[PS-1.68] Quantifying early electrophysiological effects of audiovisual speech integration

Baart, M. 1, 2

1 BCBL. Basque Center on Cognition, Brain and Language, Donostia - San Sebastián, Spain
2 Department of Cognitive Neuropsychology, Tilburg University, Tilburg, the Netherlands

Early electrophysiological effects of audiovisual (AV) speech integration are characterized by lip-read induced amplitude suppression and latency facilitation of the N1 and P2 peaks, but these effects are not always observed or reported. Here, the robustness of N1/P2 AV integration effects in phonetically congruent audiovisual speech was assessed by analyzing peak values that were taken from published plots and individual data. On average, the N1 and P2 were consistently suppressed and sped-up by lip-read information. To determine whether variability in observed N1/P2 amplitudes and latencies may explain why N1/P2 suppression/facilitation are not always found, additional correlations between peak values and size of the AV integration effects were computed. These analyses showed that N1/P2 peak values correlated with the size of AV integration effects. However, it also became apparent that a portion of the AV integration effects was characterized by larger (instead of smaller) AV than A amplitudes/latencies, which may explain variable findings across the literature. The data also suggested that these amplitude enhancements and latency delays may be related to small/early A-only peaks and large/late AV peaks.