As a hobby, I study psychology. It's like learning the game of chess. Psychology is a mental strategy of development and survival, and people learn to create their own psychology as they grow, be it good or bad. As they do, they use their psychology on you. The ultimate weapon for destroying the opponent's claim, is to say they are crazy or in other words, psychosomatic; All in the head. A manifestation of a delusional mind. To say such a thing to someone who is unsure of their facts can be devastating. It can make them question everything they know and believe in. It can even damage them forever. Another psychosomatic effect is; "The Placebo Effect". This is when a person's physical or mental health appears to improve after taking a placebo or 'dummy' treatment. As per a Harvard Medical review of Placebo, they found placebo can account for up to 50% results in drug trials. However they then go on to theorize that drugs work whilst placebos don't. htt