Prosodic Boundary Effects on Syntactic Disambiguation in Children with Cochlear Implants, and in Normal Hearing Adults and Children

Theoretical Framework: Manipulations of prosodic structure influence how listeners interpret syntactically ambiguous sentences. However, the interface between prosody and syntax has received very little attention in languages other than English. Furthermore, many children with cochlear implants (CI) have deficits in sentence comprehension. Until now, these deficits have been attributed only to syntax, leaving prosody a neglected area, despite its clear deficit on this population and the role it plays in sentence comprehension. Purposes: Experiment 1 investigates prosodic boundary effects on the comprehension of attachment ambiguities in Brazilian Portuguese while experiment 2 investigates these effects in Brazilian Portuguese speaking children with CIs. Both experiments tested two hypotheses relying on the notion of boundary strength: the absolute boundary hypothesis (ABH) and the relative boundary hypothesis (RBH). The ABH states that only the high boundary before the ambiguous constituent influences attachment whereas the RBH advocates that the high boundary before the ambiguous constituent can only be interpreted according to the relative size of an earlier low boundary. Specific predictions of the two hypotheses were tested. Relationships between attachment results and performance on psychoacoustic tests of gap detection threshold and frequency limen were also investigated. Materials: The experiments were designed on E-Prime 2.0 software (Psychology Software Tools, Pittsburgh, PA). The sentences were recorded on Praat software (Boersma & Weenink, 2013), controlling for F0, duration of components and pauses between components. The prosodic boundaries were measured with the ToBI coding system distinguishing acoustic measures of intermediate phrase (ip) and intonational phrase (IPh) boundaries. Methods: Twenty-three normal hearing (NH) adults, 15 NH children and 13 children with CIs who are monolingual speakers of Brazilian Portuguese participated in a computerized sentence comprehension task. The target stimuli consisted of eight base sentences containing a prepositional phrase attachment ambiguity. Prosodic boundaries were manipulated by varying IPh, ip and null boundaries. Participants also engaged on psychoacoustic tests that investigated gap detection threshold and frequency discrimination ability on nonlinguistic stimuli. An adaptive 3-interval forced-choice procedure was used in gap detection. For the frequency discrimination task, participants completed a same-different two-alternative forced choice task. Results and Discussion: Unlike NH adults and children, children with CIs did not exhibit an overall effect of prosody on syntactic disambiguation. Nonetheless, adults and children with NH and children CIs had the same two predictions of the RBH confirmed, suggesting that they perceived and used the relative size of the boundaries similarly. Two predictions of the ABH were confirmed for adults with NH whereas only one was confirmed for children with NH. The ABH does not govern the syntactic disambiguation of children with CIs. Children with NH were significantly slower than adults with NH to indicate a high attachment response in all prosodic types. However, hearing status did not influence processing speed. Gap detection thresholds and frequency limens on nonlinguistic stimuli did not influence the attachment of syntactically ambiguous sentences with different prosodic boundaries in adults and children with NH. Although children with CIs exhibited a decreased ability to perceive the acoustic changes on a nonlinguistic level, no correlation was found between frequency limens and proportion of high attachment. In children with CIs, gap detection thresholds were only correlated with the proportion of high attachment on sentences with strong prosody contrasts, suggesting that gap detection thresholds possibly influenced the attachment of syntactically ambiguous sentences with strong prosodic dissimilarity between boundaries

The failure to use gender information in parsing: A comment on van Berkum, Brown, and Hagoort (1999)

We critically review the empirical evidence published by van Berkum, Brown and Hagoort (1999a, 1999b) against syntax-first models of sentence parsing. According to van Berkum et al., discourse factors and word gender information are used instantaneously to guide the parser. First, we note that the density of the experimental trials (relative to fillers) and the slow presentation rate of the van Berkum et al. design seem likely to have elicited the use of tactics involving rapid re-analysis of the material. Second, we present new data from a questionnaire study showing that the grammatical gender information of a relative pronoun in Dutch is often completely ignored, even during the wrap-up at the end of the sentence

Speaker emotion can affect ambiguity production

Does speaker emotion affect degree of ambiguity in referring expressions? We used referential communication tasks preceded by mood induction to examine whether positive emotional valence may be linked to ambiguity of referring expressions. In Experiment 1, participants had to identify sequences of objects with homophonic labels (e.g., the animal bat, a baseball bat) for hypothetical addressees. This required modification of the homophones. Happy speakers were less likely to modify the second homophone to repair a temporary ambiguity (i.e., they were less likely to say … first cover the bat, then cover the baseball bat …). In Experiment 2, participants had to identify one of two identical objects in an object array, which required a modifying relative clause (the shark that's underneath the shoe). Happy speakers omitted the modifying relative clause twice as often as neutral speakers (e.g., by saying Put the shark underneath the sheep), thereby rendering the entire utterance ambiguous in the context of two sharks. The findings suggest that one consequence of positive mood appears to be more ambiguity in speech. This effect is hypothesised to be due to a less effortful processing style favouring an egocentric bias impacting perspective taking or monitoring of alignment of utterances with an addressee's perspective

