Investigating predictive audiovisual language processing in cochlear implant users

Seeing the interlocutor’s mouth may be particularly relevant for deaf people with cochlear implant (CI users). In an exploratory EEG study, CI users and normal hearing (NH) controls were presented with video recordings of a speaker uttering sentences. Final word predictability was determined by the preceding sentence constraint (high vs low). Mouth visibility (visible vs covered) was manipulated during sentence frames. In preliminary target-locked (word audio onset) ERP analyses on 15 CI users, we found an N400 effect at centro-parietal electrodes (low vs high constraint). The amplitude of the effect was comparable between visible and covered mouth conditions. The interpretation and reliability of the findings will be elucidated by the analyses of the full sample and by the comparison with data from age-matched controls. Future analyses will also focus on pre-target alpha-beta and post-target gamma oscillatory activity to explore how predictive processes are deployed and how multisensory information is integrated, respectively. This will yield a fuller picture of audiovisual speech prediction in people who rely on a poorer auditory signal.