Fig. 4.

Waveform selection using PCA and cross-correlation analysis. For each stimulus modality (columns), the first three principal components PC1-3 (rows) are re-projected onto the average EEG timeseries to assess goodness-of-fit. The component’s waveforms are in red, and the average EEG timeseries are in black. Vertical dotted lines denote the point of stimulus application. For each stimulus modality, PC2 was selected as the stimulus-evoked template as it has the best fit to the EEG data (quantified using cross correlations – see main text), demonstrating clear correspondence to a positive or negative deflection. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)