Figure 6. ERP and SPN waves. Top row: Oddball task. Bottom row: Regularity task. Left column: Grand average ERPs from electrode cluster [PO7, O1, O2 and PO8]. Central column:SPN difference waves (symmetry – random). Right column:Topographic difference maps from alcohol (red outline) and placebo (green outline), averaged over the 200-1000 ms window. GFP = Global Field Power (the standard deviation of amplitude across all 64 electrodes).
We also note that all conditions produced a large SPN signal as compared to zero. This is illustrated in three ways in Figure 7. The top row shows SPN waves with 95% CI, the middle row shows SPN amplitude in violin plots, and the bottom row shows prior and posterior plots associated with Bayesian one sample t tests. We can also see that SPNs are normally distributed around the grand average, and present in most participants (at least 23/26, p < 0.001 Binomial test)