Effects of pitch accents in attachment ambiguity resolution

Prosodic Disambiguation in First and Second Language Production: English and Korean

This study investigates the use of prosodic cues for syntactic ambiguity resolution by first language (L1) and second language (L2) speakers. In a production experiment, sentences with relative clause attachment ambiguity were elicited in three language conditions: native English speakers' L1 productions as well as Korean-English bilingual speakers' L1 Korean and L2 English productions. The results show that English uses both boundary marking (pause) and relative word prominence (elevated pitch and intensity) for disambiguation, while Korean mainly relies on boundary marking (pre-boundary lengthening and pause). The bilingual speakers have learned to use the English phonological categories such as pitch accents for disambiguation, but their use of phonetic cues to realize these categories still differed from that of native English speakers. In addition, they did not show a significant use of boundary cues. These results are discussed in relation to the typological differences between the prosody of English and of Korean.

Focus Attracts Attachment

There is growing evidence that pitch accents as well as prosodic boundaries can affect syntactic attachment. But is this an effect of their perceptual salience (the Salience Hypothesis), or is it because accents mark the position of focus (the Focus Attraction Hypothesis)? A pair of auditory comprehension experiments shows that focus position, as indicated by preceding wh-questions instead of by pitch accents, affects attachment by drawing the ambiguous phrase to the focus. This supports the Focus Attraction Hypothesis (or a pragmatic version of salience) for both these results and previous results of accents on attachment. These experiments show that information structure, as indicated with prosody or other means, influences sentence interpretation, and suggests a view on which modifiers are drawn to the most important information in a sentence.

Prosodic cue weighting in the processing of ambiguous sentences by native English listeners and Korean listeners of English

Differences in the perception of segmental contrasts by native and non-native listeners have been analyzed as the results of language-specific weightings of acoustic cues in their perception grammar [e.g., Escudero and Boersma, Stud. Second Lang. Acquis. 26, 551-585 (2004)]. However, less attention has been paid to the weighting of prosodic cues. This study investigated the relative importance of four prosodic cues-word duration, pauses, pitch, and intensity-in the resolution of English syntactic ambiguity by native English listeners and Korean learners of English. In a forced-choice processing task, English listeners' disambiguation relied most heavily on pitch, followed by pause and intensity cues, whereas pauses were the only heavily weighted cue for Korean listeners, indicating an influence from their native language. Moreover, Korean listeners' use of prosody for disambiguation was found to be influenced by their age of English acquisition and English proficiency.

Exploring the Similarity Between Implicit and Explicit Prosody: Prosodic Phrasing and Individual Differences

In recent years, work carried out in the context of the implicit prosody hypothesis (IPH) has called into question the assumption that implicit (i.e., silently generated) prosody and explicit (overtly produced) prosody are similar in form. Focusing on prosodic phrasing, the present study explored this issue using an individual differences approach, and using methods that do not rely on the sentence comprehension tests characteristic of work within the IPH program. A large group of native English speakers participated in a production experiment intended to identify individual differences in average prosodic phrase length, phonologically defined. We then explored whether these (explicit) prosodic differences were related to two other kinds of variation, each with a connection to implicit prosody. First, we tested whether individual differences in explicit prosodic phrase length were predicted by individual differences in working memory capacity, a relationship that has been established for implicit prosody. Second, we explored whether participants' explicit prosodic phrase lengths were predictive of their behavior in a silent-reading task in which they had to identify their own implicit prosodic groupings. In both cases, the findings are argued to be consistent with a similarity between explicit and implicit prosody. First, participants with higher working memory capacity (as estimated by reading spans) were associated with longer prosodic phrases. Second, participants who produced longer explicit prosodic phrases in speech tended to report generating longer prosodic phrases in silent reading. Implications for the nature of implicit prosody, and how it can be studied, are discussed.

Pitch accents create dissociable syntactic and semantic expectations during sentence processing

The language system uses syntactic, semantic, as well as prosodic cues to efficiently guide auditory sentence comprehension. Prosodic cues, such as pitch accents, can build expectations about upcoming sentence elements. This study investigates to what extent syntactic and semantic expectations generated by pitch accents can be dissociated and if so, which cues take precedence when contradictory information is present. We used sentences in which one out of two nominal constituents was placed in contrastive focus with a third one. All noun phrases carried overt syntactic information (case-marking of the determiner) and semantic information (typicality of the thematic role of the noun). Two experiments (a sentence comprehension and a sentence completion task) show that focus, marked by pitch accents, established expectations in both syntactic and semantic domains. However, only the syntactic expectations, when violated, were strong enough to interfere with sentence comprehension. Furthermore, when contradictory cues occurred in the same sentence, the local syntactic cue (case-marking) took precedence over the semantic cue (thematic role), and overwrote previous information cued by prosody. The findings indicate that during auditory sentence comprehension the processing system integrates different sources of information for argument role assignment, yet primarily relies on syntactic information.

Sequential Interpretation of Pitch Prominence as Contrastive and Syntactic Information: Contrast Comes First, but Syntax Takes Over

Pitch accent serves multiple duties (encoding lexical accent, syntactic structure, and focus) in spoken Japanese. This study investigates how listeners interpret a role-ambiguous pitch prominence surfacing as F0 rise, which could be a cue to the resolution of a syntactic ambiguity between two possible branching structures, or a signal of contrastive focus on the constituent accompanied by the rise. Two visual world paradigm experiments tested the same Japanese linguistic stimuli with and without pitch emphasis on the second word of structures of the following form: modifier + N1 + N2. In Experiment 1, the visual context suppressed the availability of the contrastive interpretation; in Experiment 2, the visual context made the contrastive interpretation available. We found that the same pitch event can be interpreted as both syntax-encoding and contrast-encoding information within the course of processing the same sentence, as long as contextual information is made visually available. When contrastive focus is pragmatically felicitous, it is computed immediately, as soon as the incoming input is accompanied by a notable pitch prominence (Experiment 2). The same prosodic cue can then be re-interpreted as a signal to syntax after the branching ambiguity is recognized due to subsequent input (Experiments 1 and 2). This is most consistent with the view that an initially assigned prosodic boundary is exploited for re-interpretation.

