Sara Bögels

The interplay between prosody and syntax in sentence processing: The case of subject-and object-control verbs

This study addresses the question whether prosodic information can affect the choice for a syntactic analysis in auditory sentence processing. We manipulated the prosody (in the form of a prosodic break; PB) of locally ambiguous Dutch sentences to favor one of two interpretations. The experimental items contained two different types of so-called control verbs (subject and object control) in the matrix clause and were syntactically disambiguated by a transitive or by an intransitive verb. In Experiment 1, we established the default off-line preference of the items for a transitive or an intransitive disambiguating verb with a visual and an auditory fragment completion test. The results suggested that subject- and object-control verbs differently affect the syntactic structure that listeners expect. In Experiment 2, we investigated these two types of verbs separately in an on-line ERP study. Consistent with the literature, the PB elicited a closure positive shift. Furthermore, in subject-control items, an N400 effect for intransitive relative to transitive disambiguating verbs was found, both for sentences with and for sentences without a PB. This result suggests that the default preference for subject-control verbs goes in the same direction as the effect of the PB. In object-control items, an N400 effect for intransitive relative to transitive disambiguating verbs was found for sentences with a PB but no effect in the absence of a PB. This indicates that a PB can affect the syntactic analysis that listeners pursue.

Neural signatures of response planning occur midway through an incoming question in conversation

A striking puzzle about language use in everyday conversation is that turn-taking latencies are usually very short, whereas planning language production takes much longer. This implies overlap between language comprehension and production processes, but the nature and extent of such overlap has never been studied directly. Combining an interactive quiz paradigm with EEG measurements in an innovative way, we show that production planning processes start as soon as possible, that is, within half a second after the answer to a question can be retrieved (up to several seconds before the end of the question). Localization of ERP data shows early activation even of brain areas related to late stages of production planning (e.g., syllabification). Finally, oscillation results suggest an attention switch from comprehension to production around the same time frame. This perspective from interactive language use throws new light on the performance characteristics that language competence involves.

Listeners use intonational phrase boundaries to project turn ends in spoken interaction

In conversation, turn transitions between speakers often occur smoothly, usually within a time window of a few hundred milliseconds. It has been argued, on the basis of a button-press experiment [De Ruiter, J. P., Mitterer, H., &E nfield, N. J. (2006). Projecting the end of a speakers turn: A cognitive cornerstone of conversation. Language, 82(3):515–535], that participants in conversation rely mainly on lexico-syntactic information when timing and producing their turns, and that they do not need to make use of intonational cues to achieve smooth transitions and avoid overlaps. In contrast to this view, but in line with previous observational studies, our results from a dialogue task and a button-press task involving questions and answers indicate that the identification of the end of intonational phrases is necessary for smooth turn-taking. In both tasks, participants never responded to questions (i.e., gave an answer or pressed a button to indicate a turn end) at turn-internal points of syntactic completion in the absence of an intonational phrase boundary. Moreover, in the button-press task, they often pressed the button at the same point of syntactic completion when the final word of an intonational phrase was cross-spliced at that location. Furthermore, truncated stimuli ending in a syntactic completion point but lacking an intonational phrase boundary led to significantly delayed button presses. In light of these results, we argue that earlier claims that intonation is not necessary for correct turn-end projection are misguided, and that research on turn-taking should continue to consider intonation as a source of turn-end cues along with other linguistic and communicative phenomena.

Breathing for answering: the time course of response planning in conversation

We investigate the timing of pre-answer inbreaths in order to shed light on the time course of response planning and execution in conversational turn-taking. Using acoustic and inductive plethysmography recordings of seven dyadic conversations in Dutch, we show that pre-answer inbreaths in conversation typically begin briefly after the end of questions. We also show that the presence of a pre-answer inbreath usually co-occurs with substantially delayed answers, with a modal latency of 576 vs. 100 ms for answers not preceded by an inbreath. Based on previously reported minimal latencies for internal intercostal activation and the production of speech sounds, we propose that vocal responses, either in the form of a pre-utterance inbreath or of speech proper when an inbreath is not produced, are typically launched in reaction to information present in the last portion of the interlocutors turn. We also show that short responses are usually made on residual breath, while longer responses are more often preceded by an inbreath. This relation of inbreaths to answer length suggests that by the time an inbreath is launched, typically during the last few hundred milliseconds of the question, the length of the answer is often prepared to some extent. Together, our findings are consistent with a two-stage model of response planning in conversational turn-taking: early planning of content often carried out in overlap with the incoming turn, and late launching of articulation based on the identification of turn-final cues.

Prosodic breaks in sentence processing investigated by event-related potentials

Prosodic breaks (PBs) can indicate a sentence’s syntactic structure. Event-related brain potentials (ERPs) are an excellent way to study auditory sentence processing, since they provide an on-line measure across a complete sentence, in contrast to other on- and off-line methods. ERPs for the first time allowed investigating the processing of a PB itself. PBs reliably elicit a closure positive shift (CPS). We first review several studies on the CPS, leading to the conclusion that it is elicited by abstract structuring or phrasing of the input. Then we review ERP findings concerning the role of PBs in sentence processing as indicated by ERP components like the N400, P600 and LAN. We focus on whether and how PBs can (help to) disambiguate locally ambiguous sentences. Differences in results between different studies can be related to differences in items, initial parsing preferences and tasks. Finally, directions for future research are discussed.

