A method of nonprescriptive neurofeedback is described that is based on the brain interacting with its own tonic slow cortical potential. In the absence of any explicit guidance by the clinician, the training depends entirely on the brain's response to the unfolding signal. When this training is performed under optimal conditions in terms of placement and target frequency, there is a bias toward optimal functioning. The brain uses the information for its own benefit. The outcomes of the training are either comparable to or exceed expectations based on conventional electroencelphalogram band-based neurofeedback. Results are shown for a cognitive skills test for an unselected clinical population.