Historic review and definitions

The science of biofeedback was born seventy years ago. Its roots are stretching in the principles of learning, in the field of experimental psychology and neurology.

Long back, before it was established as organized science, various scientists had started to study solitarily the interaction between bodily and psychological functions. In the 1780’s Luigi Galvani had already figured out the important role electric energy played in the muscle movement. He proved with his experiments that every muscular contraction is accompanied by an electric change of muscular activity, which can be traced by a device, studied and recorded.
In 1890, the Italian criminologist Cesare Lombroso started measuring the blood pressure of suspects interrogated by the police. He was the first to suggest that blood pressure could prove useful in monitoring the psychological processes taking place in a person.
In 1930, Edmund Jacobson used an electromyograph to investigate the objective effect of progressive release of chronic accumulated muscular tension upon the level of muscle activity.
Systematic research in the field of biofeedback commenced in the research laboratories of mid ‘30. Around 1940 Ε.Green, H.D. Kimmel, Neal Miller and David Shapiro were among the first psychologists who treated the issue systematically. Biofeedback was initially used to explore animal and human capacity to control the progress of certain functions of the organism, functions which up to that time were considered that could not be placed under voluntary control. The prevailing opinion at that time was that, for instance, gastro-intestinal, cardiac, thermoregulatory functions were totally involuntary. Those early pioneers, hypothesized that if man could gain voluntary control over these functions, as well as others, it would open tremendous perspectives for the treatment of several diseases. Those pioneers suggested that a person could learn to exert direct control over vasoconstriction (vessel constriction) and  prove helpful in the treatment of vasomotor type migraines. The continuous increase of biofeedback’s applications in the control of many physiological functions, eventually led to the successful curative interventions in numerous disorders.
The term biofeedback is relatively new in medical science and means providing the organism with information relating to a biologic signal the organism generated. The term feedback in mechanistic systems indicates a mechanism which receives information on the operation of a mechanistic system, then feeds back this system with information and, usually, gives also an order. For example, a system of this type is the organ measuring the temperature of car coolant. It receives constantly information about this modality and as soon as the measurement exceeds a certain limit, it orders the thermostat to open and circulate the refrigerant in the system. This means that it receives feedback from the environment of the car and gives instructions according to its pre-set regulations.
Similarly, the term feedback is used when we discuss human organic systems or modern robotic systems which “duplicate” human functions. However, in this case information feedback does not imply the typical direct order, but the alteration of a function through voluntary behavioral change.
The term “feedback” was invented by the mathematician Norbert Weiner, who defined it as “a control method of a system achieved by re-entering to the system the results or outcome of its previous performance” (Βirk, 1973). The physiological information fed back can be either realized or not. In either case it is information fed back to the system.
Neal Miller, one of the scientists we mentioned previously, instrumental in the development of biofeedback gives a descriptive definition:

“Biofeedback is the use of modern devices to provide a person with better moment to moment flow of information regarding a certain physiological function which, notwithstanding being under the control of the nervous system, was not  before easily or at all perceived. In servo-systems terminology this information is called feedback. However, when this information refers to biological functions it is called biofeedback”.

Τhere are many definitions and descriptions of biofeedback. Those that define biofeedback with respect to the process adopted and those that define it based on the pursued goal.
In connection to its modus operandi biofeedback could be described as follows:
1. Swartz & Beatty, in 1977, defined: “Biofeedback is a term recently invented which refers to a group of experimental processes, where external stimulus is used to supply the organism with indications, or a picture of the condition of a bodily function. This entire process, usually, takes place during the effort to obtain changes in the measured parameter of the monitored function”.
2. Gaarder & Montgomery, in 1977, specified: “The term biofeedback is mainly used to describe a process. A more accurate term would be external psychophysiological feedback”.
3. Κamiya, in 1971, said about biofeedback application: “Initially, the physiological function we wish to control must be monitored with great precision, so that the occurring changes can be followed moment to moment. The alterations of the psychophysiological modalities must reflect directly upon the trainee who endeavours to bring his function under his control. The person must learn how to affect the physiological changes he monitors”.
With regard to the pursued objectives, biofeedback could be defined in the following terms:
1. Οι Ray, Raczynski, Rogers & Kimball, in 1979, defined:

“The basic and primary goal of biofeedback is to promote and support the self-control of the individual over its physiological functions”.

2. Brown, in 1977, defined: “Biofeedback is the process or technique via which one learns to voluntarily and automatically control the reflexes of the somatic functions he wishes to regulate”.
3. Green, in 1977, defined:

“Biofeedback training is a tool assisting a person to learn to exert psychosomatic self-regulation”.

Let’s see some more general definitions:
1. Birk, in 1973, defined: “As biofeedback can be defined the method employing devices, usually electronic, which detect and enhance bodily functions, in such a manner that deeper information regarding these functions, usually unavailable consciously, become accessible to the trainee and are fed back to him in the form of a reading”.
2. Hassett, in 1978, defined:

“Biofeedback is the process during which the trainee becomes aware of the subtle changes in one’s physiological functions, aiming at realizing the underlying mechanism and bringing them under voluntary control”.

3. Basmajian, in 1979, stated: “Biofeedback can be defined as the technique usually employing electronic equipment to reveal man some of the physiological or pathological incidents taking place inside him. The revelation takes the form of audio or visual signals emitted by the devices, enabling a person to handle these incidents, which without the mechanical aid would remain imperceptible. Learning how to handle them is achieved by elaboration of the signals produced by the devices”.
4. Schwartz & Fehni, in 1982, defined: “Biofeedback uses sensitive electric or electro-mechanic devices in order to measure, process and feedback the ongoing activity of various bodily functions, which the person usually ignores. Through this procedure the patient or trainee has to opportunity to alter his somatic functions or gain beneficial control”.
Conclusively, my definition for biofeedback includes:

Biofeedback is a scientific technique aiming at training you how to desensitize from factors that cause you stress or anxiety, to gain control over certain functions in your organism and thus exploit your inherent potential and be released from health problems, in a manner indeed completely governed by you and your goals.
Or more descriptively:
Once you become cognizant, assisted by a device, of an internal function in your body, of which you were unaware up to that moment, you get the chance to learn how to control and modify this function to a great extent, with the purpose of reaching optimal competence and performance both at internal homeostasis and external activity. This entire process is called biofeedback.


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