Fig. 2: Univariate spectral analysis of mid-frontal theta-band oscillations.

A Cluster permutation analysis capturing the difference between the conflict effect at high-intensity and the conflict effect at low-intensity. The solid black line delineates the significant positive cluster with α = 0.05. Bold dots in the top-right headplot represent the region of interest included in the analysis. B Conflict effect computed by subtracting the congruent (C) from the incongruent (I) condition separately for low- and high-intensity. The topographies represent theta-band power distribution within the timing of the significant cluster, which is delineated by a solid black line. C Individual mid-frontal (MF) theta conflict effect. For each participant, the power of the conflict effect was extracted from the area of the significant cluster as delineated in the interaction plot and then ordered according to increasing values. The lighter shade represent a negative conflict effect. D Boxplots illustrating the effect of intensity level on MF theta power of the responses to congruent and incongruent trials. Boxplots show the median (horizontal line within each box), the interquartile range (IQR; the box), and 1.5 times the IQR (whiskers). Outliers are indicated as individual points beyond the whiskers. The difference between intensity conditions was significant (p = 0.003) in incongruent trials but not significant (ns) in congruent trials.