Learning to Expect the Unexpected: Speech Disfluencies, Expectancy, and the N400 Effect
Storch, Barbara F.
- Prior work has indicated that speech disfluencies are produced in a systematic fashion. Specifically, speakers are more likely to produce a speech disfluency before an unexpected word or phrase. This patterned production of disfluencies may lead listeners using disfluencies as a signal to “expect the unexpected” continuation (Arnold & Tanenhaus, 2011). Disfluencies have been shown to attenuate the... read moreN400 effect in previous studies (Corley, MacGregor, Donaldson, 2007). Additionally, prior research has shown that listeners can change the way they use disfluencies based on given prior knowledge about the speaker (Bosker et al., 2014). The present study aims to examine first whether people can learn if disfluencies are a reliable signal, and then to examine the nature of the attenuation of the N400 effect following disfluencies. We adopted a between-subjects design in which one speaker uses disfluencies reliably to signal an unexpected completion, one uses disfluencies in an unreliable, unsystematic fashion. The preliminary data reported here shows a statistically significant N400 effect of cloze, as well as a significant N400 effect of fluency. These results indicate a proof of concept of the classic N400 effect for cloze, and signals that listeners are utilizing disfluencies in a systematic fashion to aid in prediction, although the nature of that utilization is not yet clear. The present sample size is not large enough to fully examine both the interaction between expectancy and fluency as well as the between subjects manipulation, which is a limitation of the present results.read less