Waterboarding

"Physical violence usually precedes waterboarding, a sort of softening of the victim’s belly. I was stripped, beaten, deprived of sleep, water and food, and forced to lie on the floor, feet raised with my head slightly below the level of my feet. A piece of soaked cloth was thrown on my face, and fetid water was poured through the cloth to slowly drip into my mouth. This technique causes the fluid to build in your lungs. A key element of waterboarding is the ability to bring the interrogated to the verge of death without actually killing the person. That is what makes a good “interrogator.” I was lucky in this regard; my torturers were masters of their trade....
  
Waterboarding, like other torture methods, makes you talk. You talk a lot; say anything, absolutely anything to get the torture to stop. You throw up a lot, you talk, you scream like a demented person whenever you can, and you throw up again. You give all the answers you think your torturer wants, and more, but not much is true, precise, actionable intelligence. Torture transforms the victim into a fanatical and fierce opponent. Torture taught me the most corrosive diseases of the soul: hatred and revenge." (source)