Lasso of Truth period before, during and after World War I, on understanding and perfecting the systolic blood-pressure test while working on his Ph.D. in psychology at Harvard University. Blood pressure was one of several elements measured in the polygraph tests that were being perfected since as far back as Italian criminologist Cesare Lombroso, in 1895. Marston's wife, psychologist and lawyer Elizabeth Holloway Marston, one of his inspirations for the Wonder Woman character, also played a key role in his lie detector research. But the lie detector had nothing to do with Marston's creation of the Magic Lasso. Wonder Woman's "Magic Lasso" or
Polygraph device's primary advocate, lobbying for its use in the courts. In 1938 he published a book, "The Lie Detector Test", wherein he documented the theory and use of the device. In 1938 he appeared in advertising by the Gillette company claiming that the polygraph showed Gillette razors were better than the competition. A device recording both blood pressure and breathing was invented in 1921 by John Augustus Larson of the University of California and first applied in law enforcement work by the Berkeley Police Department under its nationally renowned police chief August Vollmer. Further work on this device was done