The idea to use electroshock on humans came to Ugo Cerletti when he observed how pigs were administered electric shocks to induce an anesthetized state before being butchered. Inspired by this, he persuaded two colleagues to assist him in developing a method and apparatus for delivering brief electric shocks to human subjects.
A "positive side effect" of the treatment was retrograde amnesia, which involved a loss of memory for events immediately preceding the shock, including the perception of the treatment itself. This side effect meant that patients could not recall the treatments, resulting in no negative feelings toward the procedure.