The device first appeared in the classic Frank Herbert novel Dune. It was wielded by the hand of Reverend Mother Gaius Helen Mohiam. Her mission was to test the humanity of the son of Lady Jessica and Duke Leto Atreides.
Mohiam harbored resentment toward the Lady Jessica for allowing herself to become pregnant with a son by Leto, thus thwarting plans the Bene Gesserit had to develope the Qwisatz Haderach. The product of this union was a genetic wild card, and one which was outside the control of the Sisterhood. This resentment extended to the young heir of House Atreides, the son Paul.
The gom jabbar was a deadly poisoned needle which would be thrust into the subject, should they fail the test. The test itself involved a neural stimulator capable of exciting nerves via induction to create a pain stimulus. The response to pain is escape, a response normal and consistent to any animal. A human however would be capable of utilizing his own mind to overcome the stimulus. Failing to over ride the stimulus and seeking escape would result in the injection of poison, which would then result in the immediate death of the test subject. Mohiam, in her resentment and desire to punish Lady Jessica, almost pushed Paul over the brink. She pushed him beyond all limits previously set by every female subject, thereby conclusively proving his humanity.
Later along in the Dune
saga, gom jabbar becomes a metaphor for a test with dire results, as well as an expression of veiled threat.