A compass reading measures fluctuations in the energy patterns of the skin. The primary feedback mechanism is called GSR for Galvanic Skin Response. GSR is commonly used as a marker for stress.
You place your hand on a cradle and the ZYTO software sends stimuli to the body using digital signatures representative of various alternatives like nutritional supplements. Each stimulus creates a unique GSR response which the software measures and analyzes. Each response indicates a biological preference for the item assessed. Knowing biological preferences help individuals to make better choices about their help; for example, choosing the right nutritional supplements.