Biofeedback devices measure a range of physiological variables including brain waves (Electroencephalography), muscle tension (Electromyography) and the electrical conductivity of the skin (galvanic skin response). All of these variables indicate continuums of emotional arousal. It is precisely these measurements that are used in lie-detector machines as they pick up the most subtle of physiological changes – many outside of conscious awareness. Many biofeedback devices exist and create a feedback loop for the user. Having the ability to see these readings, the user can learn to gain control over these physiological measurements by relaxing and seeing (or hearing) measurements rise and fall in response to meditation, self-hypnosis or breathing techniques.
In my private hypnotherapy, psychotherapy and NLP practice, I sometimes elect to use a Galvanic Skin Response (GSR) meter with clients. Galvanic Skin Response (also called electro-dermal response) is a measure of the electrical conductivity of the skin. If I am using a GSR meter within a session, I first connect my clients to device by placing electrodes on two fingers on the same hand. After several minutes, I take an initial baseline reading. During the session, the meter readings will rise and fall in line with the emotional arousal of the client. In essence, the greater the presence of water and salt on the skin, the more conductive of electricity the skin is. Changes in sweat production in the fingertips can occur for a number of physiological reasons; however, there is a correlation between electrical conductivity of the skin and emotional arousal. A higher GSR reading tends to reflect an increase in emotional arousal (whether that emotion be anger, stress, anxiety, and startle response).
Whilst therapists develop great sensory acuity though many client hours experience, the GSR meter provides another tool to provide a clue that something is happening for the client. It is of particular use in hypnoanalysis or regression when the client has accessed an emotional memory and is experiencing it vividly. Whilst abreactions are easily spotted by a therapist, the GSR meter provides an early sign of emotional arousal that may assist the exploration of the traumatic material. The GSR reading can also be useful for testing the change in the client’s emotional arousal regarding phobias before and after the change work has been completed. The client’s responsiveness to hypnotic induction is clearly demonstrated by a falling reading on the GSR meter. The device can, therefore, be used to indicate when the client is deep enough into trance to make suggestions more direct. I recently conducted a hypnotherapy session and during a section about learning new skills, I mentioned being back at school to access and utilise that regressed learning state that children possess (this is a popular approach popularised by the late renowned hypnotherapist Milton Erickson). The meter rose rapidly at this moment although there were no visible changes to skin tone, breathing rate etc. At the end of the session, my client explained that she had enjoyed the experience but mention of the school had reminded her of a time when she had been bullied. Whilst not a significant event, it was nevertheless a demonstration of the usefulness of GSR meters within a therapeutic setting.
Biofeedback devices will never replace the skill of a therapist nor the importance of watching and listening but they can be a useful adjunct to the therapists toolkit in certain situations.