 The "Total Turing test" variation of the Turing test, proposed by cognitive scientist Stevan Harnad, adds two further requirements to the traditional Turing test.The interrogator can also test the perceptual abilities of the subject (requiring computer vision) and the subject's ability to manipulate objects (requiring robotics).A letter published in "Communications of the ACM" describes the concept of generating a synthetic patient population and proposes a variation of Turing test to assess the difference between synthetic and real patients.