## 3 Results  
Considering both EEG features of amplitude and power, there were only very few instances in which EPOC and Brainvision converged in yielding a significant difference in the same direction, from low to high mental state, in the three tasks (7 out of 30 comparisons for amplitude, on a binomial test \(p\) = 0.0003; 5 out of 30 comparisons for power, on a binomial test \(p\) = 0.0052). The convergent comparisons are shown in bold in Table 1A,B. \begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline  & & \multicolumn{6}{c}{**(B)**} \\ \hline  & \multicolumn{6}{c}{**EPOC**} & \multicolumn{6}{c}{**Brainvision**} \\ \hline \multirow{2}{*}{**Band**} & \multicolumn{2}{c}{**Mental State**} & \multirow{2}{*}{**z**} & \multirow{2}{*}{\(P\)} & \multirow{2}{*}{\(\mu^{2}\)} & \multicolumn{2}{c}{**Mental State**} & \multirow{2}{*}{**z**} & \multirow{2}{*}{\(p\)} & \multirow{2}{*}{\(\mu^{2}\)} \\ \cline{2-2} \cline{5-10}  & **Low** & & & & & & **Low** & & **High** & & \\ \hline \multicolumn{10}{c}{(IAPS, Valence)} \\ Delta & **1.60** & **2.69** & \(-\)**3.02** & **0.003** & **0.65** & **14.10** & **12.14** & **2.79** & **0.005** & **0.56** \\ Theta & 0.47 & 0.98 & \(-\)3.05 & 0.002 & 0.67 & 6.29 & 6.24 & 0.47 & 0.638 & 0.02 \\ Alpha & **0.96** & **1.40** & \(-\)**3.11** & **0.002** & **0.69** & **16.98** & **17.95** & \(-\)**1.57** & **<0.001** & **0.12** \\ Beta & 0.24 & 0.33 & \(-\)3.22 & 0.001 & 0.74 & 10.59 & 10.68 & \(-\)0.18 & 0.861 & 0.00 \\ Gamma & 0.01 & 0.01 & 0.00 & 1.000 & 0.00 & 9.08 & 8.50 & 3.30 & \(<\)0.001 & 0.78 \\ \multicolumn{10}{c}{(n-Back I,3,5)} \\ Delta & 3.68 & 2.70 & 2.35 & 0.019 & 0.39 & 4.63 & 3.72 & 1.41 & 0.158 & 0.14 \\ Theta & 0.99 & 1.10 & \(-\)1.82 & 0.069 & 0.24 & 2.50 & 2.42 & 0.47 & 0.638 & 0.02 \\ Alpha & 1.67 & 1.65 & 0.03 & 0.975 & 0.00 & 2.12 & 1.97 & 1.16 & 0.245 & 0.10 \\ Beta & 0.67 & 0.69 & \(-\)0.25 & 0.807 & 0.00 & 1.17 & 1.34 & 3.18 & 0.001 & 0.72 \\ Gamma & 0.14 & 0.15 & \(-\)1.70 & 0.090 & 0.21 & 1.09 & 1.24 & \(-\)2.67 & 0.008 & 0.51 \\ \multicolumn{10}{c}{(n-Back I,4,6)} \\ Delta & 10.48 & 2.64 & 3.30 & \(<\)0.001 & 0.78 & 2.53 & 2.39 & 0.66 & 0.510 & 0.03 \\ Theta & 2.45 & 1.05 & 3.30 & \(<\)0.001 & 0.78 & 2.37 & 2.79 & \(-\)2.61 & 0.009 & 0.49 \\ Alpha & 4.79 & 1.50 & 3.30 & \(<\)0.001 & 0.78 & 1.42 & 1.69 & \(-\)2.73 & 0.0 Sensitivity to detect individual significant changes between low and high mental state level in any frequency band and any direction were comparable in both systems for most tasks and states except ANEW where EPOC performed sensibly worse, picking up changes only for Gamma as opposed to all electrodes as in Brainvision, and yielding about half of the effect size on average. Additionally, the performance of EPOC and Brainvision showed equally few effects for the 1,2,3 version of the n-Back task. In terms of absolute measurement of EEG signal, EPOC demonstrated a variable performance as compared to Brainvision depending on the task. EPOC's efficiencies for the tasks were computed as the ratio of EPOC's measurements over Brainvision measurements; they are represented graphically in Figure 2. When compared to Brainvision measurements in ANEW (see Figure 2A), EPOC's efficiency in measuring amplitude changes was modest for arousal, generally hovering around 40-20% and below 10% for Gamma, and low for valence 30-20% and below 5% for Gamma. In the IAPS (see Figure 2A), EPOC's efficiency in measuring power was even lower for both arousal and valence across all frequencies ranging between 20 and 10%, with Gamma being below 2% or undetected as compared to Brainvision measurements. However, EPOC's efficiency was much higher in the n-Back task (See Figure 2B) whereby it was variedly distributed across bands going from low/modest (i.e., Gamma) to medium (i.e., Theta, Beta), on par with or even exceeding (i.e., Alpha and Beta) Brainvision. Notably, in the 2,4,6 n-Back high load state EPOC outperformed Brainvison in all frequency bands except Gamma.