Was John A Larson the only inventor of the lie detector test?

No, John A. Larson was not the only inventor of the lie detector test. While he is credited with developing the modern polygraph in the 1920s, other inventors, such as William M. Marston, also contributed to the concept of measuring physiological responses to determine truthfulness. Larson's work built on earlier ideas and technologies, making him a significant figure in the development of the lie detector but not the sole inventor.