeel modelleren en computationele simulaties. Segmentatie is moeilijker dan het op het eerste gezicht kan lijken. Kinderen moeten woorden vinden in een continue stroom van spraak, zonder kennis van woorden te hebben. Gelukkig laten experimentele studies zien dat kinderen en volwassen een aantal aanwijzingen uit de invoer gebruiken, alsmede simpele strategieën die gebruik maken van deze aanwijzingen, om spraak te segmenteren. Nog interessanter is dat een aantal van deze aanwijzingen taal-onafhankelijk zijn, waardoor een taalverwerver continue input kan segmenteren voordat het een enkel woord kent. De modellen die in dit proefschrift voorgesteld worden, verschillen op twee belangrijke vlakken van modellen uit de literatuur. Ten eerste gebruiken ze lokale strategieën – in tegenstelling tot globale optimalisatie – die gebruik maken van aanwijzingen waarvan bekend is dat kinderen ze gebruiken, namelijk voorspelbaarheidsstatistieken, fonotactiek en lexicale beklemtoning. Ten tweede worden deze aanwijzingen gecombineerd met behulp van een expliciet aanwijzing-combinatie model, dat eenvoudig uitgebreid kan worden met meer aanwijzingen

Interlitteraria : Tartu Ülikooli maailmakirjanduse õppetooli ja Eesti Võrdleva Kirjandusteaduse Assotsiatsiooni rahvusvaheline ajakiri = international refereed edition of the Chair of Comparative Literature of Tartu University and the Estonian Association of Comparative Literature

http://www.ester.ee/record=b1226153*es