The Brain Behind the Response: Insights Into Turn-taking in Conversation From Neuroimaging

ABSTRACT This article reviews the prospects for the cross-fertilization of conversation analytic (CA) and neurocognitive studies of conversation, focusing on turn taking. Although conversation is the primary ecological niche for language use, relatively little brain research has focused on interactive language use, partly due to the challenges of using brain-imaging methods that are controlled enough to perform sound experiments but still reflect the rich and spontaneous nature of conversation. Recently, though, brain researchers have started to investigate conversational phenomena—for example, by using “overhearer” or controlled interaction paradigms. We review neuroimaging studies related to turn-taking and sequence organization, phenomena historically described by CA. These studies, for example, show early action recognition and immediate planning of responses midway during an incoming turn. The review discusses studies with an eye to a fruitful interchange between CA and neuroimaging research on conversation and an indication of how these disciplines can benefit from each other.

The role of prosodic breaks and pitch accents in grouping words during on-line sentence processing

The present study addresses the question whether accentuation and prosodic phrasing can have a similar function, namely, to group words in a sentence together. Participants listened to locally ambiguous sentences containing object- and subject-control verbs while ERPs were measured. In Experiment 1, these sentences contained a prosodic break, which can create a certain syntactic grouping of words, or no prosodic break. At the disambiguation, an N400 effect occurred when the disambiguation was in conflict with the syntactic grouping created by the break. We found a similar N400 effect without the break, indicating that the break did not strengthen an already existing preference. This pattern held for both object- and subject-control items. In Experiment 2, the same sentences contained a break and a pitch accent on the noun following the break. We argue that the pitch accent indicates a broad focus covering two words [see Gussenhoven, C. On the limits of focus projection in English. In P. Bosch & R. van der Sandt (Eds.), Focus: Linguistic, cognitive, and computational perspectives. Cambridge: University Press, 1999], thus grouping these words together. For object-control items, this was semantically possible, which led to a “good-enough” interpretation of the sentence. Therefore, both sentences were interpreted equally well and the N400 effect found in Experiment 1 was absent. In contrast, for subject-control items, a corresponding grouping of the words was impossible, both semantically and syntactically, leading to processing difficulty in the form of an N400 effect and a late positivity. In conclusion, accentuation can group words together on the level of information structure, leading to either a semantically “good-enough” interpretation or a processing problem when such a semantic interpretation is not possible.

Processing consequences of superfluous and missing prosodic breaks in auditory sentence comprehension.

This ERP study investigates whether a superfluous prosodic break (i.e., a prosodic break that does not coincide with a syntactic break) has more severe processing consequences during auditory sentence comprehension than a missing prosodic break (i.e., the absence of a prosodic break at the position of a syntactic break). Participants listened to temporarily ambiguous sentences involving a prosody-syntax match or mismatch. The disambiguation of these sentences was always lexical in nature in the present experiment. This contrasts with a related study by Pauker, Itzhak, Baum, and Steinhauer (2011), where the disambiguation was of a lexical type for missing PBs and of a prosodic type for superfluous PBs. Our results converge with those of Pauker et al. (2011): superfluous prosodic breaks lead to more severe processing problems than missing prosodic breaks. Importantly, the present results extend those of Pauker et al. (2011) showing that this holds when the disambiguation is always lexical in nature. Furthermore, our results show that the way listeners use prosody can change over the course of the experiment which bears consequences for future studies.

Oscillatory Brain Responses Reflect Anticipation during Comprehension of Speech Acts in Spoken Dialog

Everyday conversation requires listeners to quickly recognize verbal actions, so-called speech acts, from the underspecified linguistic code and prepare a relevant response within the tight time constraints of turn-taking. The goal of this study was to determine the time-course of speech act recognition by investigating oscillatory EEG activity during comprehension of spoken dialog. Participants listened to short, spoken dialogs with target utterances that delivered three distinct speech acts (Answers, Declinations, Pre-offers). The targets were identical across conditions at lexico-syntactic and phonetic/prosodic levels but differed in the pragmatic interpretation of the speech act performed. Speech act comprehension was associated with reduced power in the alpha/beta bands just prior to Declination speech acts, relative to Answers and Pre-offers. In addition, we observed reduced power in the theta band during the beginning of Declinations, relative to Answers. Based on the role of alpha and beta desynchronization in anticipatory processes, the results are taken to indicate that anticipation plays a role in speech act recognition. Anticipation of speech acts could be critical for efficient turn-taking, allowing interactants to quickly recognize speech acts and respond within the tight time frame characteristic of conversation. The results show that anticipatory processes can be triggered by the characteristics of the interaction, including the speech act type.

Dual-tasking with simple linguistic tasks: Evidence for serial processing

In contrast to the large amount of dual-task research investigating the coordination of a linguistic and a non-linguistic task, little research has investigated how two linguistic tasks are coordinated. However, such research would greatly contribute to our understanding of how interlocutors combine speech planning and listening in conversation. In three dual-task experiments we studied how participants coordinated the processing of an auditory stimulus (S1), which was either a syllable or a tone, with selecting a name for a picture (S2). Two SOAs, of 0 ms and 1000 ms, were used. To vary the time required for lexical selection and to determine when lexical selection took place, the pictures were presented with categorically related or unrelated distractor words. In Experiment 1 participants responded overtly to both stimuli. In Experiments 2 and 3, S1 was not responded to overtly, but determined how to respond to S2, by naming the picture or reading the distractor aloud. Experiment 1 yielded additive effects of SOA and distractor type on the picture naming latencies. The presence of semantic interference at both SOAs indicated that lexical selection occurred after response selection for S1. With respect to the coordination of S1 and S2 processing, Experiments 2 and 3 yielded inconclusive results. In all experiments, syllables interfered more with picture naming than tones. This is likely because the syllables activated phonological representations also implicated in picture naming. The theoretical and methodological implications of the findings are discussed.