From Cordwainer Smith's story, Scanners Live in Vain, set in the universe of the Instrumentality of Man.
Scanners are highly trained humans who have been cybernetically adapted to be able to endure the Great Pain of Space, in a process known as the Haberman process, which disconnects a large portion of the central nervous system. This process is also used to make Habermen, convicted criminals who were sentenced to a period of servitude in Space.
Scanners have the responsibility of supervising the Habermen in Space. If a Haberman is hurt, or for some reason cannot perform his job, the Scanner will kill him by adjusting the controls on the Haberman's chestbox, the device which regulates a Haberman's bodily functions.