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.