The Truth Machine

Feb 2, 2026

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Leonarde Keeler, inventor of the modern polygraph, first showcased his device in a courtroom on 2nd February, 1935. The wooden box, which measured physiological responses like blood pressure and respiration, took the stand alongside him, and, while Keeler emphasized the machine wasn’t infallible, he later told journalists assembled outside the venue that his invention would soon revolutionise criminal justice.

Keeler’s innovations built upon earlier work by others, including Scottish cardiologist James McKenzie, who created a device to detect heart arrhythmias, and Dr. William Moulton Marston, who later linked blood pressure changes to emotional responses - and, inspired by his "truth-telling" research, would go on to create Wonder Woman. But Keeler’s talent for self-promotion, using dramatic applications of his polygraph, made his name, and cemented the device’s reputation as a “lie detector” (a term he never actually used).

In this episode, Arion, Rebecca and Olly discover how the polygraph - now discredited as evidence in US courts - once put a Death Row inmate to the electric chair; reveal how Keeler’s mentors gradually drifted away from the ‘monster’ they had created; and explain how the men who invented the ‘truth machines’ of the 20th century had an uncanny talent for meeting their wives at work…