Psycho galvanometers are devices that measure changes in a person's skin resistance, which can indicate emotional arousal. Synonyms for these devices could include electrodermal activity sensors, skin conductance sensors, or skin response devices. While psycho galvanometers are commonly used in research settings to study emotions and stress responses, these devices are also used in lie detection tests and as a form of biofeedback therapy. Regardless of what they are called, their purpose remains the same - to measure the subtle electrical changes that occur on the skin's surface in response to various stimuli.