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.

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., & Enfield, N. J. (2006). Projecting the end of a speaker's 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

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.

A B S T R A C TRapid response latencies in conversation suggest that responders start planning before the ongoing turn is finished. Indeed, an earlier EEG study suggests that listeners start planning their responses to questions as soon as they can (Bögels et al., 2015a). The present study aimed to (1) replicate this early planning effect and (2) investigate whether such early response planning incurs a cost on participants' concurrent comprehension of the ongoing turn. During the experiment participants answered questions from a confederate partner. To address aim (1), the questions were designed such that response planning could start either early or late in the turn. Our results largely replicate Bögels et al. (2015a), showing a large positive ERP effect and an oscillatory alpha/beta reduction right after participants could have first started planning their verbal response, again suggesting an early start of response planning. To address aim (2), the confederate's questions also contained either an expected word or an unexpected one to elicit a differential N400 effect, either before or after the start of response planning. We hypothesized an attenuated N400 effect after response planning had started. In contrast, the N400 effects before and after planning did not differ. There was, however, a positive correlation between participants' response time and their N400 effect size after planning had started; quick responders showed a smaller N400 effect, suggesting reduced attention to comprehension and possibly reduced anticipatory processing. We conclude that early response planning can indeed impact comprehension processing.