# A Game Player Expertise Level Classification System Using Electroencephalography (EEG)
## 3 Experimental Results
### Channel Selection  
A statistical analysis is performed to select the most significant channels for classifying the expertise level. A box-plot for the normalized power spectral densities (PSDs) of the fourteen EEG channel recordings for expert and novice players is shown in Figure 5. The \(+\) symbol indicates the outliers, and the red lines within the box represent the median value. The rectangular box lies in between the first and third quartile of the data values. The results show that on average, expert players have more brain activity as compared to novice players. A \(t\)-test is applied on the PSD values of expert and novice players. A \(t\)-test is used to compare the averages of two results, and the resulting \(t\)-score and \(p\)-value are a measure of the significance of the results. A \(p\)-value of less than 0.005 indicates that the difference between averages is significant and not by chance. The results show that only channels \(F7\), \(O1\), \(F4\) and \(AF4\) are significant for the purpose of player classification with a \(p\)-value \(<0.005\).  
The data of fourteen channels are also analysed on the basis of their activity using brain visualizations. Figure 6 shows the brain activity maps of the average power spectral densities for each channel of an expert and novice player. The colours in the figure represent brain activity as depicted using the PSD, where shades of blue show no or lesser activity, which increases as the colour turns red. It is evident that channels \(F7\), \(O1\), \(F4\) and \(AF4\) are most active during game play of the expert player and do not show a significant activity in the case of the novice player. This further adds credence to the statistical analysis for which the results were presented earlier. This clearly shows that the activities of the frontal and occipital regions are responsible for determining the expertise level in video game play. The frontal lobe is involved in cognitive aspects and decision making. The major portion of the occipital lobe deals with visual functions. The features mentioned in Equation (2)-Equation (14) are used for the selected channels, which are then used to train the set of classifiers as is done for the fourteen channels.  
Figure 5: _Cont._The brain maps are also visualized for the expert and novice player during the resting state. The results are shown in Figure 7. During resting periods, players were instructed to relax, and no mental task was performed. The baseline EEG is recorded with eyes open, and the brain maps show the corresponding activity on the frontal and occipital regions.  
Figure 5: Box-plot for the normalized power spectral densities of fourteen EEG channels for (**a**) expert players and (**b**) novice players. The \(+\) symbol represents the outliers; the rectangular box shows the region between the first and third quartile; and the red line shoes the median values.  
Figure 6: Brain visualization using the average power spectral density for an expert and a novice player.  
Figure 7: Brain visualization for baseline activity using the average power spectral density for an expert and novice player.