In the words of others: ERP evidence of speaker-specific phonological prediction
Prediction models usually assume that highly constraining contexts allow the pre-activation of phonological information. However, the evidence for phonological prediction is mixed and controversial. In this study, we implement a paradigm that capitalizes on the phonological errors produced by non-native speakers to investigate whether speaker-specific phonological predictions are made based on speaker identity (native-vs-foreign). EEG data was recorded from 42 healthy native Italian speakers. Participants were asked to read sentence fragments after which a final word was spoken by either a native- or a foreign-accented speaker. The spoken final word could be predictable or not, depending on the sentence context. The identity of the speaker (native-vs-foreign) may or may not be cued by an image of the face of the speaker. Our main analysis indicated that cueing the speaker identity was associated with a larger N400 predictability effect, possibly reflecting an easier processing of predictable words due to phonological preactivation. As visual inspection of the waveforms revealed a more complex pattern than initially anticipated, we used temporal EFA (Exploratory Factor Analysis) to identify and disentangle the ERP components underlying the effect observed. In the native-accent condition, predictable words elicited a posterior positivity relative to unpredictable words, possibly reflecting a P3b response, which was more pronounced when the speaker identity was cued. In the foreign-accent condition, cueing the speaker identity was associated with a smaller N1 and a larger P3a response. These results suggest that phonological prediction for native- and foreign-accented speakers likely involve different cognitive processes.