And the answer: Lasso of Truth.
Wonder Woman wrangles enemies with her signature Lasso of Truth—and while the lasso is fictional, her weapon is based on the invention of the first polygraph test. By measuring systolic blood pressure, the creator of Wonder Woman was able to build the first functional lie-detecting polygraph test. William Moulton Marston was a lawyer and psychologist who integrated his scientific discoveries into the Wonder Woman comics.
The Lasso of Truth is a longstanding emblem of Wonder Woman’s virtue and integrity in the world of superheroes. Interestingly, though, the weapon was introduced after Wonder Woman’s superhero debut. A few issues in, it was creator William Moulton Marston that bestowed Wonder Woman with her Lasso of Truth. According to the series, the Lasso originally comes from the girdle of Aphrodite, the Greek goddess of love. Powerfully, Marston manipulates the symbol to become one of unrestrainable power, rather than love or seduction.
The Lasso of Truth offers Wonder Woman limitless capabilities. Due to its godly-origins, the rope can stretch endlessly, and take on practically any foe. The Lasso’s only limitations lie in the mind of its user, so wherever Diana Prince bids it to go, the Lasso of Truth must obey.
Outside of the realm of superheroes, though, creator Marston was working on larger psychological projects. In the period before, during and after World War I, Marston created the systolic blood-pressure test while working on his Ph.D. in psychology at Harvard University. Marston's wife, Elizabeth Holloway Marston, suggested a connection between emotion and blood pressure to William by observing that, when she got mad or excited, her blood pressure seemed to climb. Marston’s wife was one of his inspirations for the Wonder Woman character and played a key role in his lie detector research.
Learn more about Wonder Woman here.