Turn-end Estimation in Conversational Turn-taking: The Roles of Context and Prosody

Visual bodily signals and conversational context benefit the anticipation of turn ends

The typical pattern of alternating turns in conversation seems trivial at first sight. But a closer look quickly reveals the cognitive challenges involved, with much of it resulting from the fast-paced nature of conversation. One core ingredient to turn coordination is the anticipation of upcoming turn ends so as to be able to ready oneself for providing the next contribution. Across two experiments, we investigated two variables inherent to face-to-face conversation, the presence of visual bodily signals and preceding discourse context, in terms of their contribution to turn end anticipation. In a reaction time paradigm, participants anticipated conversational turn ends better when seeing the speaker and their visual bodily signals than when they did not, especially so for longer turns. Likewise, participants were better able to anticipate turn ends when they had access to the preceding discourse context than when they did not, and especially so for longer turns. Critically, the two variables did not interact, showing that visual bodily signals retain their influence even in the context of preceding discourse. In a pre-registered follow-up experiment, we manipulated the visibility of the speaker's head, eyes and upper body (i.e. torso + arms). Participants were better able to anticipate turn ends when the speaker's upper body was visible, suggesting a role for manual gestures in turn end anticipation. Together, these findings show that seeing the speaker during conversation may critically facilitate turn coordination in interaction.

How the Listener's Attention Dynamically Switches Between Different Speakers During a Natural Conversation

The neural mechanisms underpinning the dynamic switching of a listener's attention between speakers are not well understood. Here we addressed this issue in a natural conversation involving 21 triadic adult groups. Results showed that when the listener's attention dynamically switched between speakers, neural synchronization with the to-be-attended speaker was significantly enhanced, whereas that with the to-be-ignored speaker was significantly suppressed. Along with attention switching, semantic distances between sentences significantly increased in the to-be-ignored speech. Moreover, neural synchronization negatively correlated with the increase in semantic distance but not with acoustic change of the to-be-ignored speech. However, no difference in neural synchronization was found between the listener and the two speakers during the phase of sustained attention. These findings support the attenuation model of attention, indicating that both speech signals are processed beyond the basic physical level. Additionally, shifting attention imposes a cognitive burden, as demonstrated by the opposite fluctuations of interpersonal neural synchronization.

Ultrasound measurements of interactive turn-taking in question-answer sequences: Articulatory preparation is delayed but not tied to the response

We know that speech planning in conversational turn-taking can happen in overlap with the previous turn and research suggests that it starts as early as possible, that is, as soon as the gist of the previous turn becomes clear. The present study aimed to investigate whether planning proceeds all the way up to the last stage of articulatory preparation (i.e., putting the articulators in place for the first phoneme of the response) and what the timing of this process is. Participants answered pre-recorded quiz questions (being under the illusion that they were asked live), while their tongue movements were measured using ultrasound. Planning could start early for some quiz questions (i.e., midway during the question), but late for others (i.e., only at the end of the question). The results showed no evidence for a difference between tongue movements in these two types of questions for at least two seconds after planning could start in early-planning questions, suggesting that speech planning in overlap with the current turn proceeds more slowly than in the clear. On the other hand, when time-locking to speech onset, tongue movements differed between the two conditions from up to two seconds before this point. This suggests that articulatory preparation can occur in advance and is not fully tied to the overt response itself.

Turn-taking in human face-to-face interaction is multimodal: gaze direction and manual gestures aid the coordination of turn transitions

Human communicative interaction is characterized by rapid and precise turn-taking. This is achieved by an intricate system that has been elucidated in the field of conversation analysis, based largely on the study of the auditory signal. This model suggests that transitions occur at points of possible completion identified in terms of linguistic units. Despite this, considerable evidence exists that visible bodily actions including gaze and gestures also play a role. To reconcile disparate models and observations in the literature, we combine qualitative and quantitative methods to analyse turn-taking in a corpus of multimodal interaction using eye-trackers and multiple cameras. We show that transitions seem to be inhibited when a speaker averts their gaze at a point of possible turn completion, or when a speaker produces gestures which are beginning or unfinished at such points. We further show that while the direction of a speaker's gaze does not affect the speed of transitions, the production of manual gestures does: turns with gestures have faster transitions. Our findings suggest that the coordination of transitions involves not only linguistic resources but also visual gestural ones and that the transition-relevance places in turns are multimodal in nature. This article is part of a discussion meeting issue 'Face2face: advancing the science of social interaction'.

Timing in Conversation

Turn-taking in everyday conversation is fast, with median latencies in corpora of conversational speech often reported to be under 300 ms. This seems like magic, given that experimental research on speech planning has shown that speakers need much more time to plan and produce even the shortest of utterances. This paper reviews how language scientists have combined linguistic analyses of conversations and experimental work to understand the skill of swift turn-taking and proposes a tentative solution to the riddle of fast turn-taking.

Timing of head turns to upcoming talkers in triadic conversation: Evidence for prediction of turn ends and interruptions

In conversation, people are able to listen to an utterance and respond within only a few hundred milliseconds. It takes substantially longer to prepare even a simple utterance, suggesting that interlocutors may make use of predictions about when the talker is about to end. But it is not only the upcoming talker that needs to anticipate the prior talker ending-listeners that are simply following the conversation could also benefit from predicting the turn end in order to shift attention appropriately with the turn switch. In this paper, we examined whether people predict upcoming turn ends when watching conversational turns switch between others by analysing natural conversations. These conversations were between triads of older adults in different levels and types of noise. The analysis focused on the observer during turn switches between the other two parties using head orientation (i.e. saccades from one talker to the next) to identify when their focus moved from one talker to the next. For non-overlapping utterances, observers started to turn to the upcoming talker before the prior talker had finished speaking in 17% of turn switches (going up to 26% when accounting for motor-planning time). For overlapping utterances, observers started to turn towards the interrupter before they interrupted in 18% of turn switches (going up to 33% when accounting for motor-planning time). The timing of head turns was more precise at lower than higher noise levels, and was not affected by noise type. These findings demonstrate that listeners in natural group conversation situations often exhibit head movements that anticipate the end of one conversational turn and the beginning of another. Furthermore, this work demonstrates the value of analysing head movement as a cue to social attention, which could be relevant for advancing communication technology such as hearing devices.