(Photo: Arnd Wiegmann/Reuters)

John Augustus Larson, a Nova Scotia-born police officer with a PhD in physiology, made a name for himself hunting for liars. Today, the inventor of the modern lie detector would have been 121 years old, and his polygraph machine has become, if no longer a staple of law enforcement, a recurring dramatic device in countless TV crime procedurals and movies.

Larson was born in 1892 in Shelburne, about 200 kilometres southwest of Halifax, before leaving Canada with his family as a young boy to resettle in New England.

He was fascinated by biology and the science of forensics, eventually studying physiology at the University of California in Berkeley. That's where he first tried to develop a machine that could read physiological responses — respiration rates, pulse rates and blood pressure — during the interrogation of a subject.

The Berkeley Police Department hired Larson onto the force and in 1921, he developed his most famous apparatus, the polygraph (Greek for "many writings"), which simultaneously scratched out multiple lines on a rotating ream of paper that were used to indicate things like breathing and cardiovascular changes in reaction to an examiner's questions. Evidence of deception was based on a pattern of increased physiological behaviour. 

Leonarde Keeler later refined Larson's device by adding components that could measure the electrical response from skin glands.

The polygraph was credited with helping to solve many criminal cases after it debuted, but its validity as a true lie-detecting tool for law enforcement has been discredited over the years. The American Psychological Association said that "most psychologists" agree there isn't much science to back a polygraph test's ability to discern truth from lies.

"An underlying problem is theoretical: There is no evidence that any pattern of physiological reactions is unique to deception," the association said in a 2004 paper. "An honest person may be nervous when answering truthfully and a dishonest person may be non-anxious."

The case of Floyd Fay has often been cited by polygraph detractors. Fay was accused of murdering a convenience store clerk in 1978. He volunteered for a polygraph test but failed twice and the results were used against him in court. Fay was sentenced to life in prison and served two years before the real killers were eventually found. Fay was then released and received $25,000 compensation for the time he spent behind bars.

Even though use of polygraph tests has not been as widely accepted by law enforcement in Europe as it has been in Canada and the U.S., the device has nevertheless been embraced by Hollywood, and it's a recurring trope of film and TV thrillers. Check out some of the videos embedded below for some memorable great lie-detection scenes: