Only the upright face with normal configuration produced a
difference wave that was significantly less than 0 at any time-point
in any channel. In this condition, the difference wave recorded at a
large ensemble of centro-parietal, central and fronto-central
electrodes exceeded a P-value of 0.05 (cf. Fig. 2) during extended
contiguous periods. Notably, the topographical distribution of the
difference wave is centered over frontal and central electrodes.
This is typical for auditory MMN (cf. e.g. Garrido et al., 2009;
Näätänen and Alho, 1995), whereas differential potentials produced
by visual-only MMN paradigms are centered at occipital
and parietal sites (cf. e.g. Czigler, 2007; Stefanics et al., 2011).