[7][8] Over the years, biofeedback as a discipline and a technology has continued to mature and express new versions of the method with novel interpretations in areas utilizing the electromyograph, electrodermograph, electroencephalograph and electrocardiogram among others.

The concept of biofeedback is based on the fact that a wide variety of ongoing intrinsic natural functions of the organism occur at a level of awareness generally called the "unconscious".

The definition reads: Biofeedback is a process that enables an individual to learn how to change physiological activity for the purposes of improving health and performance.

[2] A more simple definition could be: Biofeedback is the process of gaining greater awareness of many physiological functions primarily using instruments that provide information on the activity of those same systems, with a goal of being able to manipulate them at will.

[15] Recognizing the inherent complexity of an organism, information coded biofeedback applies algorithmic calculations in a stochastic approach to identify significant probabilities in a limited set of possibilities.

[57] The pulsative bio-impedance changes directly reflect the total blood flow of the deep structures of brain due to high frequency impedance measurements.

As its name describes, it measures the differences in the color of light reflected back through the scalp based on the relative amount of oxygenated and unoxygenated blood in the brain.

This simple biofeedback device can quickly teach children to wake up when their bladders are full and to contract the urinary sphincter and relax the detrusor muscle, preventing further urine release.

The perineometer, which is inserted into the vagina to monitor pelvic floor muscle contraction, satisfies all the requirements of a biofeedback device and enhances the effectiveness of popular Kegel exercises.

[63] Contradicting this, a 2023 Systematic Review of the literature including eight studies found the scientific evidence to compare pelvic floor muscle training for urinary and anal incontinence after childbirth with and without biofeedback is considered insufficient.

[65] In 2019, the National Institute for Health and Care Excellence recommended against the routine use of use biofeedback in managing urinary incontinence in women who can actively contract the pelvic floor.

Successively smaller volume reinflations of the balloon aim to help the person detect rectal distension at a lower threshold, giving more time to contract the EAS and prevent incontinence, or to journey to the toilet.

[71] Beck published studies of spontaneous electrical potentials detected from the brains of dogs and rabbits, and was the first to document alpha blocking, where light alters rhythmic oscillations, in 1890.

[77] Gibbs, Davis, and Lennox inaugurated clinical electroencephalography in 1935 by identifying abnormal EEG rhythms associated with epilepsy, including interictal spike waves and 3 Hz activity in absence seizures.

[91] The Neuropsychiatric EEG-Based Assessment Aid (NEBA) System, a device used to measure the Theta-to-Beta ratio, was approved as a tool to assist in diagnosis of ADHD on July 15, 2013.

[99] Harrison and Mortensen (1962) trained subjects using visual and auditory EMG biofeedback to control individual motor units in the tibialis anterior muscle of the leg.

[101] Marinacci (1960) applied EMG biofeedback to neuromuscular disorders (where proprioception is disrupted) including Bell Palsy (one-sided facial paralysis), polio, and stroke.

[110] In contrast to Shearn's slight heart rate increases, Swami Rama used yoga to produce atrial flutter at an average 306 beats per minute before a Menninger Foundation audience.

[117] Vaschillo and colleagues (1983) published the first studies of heart rate variability (HRV) biofeedback with cosmonauts and treated patients diagnosed with psychiatric and psychophysiological disorders.

[140] Newton-John, Spense, and Schotte (1994) compared the effectiveness of Cognitive Behavior Therapy (CBT) and Electromyographic Biofeedback (EMG-Biofeedback) for 44 participants with chronic low back pain.

[148][non-primary source needed] Flor (2002) trained amputees to detect the location and frequency of shocks delivered to their stumps, which resulted in an expansion of corresponding cortical regions and significant reduction of their phantom limb pain.

The technology company Philips and the Dutch bank ABN AMRO developed a biofeedback device for retail investors based on a galvanic skin response sensor.

[150] Astor et al. (2013) developed a biofeedback based serious game in which financial decision makers can learn how to effectively regulate their emotions using heart rate measurements.

[151] A randomized study by Sutarto et al. assessed the effect of resonant breathing biofeedback (recognize and control involuntary heart rate variability) among manufacturing operators; depression, anxiety and stress significantly decreased.

In this article the previous studies are evaluated for validity and relevance into how they attribute to the effectiveness of biofeedback being used in tandem with other forms of therapy to produce reduced and manageable anxiety.

The randomized trial by Dehli et al. compared if the injection of a bulking agent in the anal canal was superior to sphincter training with biofeedback to treat fecal incontinence.

[169] Following their reviews, the National Institute for Health and Care Excellence have recommended against the use of biofeedback in the treatment of constipation in children, urinary incontinence in women, and chronic pain.

[69][66][140] Yucha and Montgomery's (2008) ratings are listed for the five levels of efficacy recommended by a joint Task Force and adopted by the Boards of Directors of the Association for Applied Psychophysiology (AAPB) and the International Society for Neuronal Regulation (ISNR).

BCIA certification has been endorsed by the Mayo Clinic,[175] the Association for Applied Psychophysiology and Biofeedback (AAPB), the International Society for Neurofeedback and Research (ISNR),[53] and the Washington State Legislature.

[176] The BCIA didactic education requirement includes a 48-hour course from a regionally-accredited academic institution or a BCIA-approved training program that covers the complete General Biofeedback Blueprint of Knowledge and study of human anatomy and physiology.