Problems in heart rate and alpha electroencephalographic feedback. Is the control over the feedback stimulus meaningful?

Abstract

When a subject has demonstrated successful control over a feedback stimulus, the experimenter should not interpret this to mean that the subject has learned a specific correlated physiological function. Data from two types of experiments — attempted heart rate stoppage and alpha electro-encephalographic feedback control — demonstrate some of the problems. The apparent heart stoppage of one subject was caused by the decrease in arterial pressure which occurred during a Valsalva procedure. The successful control over feedback stimuli during an EEG feedback study led to confused results: in this case the alpha criterion was too broad and was satisfied by different alpha frequencies, amplitudes, phase relations, and toposcopic distributions. Grouped subject data would only confuse the interpretation further. Suggestions to avoid some EEG feedback pitfalls are given.