13 A camera that detects liars. According to New Scientist

(January 2, 2002), a new thermal imaging camera that detects small temperature changes is now being used as a polygraph device. The United States Department of Defense Polygraph Institute (DDPI) claims that the camera can detect liars correctly 75% of the time by monitoring the temperatures of their faces. Give the null hypothesis for testing the claim made by the DDPI.