Prosody of classic garden path sentences : The horse raced faster when embedded

Prosody, it is assumed, does not always disambiguate syntax. We investigate one classic case at point from the psycholinguistics literature: garden path sentences involving the main-verb vs. reduced relative clause contrast (the horse raced past the barn (and) fell). Despite their centrality in shaping theoies of sentence processing, no experimental work to date has investigated the prosody of these sentences. We show that, contrary to previous assumptions (Fodor 2002, Wagner & Watson 2010), this contrast is prosodically disambiguated, but that this disambiguation can only be observed when the relevant clauses are embedded within a matrix clause which provides a baseline pace. Prosodic disambiguation obtains through pace modulation, with faster pace associated with the embedded/reduced relative reading and regular pace (no change) with the main-verb analysis. The essential contribution of the matrix sentence is to provide a baseline pace without which it is impossible to establish whether a change took place. Importantly, duration is solely determined by prosody and independent from complexity: faster pace is associated with the more complex structure

Age-Related Changes to the Production of Linguistic Prosody

The production of speech prosody (the rhythm, pausing, and intonation associated with natural speech) is critical to effective communication. The current study investigated the impact of age-related changes to physiology and cognition in relation to the production of two types of linguistic prosody: lexical stress and the disambiguation of syntactically ambiguous utterances. Analyses of the acoustic correlates of stress: speech intensity (or sound-pressure level; SPL), fundamental frequency (F0), key word/phrase duration, and pause duration revealed that both young and older adults effectively use these acoustic features to signal linguistic prosody, although the relative weighting of cues differed by group. Differences in F0 were attributed to age-related physiological changes in the laryngeal subsystem, while group differences in duration measures were attributed to relative task complexity and the cognitive-linguistic load of these respective tasks. The current study provides normative acoustic data for older adults which informs interpretation of clinical findings as well as research pertaining to dysprosody as the result of disease processes

Perception of phrasal prosody in the acquisition of European Portuguese

A central issue in language acquisition is the segmentation of speech into linguistic units and structures. This thesis examines the role played by phrasal prosody in speech segmentation in the acquisition of European Portuguese, both in the processing of globally ambiguous sentences by 4 and 5 year old children and in early word segmentation by 12 month-old infants. Past studies have shown that phrasal prosody is used by adults in ambiguity resolution, for example to disambiguate syntactically ambiguous sentences involving a low or high attachment interpretation of a given phrase (e.g, Hide the rabbit with a cloth). In a first exploratory experiment, and given previous unclear findings in the literature on European Portuguese, we investigated whether prosodic phrasing might guide speech chunking and interpretation of these globally ambiguous sentences by adult listeners. In an eye-tracking experiment, which also included a pointing task, we found that EP adult speakers were not able to use phrasal prosody to disambiguate the structures tested. Both the results from eye gaze and the pointing task indicated the presence of a high attachment preference in the language, regardless of phrasal prosody. These findings required a better understanding of adult interpretation of these utterances before a productive study could be conducted with young children. Building on the lessons learned from this exploratory study, we conducted two new experiments examining young children (and adults) abilities to use prosody, in a different sort of globally ambiguous utterances where differences in phrasal prosody were triggered by the syntaxprosody interface and part of the common, default prosody of the sentences (i.e., in compound word versus list reading structures, like ‘guarda-chuva e pato,’ umbrella and duck vs. ‘guarda, chuva e pato’, guard, rain and duck). An eye-tracking paradigm (along the lines of De Carvalho, Dautriche, & Christophe, 2016a) was used to monitor the use of phrasal prosody, namely the contrast between a Prosodic Word boundary (PW) in the compound word interpretation and an Intonational Phrase boundary (IP) in the list interpretation, during auditory sentence processing. An offline pointing task was also included. Results have shown a clear developmental trend in the use of phrasal prosody to guide sentence interpretation, from a general inability at age 4 to a still developing ability at age 5, when local prosodic cues were still not enough and the support of distal cues was necessary to achieve disambiguation, unlike for adults. While the previous experiments investigated the ability to use prosody to constrain lexical and syntactic analysis, thus looking into the combination of lexical, syntactic and prosodic knowledge at a young age, in a final set of experiments, we asked whether phrasal prosody is exploited to chunk the speech signal into words by infants, in the absence of prior lexical knowledge. Using a modified version of the visual habituation paradigm (Altvater-Mackensen & Mani, 2013), we tested 12-month-olds use of phrasal prosody in early word segmentation beyond the utterance edge factor, by examining the effects of two prosodic boundaries in utterance internal position, namely the IP boundary (in the absence of pause) and the PW boundary. Our findings showed that early segmentation abilities are constrained by phrasal prosody, since they crucially depended on the location of the target word in the prosodic structure of the utterance. Implications of the findings in this thesis were discussed in the context of prosodic differences across languages, taking advantage of the atypical combination of prosodic properties that characterizes EP.No âmbito da aquisição da linguagem, a segmentação de fala em unidades e estruturas linguísticas é uma questão central. Esta dissertação examina o papel desempenhado pelo fraseamento prosódico na segmentação de fala, na aquisição do Português Europeu (PE), no que diz respeito ao processamento de frases globalmente ambíguas por parte de crianças aos 4 e 5 anos de idade e à segmentação precoce de palavras aos 12 meses. Estudos anteriores mostraram que o fraseamento prosódico é usado pelos adultos na resolução de ambiguidade, por exemplo, para desambiguar frases sintaticamente ambíguas envolvendo uma interpretação de low ou high attachment de um dado sintagma (e.g.,’Hide the rabbit with a cloth’ Esconde o coelho com um pano). Num estudo exploratório, e dados os resultados pouco claros de trabalhos anteriores para o Português Europeu, investigámos se o fraseamento prosódico poderia guiar a organização da fala em unidades específicas, bem como a interpretação das frases globalmente ambíguas, por parte de participantes adultos. Numa experiência de eye-tracking, que incluía também uma tarefa de apontar, observámos que os participantes adultos do PE não conseguiram usar o fraseamento prosódico para desambiguar as estruturas testadas. Quer os resultados do movimento dos olhos quer os da tarefa de apontar evidenciaram a preferência pelo high attachment na língua, independentemente do fraseamento prosódico envolvido. Estes resultados implicaram compreender melhor a interpretação adulta destes enunciados antes de se conduzir um estudo com crianças. Com base nas observações feitas neste estudo exploratório, conduzimos duas experiências novas por forma a examinar a capacidade de uso da prosódia, por parte das crianças (e adultos), num outro conjunto de enunciados globalmente ambíguos, em que as diferenças de fraseamento prosódico foram desencadeadas pela interface sintaxe-prosódia e por parte da prosódia default das frases (i.e., em compostos versus estruturas em formato de lista, como ‘guarda-chuva e pato,’ vs. ‘guarda, chuva e pato’). Um paradigma de eye-tracking (na linha de De Carvalho, Dautriche, & Christophe, 2016a) foi usado para monitorizar o uso do fraseamento prosódico, nomeadamente o contraste entre uma fronteira de Palavra Prosódica (PW) na interpretação de composto e uma fronteira de Sintagma Entoacional (IP) na interpretação de lista, durante o processamento auditivo da frase. Também foi incluída uma tarefa off-line de apontar. Os resultados mostraram um claro desenvolvimento no uso do fraseamento prosódico na interpretação das frases; de uma incapacidade geral de interpretação das frases aos 4 anos a uma clara evolução nas competências aos 5 anos, altura em que as pistas prosódicas locais ainda são insuficientes e o apoio do contexto prosódico da frase é necessário para alcançar a desambiguação, diferentemente do adulto. Enquanto as experiências anteriores investigaram a capacidade de usar a prosódia para restringir a análise lexical e sintática, olhando para a combinação de conhecimento lexical, sintático e prosódico numa idade precoce, num conjunto final de experiências, questionámos se o fraseamento prosódico é explorado, por parte das crianças, para organizar o sinal de fala em palavras, na ausência de conhecimento lexical prévio. Recorrendo a uma versão modificada do paradigma visual habituation (Altvater-Mackensen & Mani, 2013), testámos o uso do fraseamento prosódico para a segmentação precoce de palavras além do fator limite do enunciado, por parte de crianças com 12 meses de idade. Examinámos o efeito de duas fronteiras prosódicas em posição interna de enunciado, nomeadamente a fronteira de IP (na ausência de pausa) e a fronteira de PW. Os nossos resultados mostraram que a capacidade de segmentação precoce é afetada pelo fraseamento prosódico, na medida em que depende da localização da palavra-alvo na estrutura prosódica do enunciado. Partindo da combinação atípica das propriedades prosódicas que caracterizam o PE, as implicações do conjunto de estudos desenvolvidos no âmbito desta dissertação foram discutidas no contexto das diferenças prosódicas entre línguas