Biofeedback is a form of alternative medicine that involves measuring a subject's quantifiable bodily functions such as blood pressure, heart rate, skin temperature, sweat gland activity, and muscle tension, conveying the information to the patient in real-time. This raises the patient's awareness and conscious control of their unconscious physiological activities.

By providing the user access to physiological information about which he or she is generally unaware, biofeedback allows users to gain control of physical processes previously considered an automatic response of the autonomous nervous system. Interest in biofeedback has waxed and waned since its inception in the 1960s; it is, however, undergoing something of a renaissance during the early 21st century, which some experts attribute to the general rise in interest about all alternative medicine modalities. Neurofeedback, a type of biofeedback treatment, has also become a popular treatment for Attention Deficit/Hyperactivity Disorder (ADHD); electromyogram biofeedback, used for muscle tension, has been widely studied and is currently accepted as a treatment for incontinence disorders, and small biofeedback machines are becoming available for a variety of uses in the home. The role of biofeedback in controlling hypertension is also becoming recognised. [ [ Device-Guided Paced Breathing Lowers Blood Pressure - Blood Pressure ] ]

The Association for Applied Psychophysiology and Biofeedback, or AAPB is the non-profit scientific and professional society for biofeedback, much akin to the American Psychological Association.

Origin of biofeedback

Neal Miller, a psychologist and neuroscientist who worked and studied at Yale University during the middle of the 20th century, is generally considered the father of modern-day biofeedback. He discovered the basic principles of biofeedback by applying his theory that classical and operant conditioning were both the result of a common learning/conditioning principle. Miller hypothesized that any measurable physiological behavior within the human body would respond in some way to voluntary control. His team found that by stimulating the pleasure center of a paralyzed rat's brain with electricity thereby rewarding them without something that might make them act in some way to make the physiological changes, it was possible to train them to control phenomena ranging from their heart rate to their blood pressure and body temperature. Until Miller's research, it was believed by the scientific community that physiological processes (e.g. heart rate) were solely under the control of the autonomic nervous system and not responsive to conscious effort [ [,4273,4387089,00.html Guardian Unlimited | Archive Search ] ] . Miller later retracted many of his claims because he was unable to replicate much of the data that he had published with Leo DiCara,the primary graduate assistant with whom he published all of his biofeedback results. Leo DiCara, after receiving a tenured position at the University of Michigan because of his groundbreaking work with Miller committed suicide one year later.

The hypotheses proposed by the Miller group make up one of three major approaches to understanding the mechanism of self-regulation of the body. Voluntary control of the autonomic nervous system had previously been considered impossible, something only controlled by conditioning.

Other threads of inquiry that led to the present-day "biofeedback" emerged from clinical attempts to use mind/body self-regulation techniques in healthcare. Dr. Elmer Green of the Menninger Foundation performed some of the original research on the limits of human self-regulation of processes normally controlled by the unconscious mind and then applied these techniques successfully to the treatment of migraine headaches and hypertension. Dr. Barbara Brown was the first to coin the word "biofeedback" during the early days of experimentation, at the same time as the formation of the Biofeedback Research Society. Other early pioneers were interested in the study of "consciousness" and looked towards electroencephalogram (EEG) self-regulation as a way to approach mind vs. brain dichotomy (see the work of Dr.Kamiya). Other early efforts in the field of biofeedback were directed toward the examination of claims by yogis and others who meditate who were able to demonstrate mind/body control and markers of states of consciousness. [ [ Harvard Gazette] ] See Elmer Green et al "Beyond Biofeedback" and Barbara Brown "Stress & The Art of Biofeedback" for some early writings. The Biofeedback Research Society evolved into the Biofeedback Society of America and more recently the Association for Applied Psychophysiology and Biofeedback.

Efficacy ratings

The Association for Applied Psychophysiology and Biofeedback has developed the following criteria for setting the level of evidence for efficacy [ [ AAPB efficacy rating criteria] ] .

Level 1: Not empirically supported

Supported only by anecdotal reports and/or case studies in non-peer reviewed venues.

Level 2: Possibly efficacious

At least one study of sufficient statistical power with well identified outcome measures, but lacking randomized assignment to a control condition internal to the study.

Level 3: Probably efficacious

Multiple observational studies, clinical studies, wait list controlled studies, and within subject and intrasubject replication studies that demonstrate efficacy.

