We generated forward models using the sensor-space EEG data, in order to view the scalp distribution of discriminating activity for each time window, where Xτ is the matrix comprised of all samples within the 50-ms-wide window from τ − 25 ms to τ + 25 ms. (2)aτ=Xτyτ/yτTyτ This forward model is a normalized correlation between the discriminating component and the data Xτ, and it represents the electrical coupling between them (Goldman et al., 2009; Parra et al., 2002, 2005; Sajda et al., 2010). It allows observation of the progression of the components across the scalp over time.
