1. A device for determining changes in the electrical resistance of the skin in response to emotional stimuli.
2. Any electrical circuit designed to measure the psychogalvanic response.

The reading of the degree of change in skin resistance, that is, changes in sweat gland secretion, detected by a sensitive galvanometer may be made directly and visually, or a permanent registration of the psychogalvanic response can be made by means of an ink trace or photographic recording.