Psychometric Research - Professional Tools for Hypnotherapy and Psychotherapy Practitioners
GSR Biofeedback Monitor - The theory behind it

The GSR Meter measures a client's Galvanic Skin Response (also known as Electrodermal Response - EDR).  This is simply the electrical conductivity of the skin.  In order to measure this, a very small electrical current (unnoticeable to the client) is passed through the skin from one finger electrode to the other.

The electrical conductivity of the skin is affected by changes in the salt and water in the sweat gland ducts.  These changes occur almost instantaneously in response to certain emotional reactions, the 'fight or flight response' (electrical conductivity increases), and when relaxed (electrical conductivity decreases).  Thus the GSR Meter is able to measure and display a client’s general state of relaxation and immediate emotional reactions.  The depth of relaxation or intensity of emotional response is indicated by the change in reading on the digital display.