The LENS, or Low Energy Neurofeedback System, uses a very low power electromagnetic field, like the ones that surround digital watches and wires in the wall, to carry feedback to the person receiving it. The feedback travels down the same wires carrying the brain waves to the amplifier and computer. Although the feedback signal is weak, it produces a measurable change in the brainwaves without conscious effort from the individual receiving the feedback. The LENS software allows the EEG signals that are recorded at the scalp to control the feedback.
Neurofeedback uses a feedback frequency that is different from, but correlates with, the dominant brainwave frequency. When exposed to this feedback frequency, the EEG amplitude distribution changes in power. Most of the time the brain waves reduce in power; but at times they also increase in power. In either case the result is a changed brainwave state, and much greater ability for the brain to regulate itself.