A fundamental typological variation in the world’s languages is their basic word order; around 80% of spoken languages are either Subject-Object-Verb (SOV) or Subject-Verb-Object (SVO). Previous work has related this typological pattern to a striking finding in ad-hoc gesture production: across a wide range of languages, people tend to use the order SOV to gesture events with inanimate patients, and SVO orders for those with animate patients (Gibson, Piantadosi, et al., 2013; Hall, Mayberry, & Ferreira, 2013, i.a.). Gibson et al. (2013) interpret this evidence as support for a noisy channel model of communication, under which producers attempt to reduce ambiguity for comprehenders. On the other hand, this pattern might also result from the particular kinds of gestures that people tend to use for different kinds of events (Hall et al. 2013). We conducted two production studies – one in gesture, one using non-iconic written symbols– designed to modify the communication task in different ways. Two main findings emerged from these tests: first, simple modifications to the gesture paradigm can have a profound effect on the orders used: the instructions given in Experiment 1 (gesture) dramatically affected the use of SVO orders, even though participants were gesturing about the same events under the same communicative contexts. Second, there is an apparent association between the physical form of the gestures used to communicate and word order: we found that participants were most likely to use SVO orders in Experiment 1 for animate-animate events when using body-based gestures (avoiding role conflict, as described by Hall et al. 2013); furthermore in Experiment 2 (written symbols), there was no association between SVO ordering and animate-animate scenes (contrary to predictions of the noisy channel model). We conclude that gesturing paradigms, while a striking and naturalistic example of ad-hoc communication dynamics, are also sensitive to the particular modality and task instructions, and as such do not provide straightforward evidence for noisy channel theories of word order typology.
A noisy-channel model of rational human sentence comprehension under uncertain input
