Source estimation was accomplished using GeoSource, Version 1.0.1, electrical source imaging software (Electrical Geodesics, Eugene, OR). Following Luu, Tucker, and colleagues (Luu, Shane, Pratt, & Tucker, 2009; Poulsen, Luu, Crane, Quiring, & Tucker, 2009), neural source estimates of scalp-derived ERPs were computed using the distributed linear inverse minimum norm approach with sLAURA constraints (Grave de Peralta Menendez, Murray, Michel, Martuzzi, & Gonzalez Andino, 2004). Within GeoSource, the forward model applies a finite difference model (FDM) for accurate computation of the lead field in relation to head tissues. For tissue segmentation, the FDM employs a high-resolution T1-weighted magnetic resonance imaging (MRI) image and whole head computed tomography (CT) scan. Tissue compartments in the default FDM used here were constructed from the Colin27 MRI average (Holmes et al., 1998). A whole-head CT scan of this same individual, whose Talairach-transformed head closely matches the Montreal Neurological Institute average MRI (MNI305), was also used. Within the FDM, conductivity values were 0.25 S/m(Siemens/meter) for the brain, 1.8 S/mfor the cerebral spinal fluid, 0.018 S/m for the skull, and 0.44 S/m for the scalp (Ferree, Eriksen,
