We examine the influence of inferring interlocutors' referential intentions from their body movements at the early stage of lexical acquisition. By testing human subjects and comparing their performances in different learning conditions, we find that those embodied intentions facilitate both word discovery and word-meaning association.

Two gating studies, a forced-choice identification study and 2 series of cross-modal repetition priming experiments, traced the time course of recognition of words with onset embeddings (captain) and short words in contexts that match (cap tucked) or mismatch (cap looking) with longer words. Results suggest that acoustic differences in embedded syllables assist the perceptual system in discriminating short words from the start of longer words. The ambiguity created by embedded words is therefore not as severe as predicted by models of spoken word recognition based on phonemic representations. These additional acoustic cues combine with post-offset information in identifying onset-embedded words in connected speech. An important problem in the perception of connected speech is segmentation: how listeners divide the speech stream into individual lexical units or words. Words in fluent speech are not separated by silence in the same way that printed words are divided by blank spaces, yet connected speech is perceived as a sequence of individual words. This perceptual experience clearly reflects acquired language-specific knowledge, because listeners do not have the

INTRODUCTION Current models of speech perception are divided with regard to the status of "phonology", or general implicit knowledge of the sound patterns of a language. In the TRACE model (McClelland & Elman, 1986) the phonotactic and prosodic constraints of phonology are treated as epiphenomenal from regularities in the lexicon. In contrast, Norris (1994), Vitevich and Luce (1998) and MERGE (Norris, McQueen, & Cutler, 2000) respond to a growing body of experimental literature indicating that low-level encoding of the speech signal (the level whose result is passed up to the lexicon for potential word matches) is sensitive to phonotactic and prosodic constraints. Here, I will explore the consequences of the assumption that the architecture of the speech perception system includes a fast phonological preprocessor (hereafter, an FPP) which uses language-specific, but still general, prosodic and phonotactic patterns to chunk the speech stream on its way up to the lexical network

The current emphasis in second language teaching lies in the achievement of communicative effectiveness. In line with this approach, pronunciation training is nowadays geared towards helping learners avoid serious pronunciation errors, rather than eradicating the finest traces of foreign accent. However, to devise optimal pronunciation training programmes, systematic information on these pronunciation problems is needed, especially in the case of the development of Computer Assisted Pronunciation Training systems. The research reported on in this paper is aimed at obtaining systematic information on segmental pronunciation errors made by learners of Dutch with different mother tongues. In particular, we aimed at identifying errors that are frequent, perceptually salient, persistent, and potentially hampering to communication. To achieve this goal we conducted analyses on different corpora of speech produced by L2 learners under different conditions. This resulted in a robust inventory of pronunciation errors that can be used for designing efficient pronunciation training programs.

INTRODUCTION Results of experiments on lexical access during speech perception support cognitive models in which the mental lexicon is characterized as a network. Words are incrementally activated as the speech signal is perceived over time. A word is recognized when its overall activation level passes threshhold, with the time point at which this event occurs depending on the baseline activation, the degree of similarity between the speech signal and the lexical representation, and the extent of competition from other similar-sounding words. Models of this general class are divided with regard to the status of "phonology", or general implicit knowledge of the sound patterns of a language. The pioneering TRACE model (McClelland and Elman, 1986) includes a level of featural and segmental encoding, but the phonotactic and prosodic constraints of phonology are treated as epiphenomenal from regularities in the lexicon. Thus, the model has no level of representation which encodes

This thesis examines an important issue in spoken word recognition; how the perceptual system segments connected speech into lexical units or words. Research on this topic has investigated the role of different sources of information in dividing up the speech stream: acoustic cues in the speech signal, statistical regularities in the structure of the language or through the identification of individual lexical items. This research focuses on cases in which the location of word boundaries may be ambiguous by one or more of these segmentation mechanisms using words embedded at the onset of longer words (such as cap in captain). The ambiguities proposed for onset-embedded words have motivated accounts of segmentation based on competition between alternative parses of speech into words. In these accounts, the recognition of embedded words is delayed until after their offset when subsequent input rules out longer competitors. In this thesis it is demonstrated that training a simple recurrent network to activate a representation of all the words in a sequence allows a connectionist network to learn the appropriate delay to allow the identification of onset-embedded words without requiring directly implemented competition between words. Both lexical competition and recurrent network models assume ambiguity between onset-embedded words and equivalent syllables in longer competitors. Acoustic analysis carried out in this thesis confirms the presence of reliable acoustic differences between syllables in short and long words. A series of experiments using gating and cross-modal priming suggest that the perceptual system uses these acoustic differences to discriminate embedded words from the onset of longer competitors and that match or mismatch with longer competitors may be less important for the identification of onset-embedded words. These results are interpreted within a revised version of the recurrent network model, incorporating input representing the acoustic differences between syllables in short and long words.

While many computational models have been created to explore how children might learn to segment words, the focus has largely been on achieving higher levels of performance and exploring cues suggested by artificial learning experiments. We propose a broader focus that includes designing models that display properties of infants ’ performance as they begin to segment words. We develop an efficient bootstrapping online learner with this focus in mind, and evaluate it on child-directed speech. In addition to attaining a high level of performance, this model predicts the error patterns seen in infants learning to segment words. 1

Abstract: In a series of studies, we examined how mothers naturally stress words across multiple mentions in speech to their infants and how this marking influences infants ' recognition of words in fluent speech. We first collected samples of mothers ' infant-directed speech using a technique that induced multiple repetitions of target words. Acoustic analyses revealed that mothers systematically alternated between emphatic and nonemphatic stress when talking to their infants. Using the headturn preference procedure, we then tested 7.5-month-old infants on their ability to detect familiarized bisyllabic words in fluent speech. Stress of target words (emphatic and nonemphatic) was systematically varied across familiarization and recognition phases of four experiments. Results indicated that, although infants generally prefer listening to words produced with emphatic stress, recognition was enhanced when the degree of emphatic stress at familiarization matched the degree of emphatic stress at recognition.

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Previous investigations have claimed that speech perception uses languagespecific strategies and that, in particular, English does not use a strategy based on syllables (Cutler, Mehler, Norris, and Segui, 1983; 1986). This conclusion is based on a failure to replicate the interaction between target type and word type in fragment monitoring experiments that was originaly found in French (Mehler et al., 1981) with English subjects and materials. Here, we explore the possibility that this might be due to one of three related hypotheses: i) syllable boundaries in English depend on the stress value of the following syllable; ii) English listeners use the foot instead of the syllable in speech perception; iii) English subjects posit a perceptual boundary before an unreduced (or "strong") syllable but not before a reduced, or "weak" one. These three hypotheses can all be tested on the basis of the same contrasts and so we group them together under the rubric of "stress-sensitive strategies" (...