In spoken interactions, interlocutors carefully plan and time their utterances, minimising gaps and overlaps between consecutive turns.1 Cross-linguistic comparison indicates that spoken languages vary minimally in their turn timing.2 Pre-linguistic vocal turn taking has also been attested in the first six months of life.3 These observations suggest that the turn-taking system provides a universal basis for our linguistic capacities.4 It remains an open question, however, whether precisely-timed turn taking is solely a property of speech. It has previously been argued that, unlike speakers, signers do not attend to the one-at-a-time principle, and instead form a collaborative turn-taking floor with their interlocutors, thus having a higher degree of social tolerance for overlap.5 But recent corpus analyses of Sign Language of the Netherlands (NGT) have revealed that, although simultaneous signing is more frequent in NGT than overlapping speech in spoken languages, the additional overlap may come as a consequence of having larger and thus slower articulators.6 The beginnings and ends of signed utterances are bookended by preparatory and retractive movements — phonetically necessary articulations that do not add to the interpretation of the utterance.7 When turn timing is calculated on the basis of stroke-to-stroke turn boundaries, NGT turn timing and turn overlap are consistent with documented averages for spoken turn taking.6 This paper presents new experimental evidence supporting the psychological reality of stroke-to-stroke turn boundaries for signers by using an adapted button-press paradigm, originally developed for measuring spoken turn prediction.8 Our results indicate that signers indeed anticipated turn boundaries at the ends of turn-final strokes. These findings are the first to experimentally support the idea that signers use something like stroke-to-stroke turn boundaries to coordinate conversational turns. They also suggest that linguistic processing, represented by participant age and age of acquisition, plays a role in the ability to use precisely-timed turns in conversation.