Description:

The Voice of Experience: Causal Inference in Phonotactic Adaptation

ABSTRACT

Successfully grappling with the widespread linguistic variation of daily life requires speakers to adapt to systematic variation in the environment while discarding incidental variation, based on their prior experience. In the case of phonotactics, speakers’ prior experience is that talkers who differ in their language background are likely to vary in their phonotactic grammars, while talkers who share a language variety are unlikely to do so. I argue that when speakers are exposed to multiple talkers whose phonotactics vary, and those talkers differ in their language background, listeners infer the variation is systematic, and adapt. Conversely, if the talkers share a language background, listeners will infer the variation is incidental, and not adapt.
In two studies, we tested this prediction by exposing listeners to two talkers, each of whom exhibited a different phonotactic constraint. Study 1 examined adaptation in perception: when listeners were exposed to talkers who differed in their language background (1 English vs. 1 French talker), they showed a high degree of adaptation; when the talkers shared a language background (2 English or 2 French talkers), listeners showed a lower degree of adaptation. In a second experiment, listeners showed a high degree of adaptation even when both talkers were non-native speakers with different language backgrounds (Hindi vs. Hungarian), suggesting that listeners make fine-grained distinctions between different non-native language phonotactics.
Study 2 examined adaptation in speech production, using a tongue twister paradigm. Mirroring Study 1, model talkers either shared or differed in their language background. Results were largely inconclusive—there was some evidence of increased adaptation when participants were exposed to model talkers with different language backgrounds, but the effect was inconsistent.
Together, these results suggest that phonotactic adaptation is flexible, but constrained by the causal inferences listeners draw from their prior experience, particularly in perception.