Sf authors frequently invoke devices that can tell truth from falsehood a great deal more reliably than real-world polygraphs. The latter are anticipated in "The First Watch" (June 1909 Hampton's Magazine) by Edwin Balmer and William MacHarg, later included in The Achievements of Luther Trant (coll 1910), while their mechanical limitations are considered in G K Chesterton's non-sf Father Brown detective story "The Mistake of the Machine" (October 1913 Pall Mall Magazine).
It is one of the odder features of future society on Earth and Venus in A E van Vogt's The World of Ā (August-October 1945 Astounding; rev 1948; rev vt The World of Null-A 1970) that lie detectors, equipped with AI conversational ability, appear to be standard appliances in all households and hotel rooms. The "schizophraser" of Eric Frank Russell's Dreadful Sanctuary (June-August 1948 Astounding; rev 1951; rev 1963; further rev 1967) is not so much a lie detector as a truth compeller which interferes with the subject's ability to deceive. Such cortical intervention may be physically dangerous, as with the feared Psychic Probe that appears throughout Isaac Asimov's Galactic Empire stories – most damagingly in The Currents of Space (October-December 1952 Astounding; 1952), where its misuse causes deep Amnesia – and the unpleasant "Kindet test" of Brian Ball's Sundog (1965). In sf courtroom scenes the detector provides an immediate measure of witness reliability: it is variously named as the truth meter of Robert A Heinlein's The Star Beast (May-July 1954 F&SF as "Star Lummox"; 1954), the veridicator of H Beam Piper's Little Fuzzy (1962) and the Verifier of James H Schmitz's The Universe Against Her (fixup 1964). John Brunner's The Long Result (1965) distinguishes between open courtroom use of the detector and the "flagrant breach of good manners" of employing it covertly. Courts-martial of the space navy in David Feintuch's Midshipman's Hope (1994) make routine checks of veracity with "P and D", polygraph and truth Drugs (which see for further drug examples).
Criminals naturally hope to beat the lie detector: in Fredric Brown's "Crisis, 1999" (August 1949 Ellery Queen's Mystery Magazine), a Hypnosis-induced Memory Edit not only removes detectable guilt but brings reform since the subjects are in effect no longer criminals. Quick-witted protagonists may be allowed to circumvent the machine by telling literal but misleading truths: "The Best Policy" (July 1957 Astounding) by Randall Garrett revolves around such artful gaming of the system. Many further sf stories make incidental use of lie detectors, for example "Equinoctial" (in Ascents of Wonder, anth 1977, ed David Gerrold) by John Varley. A novel whose central Invention is an infallible lie detector is James L Halperin's The Truth Machine (1996); but in Brian Aldiss's The Primal Urge (1961), UK authorities who have required all citizens to be fitted with forehead-mounted Emotional Registers (making it impossible to conceal Sex-related arousal) draw the line at adding a truth meter, for this would be "a death blow to British diplomacy".
In Fantasy, the ability to detect lies and impersonations has traditionally been a signal that the character so gifted is attuned to the heart of the story; even such a late example as Gene Wolfe's The Sorcerer's House (2010) makes use of this giveaway trope. [DRL]
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