Biofeedback of slow cortical potentials. I.

An experiment was performed to investigate the self-regulation of slow cortical potentials (SCP) found in a previous study (Elbert et al. 1979). Seventeen subjects received continuous visual feedback of their actual cortical shift perceptible as a rocket moving across a TV-screen during intervals of 6 sec; subjects had to direct the rocket into one of two goals representing more or less cortical negativity, depending on the pitch of two signal tones. Within two identical experimental sessions feedback trials alternated with test trials without feedback. Highly significant differences of SCP between the two required polarities were demonstrated. The most pronounced differences were observed during test trials without feedback of the second session in which a positive shift below baseline level occurred when positivity (or less negativity) was required.