According to her mother, Tatyana Vladimovna, Demkina was a fast learner, but was otherwise a normal child until she was ten years old, at which time her ability began to manifest itself.
[1][2] After stories about Demkina had begun to spread, doctors at a children's hospital in her home town asked her to perform a number of tasks to see if her abilities were genuine.
In one incident she told television-physician Chris Steele that he was suffering from a number of medical conditions, including kidney stones, an ailment of the gall bladder, and an enlarged liver and pancreas.
As a demonstration for the documentary, Demkina was shown wearing her vision-hat and giving diagnoses to people who had previously given descriptions of their specific medical conditions.
She argued that she had required more time to see a metal plate in one subject's skull, that surgical scars interfered with her ability to see the resected esophagus in another, and that she had been presented with two study subjects who had undergone abdominal procedure, but that she had only one abdominal condition on her list of potential diagnoses, leaving her confused as to which one matched the listed condition.
[1][2][4] In a self-published commentary regarding the New York testing performed by the Committee for the Scientific Investigation of Claims of the Paranormal (CSICOP) and CSMMH, Nobel prize winning physicist and parapsychology supporter Brian Josephson criticized the test and evaluation methods used by Hyman and questioned the researchers' motives, leveling the accusation that the experiment had the appearance of being "some kind of plot to discredit the teenage claimed psychic".
[7][8] Hyman responded that the high benchmark used in the testing was necessary due to the higher levels of statistical significance which he says is necessary when testing paranormal claims,[6][9] and that a high Bayes factor was necessary to compensate for the fact that "Demkina was not blindly guessing", but instead "had a great number of normal sensory clues that could have helped increase her number of correct matches".
[9] The Bayes factors used by Hyman were calculated by professors Persi Diaconis and Susan Holmes of the Department of Statistics at Stanford University.
[9][13] After visiting New York, Demkina traveled to Tokyo Electrical University (東京電機大学) in Japan, at the invitation of Professor Yoshio Machi, who studies claims of unusual human abilities.
[1] According to accounts on her personal website, after her experiences in London and New York, Demkina set several conditions for the tests, including that the subjects bring with them a medical certificate stating their health status, and that the diagnosis be restricted to a single specific part of the body – the head, the torso, or extremities – which she was to be informed of in advance.
Natasha claims to have correctly identified that the dog had an artificial device in its back right leg after being specifically directed to look at the animal's paws.
[1] The Tokyo test was reviewed by three Japanese experts: the occult critic Hajime Yuumu, the psychologist Hiroyuki Ishii, and the Tondemo-bon Society skeptic Hiroshi Yamamoto.