[Activation-dependent characteristics of the electroencephalogram during visual information--processing: Results of...

EEG signal from fronto-occipital derivation was recorded in 16 Ss during a mental performance test (modified "Konzentrations-Leistungs-Test" including four levels of performance). A balanced changer-over design was used. Interval histograms in four frequency bands (theta, alpha, beta-1 and beta-2 bands) were determined on the basis of peak detection. A total of 44 characteristics were derived and tested (multi-factor analyses of variance, multiple mean comparison and rank tests). Twenty eight of these characteristics were proved to be dependent on activation. In the visual information-processing performances chosen, it could be demonstrated that the intraindividual changes of the spontaneous EEG activity were related predominantly to the perceptual components of the performance. On the other hand, the influence of the performance rate and of the mental-arithmetic itself was of minor relevance. During higher activation an increase in the relative abudance of the theta-band activity was also observed.