The following biofeedback protocols have received a level 3 efficacy rating: alcoholism/substance abuse, arthritis, chronic pain, epilepsy, fecal elimination disorders, pediatric migraines, insomnia, traumatic brain injury, vulvar vestibulitis [ Yucha, C. & Gilbert, C. (2004) Evidence-Based Practice in Biofeedback and Neurofeedback] ] .

Level 4: Efficacious

* In a comparison with a no-treatment control group, alternative treatment group, or sham (placebo) control utilizing randomized assignment, the investigational treatment is shown to be statistically significantly superior to the control condition or the investigational treatment is equivalent to a treatment of established efficacy in a study with sufficient power to detect moderate differences, and
* The studies have been conducted with a population treated for a specific problem, for whom inclusion criteria are delineated in a reliable, operationally defined manner, and
* The study used valid and clearly specified outcome measures related to the problem being treated and
* The data are subjected to appropriate data analysis, and
* The diagnostic and treatment variables and procedures are clearly defined in a manner that permits replication of the study by independent researchers, and
* The superiority or equivalence of the investigational treatment have been shown in at least two independent research settings.

Biofeedback treatment protocols for anxiety, ADHD, hypertension, TMD, urinary incontinence in males, and migraine, cluster, and tension headaches have all received level 4 efficacy ratings.

Level 5: Efficacious and specific

The investigational treatment has been shown to be statistically superior to credible sham therapy, pill, or alternative bona fide treatment in at least two independent research settings.

Biofeedback treatment protocol for urinary incontinence in females has been given a level 5 efficacy rating.

Major Biofeedback Modalities


An electromyograph, or EMG is the one of the most commonly used modalities in biofeedback treatment. An EMG in a biofeedback setting typically uses electrodes in order to measure muscle action potentials. These action potentials result in muscle tension. The patient can learn to recognize the way tension subjectively feels by using the objective EMG readings, and as a result learn to control the muscle tension. EMG is used as a relaxation technique to ease tension in the muscles causing backaches, neck pain, TMD, incontinence, and tension, migraine, and cluster headaches. EMG is also used in the process of muscle rehabilitation, such as in cases of paralysis resulting from Cerebral Palsy, stroke, and incomplete spinal cord lesions.

Feedback Thermometer

A thermistor attached to the subject's digits or web dorsum measures the subject's skin temperature. Because there is a correlation between a drop in body temperature and the patient's experience of stress, a low temperature reading indicates the need to begin relaxation techniques. Temperature biofeedback can also help in treating certain circulatory disorders, such as Raynaud's disease, and can reduce the frequency and severity of migraines. The physiological processes which are being trained in this modality are vasoconstriction and vasodialation, where blood vessel size is a result of the contraction and relaxation of smooth musculature in the vessel walls. The mechanism being trained in warming exercises is a beta-adrenergic vasodilator mechanism [ [;49/5/1196Beta-adrenergic vasodilator mechanism in the finger] ] .


In electrodermograph training, sensors measure the activity of a patient's sweat glands. The amount of electrical resistance measured on the skin indicates the level of anxiety. This information can then be used to treat emotional disorders such as phobias, anxiety and stuttering. The best-known use of this method of biofeedback is in polygraph machines. Galvanic skin response meters are currently gaining popularity in hypnotherapy and psychotherapy practices, so subtle physiological changes that indicate emotional arousal can be more easily detected.


An electroencephalograph, or EEG monitors the activity of brain waves. These brain waves correspond to different mental states, such as wakefulness (Beta waves), relaxation (Alpha waves), calmness (Theta waves), and light sleep and deep sleep (Delta waves). EEGs are useful in the treatment of anxiety and ADHD, in which the protocols have been awarded a level 4 efficacy rating by the AAPB.


Photoplethysmographs, or PPGs, in biofeedback are used to measure peripheral blood flow, heart rate, and heart rate variability(HRV). To measure HRV, PPGs measure the varying distances between heart beats, also known as the interbeat interval (IBI). This data guides users in finding a breathing pattern that increases their variability. PPGs are also helpful in biofeedback treatment for some types of cardiac arrhythmias.


A pneumograph measures abdominal/chest movement (as when breathing), usually with a strain gauge. They are used to detect breathing rate, and correct ineffective breathing patterns such as thoracic breathing, reverse breathing, and apnea. They are also often used in conjunction with a PPG in HRV training.


