At P4 (Fig. 3b) we also observed a significant Group x Condition interaction (p < .049) in the time-range covering from 304 ms to 336 ms (Table a Suppl El Mat). Its decomposition revealed significant differences between conditions (Table c Suppl El Mat) in highs (NH vs R and Post) who increased their HEP amplitude, and in lows (Post vs R and IND1), who decreased it.

Moreover, we observed a significant Condition effect (p< .004) regarding both groups (Fig. 4, Table a Suppl El Mat) at Cz (Fig. 4) in a time-window ranging from 288 ms to 360 ms after R-peak. The most extreme differences between the HEPs were between the R and the IND2 conditions, with R exhibiting the higher values of HEP and IND2 the lower ones. Among the other conditions, NH significantly differed from R (288-346) ms range and from B (352-360) ms range. Interestingly, the first and the second halves of the induction (IND1 and IND2) differed from B in different time windows: i.e., (296-320) ms for IND1 and (328-353) ms for IND2.