" The E-Meter, short for “electropsychometer,” is an “electronic instrument that measures mental state and change of state in individuals,” according to the church. During the process, the preclear, or PC (person getting the auditing), is asked a set of questions or given directions as he holds on to two empty “cans” hooked up to the meter. It is believed that the thoughts in a person’s mind affect the flow of energy between the cans and cause the needle on the dial to move. "

― Leah Remini , Troublemaker: Surviving Hollywood and Scientology