A capnometer measures end-tidal CO2 with an infrared detector. All biofeedback training that employs the use of a capnometer aims at normalizing end-tidal CO2 at 5%. Capnometric biofeedback is useful in the treatment of hyperventilation syndrome. During hyperventilation, end-tidal CO2 lowers from a normal level of 5% to 2.5%.


Hemoencephalography, or HEG biofeedback is a method of functional infrared imaging that indirectly measures neural activity in the brain. There are two known types of HEG, passive infrared (pIR) and near infrared (nIR). [] Near infrared HEG measures the differences in color of light reflected back through the scalp, based on the relative amount of oxygenated and unoxygenated blood in the brain. Passive infrared measures the amount of heat that is radiated by the scalp at various locations of interest.

Biofeedback in electronic games

Charles Wehrenberg implemented "competitive-relaxation" as a gaming paradigm with the "Will Ball Games" circa 1973. In the first bio-mechanical versions, comparative GSR inputs monitored each players' relaxation response and moved the "Will Ball" across a playing field appropriately using stepper motors. In 1984 Wehrenberg programmed the "Will Ball" games for Apple II computers. The"Will Ball" game itself is described as pure "competitive-relaxation"; "Brain Ball" is a duel between one player's left and right brain hemispheres; "Mood Ball" is an obstacle based game; "Psycho Dice" is a psycho-kinetic crap game. [ Charles Wehrenberg "Will Ball", Solo Zone, San Francisco, 1995/2001 ISBN 1-886163-02-2]

Biofeedback in art

Biofeedback data and biofeedback technology are used by Massimiliano Peretti in a contemporary art environment, the Amigdalae project. This project explores the way in which emotional reactions filter and distort human perception and observation. During the performance, biofeedback medical technology, such as the EEG, body temperature variations, heart frequency, and galvanic responses, are used to analyze the audiences' emotions while they watch the video art. Using these signals, the music changes so that the consequent sound environment simultaneously mirrors and distorts the viewer's emotional state. [ [ under changes ] ] [ [ Scope New York Home ] ]

More information is available at the website of the CNRS French National Center of Neural Research [] .

David Rosenboom has worked to develop musical instruments that would respond to mental and physiological commands. Playing these instruments can be learned through a process of biofeedback.


Further research is needed in many applications of biofeedback therapy. While many scientific studies have examined neurofeedback as a treatment for ADHD, [ [ Neurofeedback: an alternative and efficacious trea... [Appl Psychophysiol Biofeedback. 2005 - PubMed Result ] ] [ [ Effect of neurofeedback training on the neural sub... [Neurosci Lett. 2006 - PubMed Result ] ] [ [ Neurofeedback treatment of children with attention... [Prilozi. 2005 - PubMed Result ] ] [ [ Neurofeedback in adolescents and adults with atten... [J Clin Psychol. 2005 - PubMed Result ] ] [ [ The effectiveness of neurofeedback and stimulant d... [Appl Psychophysiol Biofeedback. 2004 - PubMed Result ] ] it is generally viewed as a "promising" rather than a "proven" treatment modality [ [ Biofeedback Technology: A Prospectus ] ] . EEG biofeedback as a treatment for ADHD is also viewed with skepticism in some areas of the medical community [ [ Frequently Asked Questions ] ] [ [ Medem: Medical Library: ADHD — Unproven Treatments ] ] . Furthermore, some believe that the use of biofeedback for stress and anxiety is an expensive method of treatment which could be replaced with simple relaxation training, meditation, and self-hypnosis.

External links

* [ Biofeedback FAQ from the Mayo Clinic]
* [ The Association for Applied Psychophysiology and Biofeedback (AAPB)]
* [ The Israeli Association for Applied Psychophysiology and Biofeedback]

University project

* [ University of Vienna : cours Biomedical Engineering, Electromyography (EMG)]
* [ Hardware, EMG (Escuela de Ingeniera de Antioquia, Colombie)]
* [ Electroencephalographe,EEG, Wireless (Cornell University, Ithaca, NY, USA)]

Open source project

* [ Stress et biofeedback, bioamplificateur, EMG (French)]
* [ OpenEEG project]

Modern research on meditation

* [ Collaboration and research partnerships between modern science and Buddhism]
* [ The Science and Clinical Applications of Meditation, Colloque 2005]
* [ Colloque Investigating mind]

Notes and references

Wikimedia Foundation. 2010.

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