Changes in the N200 and P300 Components of Event-Related Potentials on Variations in the Conditions of Attention in a Brain–Computer Interface System
We put forward the hypothesis that the amplitudes of the P300 and N200 components of visual potentials evoked by flashes of the columns and rows of symbols in a matrix depend on the nature of the task attracting the operator’s attention to target symbol stimuli: 1) simple observation of the flashes of the target symbol; 2) observation with counting the numbers of these flashes and monitoring the success of this operation; 3) observation of the flashes of the target symbol with display of the symbol on a screen when the subject’s attention to this symbol was detected using the EEG as a brain–computer interface. Studies using a group of 17 subjects showed that the maximum amplitudes of the P300 and N200 components of visual potentials were reached to a statistically significant level in the second operator attention regime, which did not require involvement in a brain–computer interface. The second condition showed the largest number of statistically significant differences between the amplitudes of the P300 and N200 components of visual potentials evoked by flashes of target and nontarget symbols. At the same time, the smallest amplitudes of these components and the smallest differences between reactions to the target and nontarget stimuli were seen in conditions of simple observation of the flashes of the target stimuli. These results lead to the conclusion that successful operator functioning in a brain–computer interface does not require the maximal expression of the P300 and N200 components of visual potentials, which probably start to be optimized in the brain–computer interface in the task of controlling external processes, such as display of the target symbol on the computer screen.