The communicative basis of word order by Ted GIBSON (MIT)
Some recent evidence suggests that subject-object-verb (SOV) may be the default word order for human language. For example, SOV is the preferred word order in a task where participants gesture event meanings (Goldin-Meadow et al. 2008). Critically, SOV gesture production occurs not only for speakers of SOV languages, but also for speakers of SVO languages, such as English, Chinese, Spanish (Goldin-Meadow et al. 2008) and Italian (Langus & Nespor, 2010). The gesture-production task therefore plausibly reflects default word order independent of native language. However, this leaves open the question of why there are so many SVO languages (41.2% of languages; Dryer, 2005). We propose that the high percentage of SVO languages cross-linguistically is due to communication pressures over a noisy channel (Jelinek, 1975; Brill & Moore, 2000; Levy et al. 2009). In particular, we propose that people understand that the subject will tend to be produced before the object (a near universal cross-linguistically; Greenberg, 1963). Given this bias, people will produce SOV word order – the word order that Goldin-Meadow et al. show is the default – when there are cues in the input that tell the comprehender who the subject and the object are. But when the roles of the event participants are not disambiguated by the verb, then the noisy channel model predicts either (i) a shift to the SVO word order, in order to minimize the confusion between SOV and OSV, which are minimally different; or (ii) the invention of case marking, which can also disambiguate the roles of the event participants. We test the predictions of this hypothesis and provide support for it using gesture experiments in English, Japanese and Korean. We also provide evidence for the noisy channel model in language understanding in English.
