when was polygraph invented

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when was polygraph invented

The polygraph, as a device to measure multiple physiological responses simultaneously, was invented in 1921 by John Augustus Larson, a medical student and police officer. He developed the first practical polygraph that continuously recorded blood pressure, pulse rate, and breathing rate during questioning. Prior to Larson’s invention, there were earlier instruments and contributions to similar concepts, but his was the first integrated and operational polygraph used for lie detection in criminal investigations.

Separately, the term "polygraph" was also used much earlier for a letter- copying device invented by John Isaac Hawkins in 1803, but this is unrelated to the lie detector polygraph.

In summary:

  • Early physiological research and devices related to measuring heart and respiratory activity date back to late 19th century (Angelo Mosso in 1878, Sir James Mackenzie in 1892).
  • Dr. William Moulton Marston developed an early systolic blood pressure test for detecting lies around 1915.
  • John Augustus Larson created the first true polygraph combining multiple physiological indicators in 1921.
  • The modern polygraph was further refined in the 1920s and 1930s by Leonarde Keeler, known as the "Father of Polygraph".

Thus, the polygraph as known today was invented in 1921 by John Augustus Larson.