Accents, Not Just Prosodic Boundaries, Influence Syntactic Attachment

Traditionally, pitch accents are understood to relate to the information structure of a sentence and its discourse connections, while prosodic boundaries indicate groupings of words and affect how constituents attach into a syntactic structure. Here, we show that accents also affect syntactic attachment in multiple different syntactic structures. Three auditory questionnaires on ambiguous attachment sentences (such as Tom reported that Bill was bribed [last May]) find that accenting the higher or lower verb ( reported or bribed) increases the attachment of the final adverbial phrase as a modifier of the accented verb. A fourth experiment shows that accents on verbs or object nouns (in sentences like Jenny sketched a child [with crayons]) also increase the attachment of the final prepositional phrase to the accented head (sketched with crayons versus a child with crayons). Accent effects were small but consistent across sentences with different levels of bias and did not depend on prosodic boundaries. The results suggest that focused elements are important to the main assertion of the sentence and therefore draw the attachment of upcoming material (though the salience of attachment sites may also be important). The results also demonstrate that both prosodic phrasing and pitch accents can affect basic syntactic structure.

Priming Implicit Prosody: Prosodic Boundaries and Individual Differences

Using the structural priming paradigm, the present study explores predictions made by the implicit prosody hypothesis (IPH) by testing whether an implicit prosodic boundary generated from a silently read sentence influences attachment preference for a novel, subsequently read sentence. Results indicate that such priming does occur, as evidenced by an effect on relative clause attachment. In particular, priming an implicit boundary directly before a relative clause--cued by commas in orthography--encouraged high attachment of that relative clause, although the size of the effect depended somewhat on individual differences in pragmatic/communication skills (as measured by the Autism Spectrum Quotient). Thus, in addition to supporting the basic claims of the IPH, the present study demonstrates the relevance of such individual differences to sentence processing, and that implicit prosodic structure, like syntactic structure, can be primed.

Prosody and language comprehension

This review provides a summary of the most recent advances on the study of how prosody is used during language comprehension. Prosody is characterized as an abstract structure composed of discrete tonal elements aligned with the segmental composition of the sentence organized in constituents of increasing size, and this structure is influenced by the phonological, syntactic, and informational structures of the sentence. Here, we discuss evidence that listeners are affected by prosody when establishing those linguistic structures. Prosody has been shown to influence the segmentation of the utterance into syllables and words, and, in some cases, whether a syllable or word is judged to be present or not. The literature on how prosody informs the structural relationship between words and phrases is also discussed, contrasting views that assume a direct (albeit probabilistic) link between syntax and prosody with those that posit a complex interface between syntax and prosodic structure. Finally, the role of prosody in conveying important aspects pertaining to the sentence's information structure (i.e., which parts of the sentence's meaning are highlighted and brought forward to the discourse, which ones are presupposed and left in the background, which attitudes are being conveyed about the concepts or propositional content) has long been recognized. Current research focuses on which prosodic elements contribute to marking the dimensions (or semantic primitives) of the information structure.

The use of prosody during syntactic processing in children and adolescents with autism spectrum disorders

In this study, we employed an eye-gaze paradigm to explore whether children (ages 8–12) and adolescents (ages 12–18) with autism spectrum disorders (ASDs) are able to use prosodic cues to determine the syntactic structure of an utterance. Persons with ASD were compared to typically developing (TD) peers matched on age, IQ, gender, and receptive language abilities. The stimuli were syntactically ambiguous but had a prosodic break that indicated the appropriate interpretation (feel the frog … with the feathervs.feel … the frog with the feather). We found that all groups were equally sensitive to the initial prosodic cues that were presented. Children and teens with ASD used prosody to interpret the ambiguous phrase as rapidly and efficiently as their TD peers. However, when a different cue was presented in subsequent trials, the younger ASD group was more likely to respond in a manner consistent with the initial prosodic cue rather than the new one. Eye-tracking data indicated that both younger groups (ASD and TD) had trouble shifting their interpretation as the prosodic cue changed, but the younger TD group was able to overcome this interference and produce an action consistent with the prosodic cue.

Auditory temporal structure processing in dyslexia: processing of prosodic phrase boundaries is not impaired in children with dyslexia

Reading disability in children with dyslexia has been proposed to reflect impairment in auditory timing perception. We investigated one aspect of timing perception--temporal grouping--as present in prosodic phrase boundaries of natural speech, in age-matched groups of children, ages 6-8 years, with and without dyslexia. Prosodic phrase boundaries are characterized by temporal grouping of functionally related speech elements and can facilitate syntactic processing of speech. For example, temporary syntactic ambiguities, such as early-closure structures, are processed faster when prosodic phrase boundaries are present. We examined children's prosodic facilitation by measuring their efficiency of sentence processing for temporary syntactic ambiguities spoken with (facilitating) versus without (neutral) prosodic phrase boundaries. Both groups of children benefited similarly from prosodic facilitation, displaying faster reaction times in facilitating compared to neutral prosody. These findings indicate that the use of prosodic phrase boundaries for speech processing is not impaired in children with dyslexia.