Torture has been shown to be a reasonably good (though not always effective) means of getting people to tell torturers things that they think the torturers want to hear -- whatever the tortured person thinks is most likely to lead to the present cessation of the torture.
Its also been shown to be a fairly poor technique, compared to other alternatives, to get accurate, actionable information.
As the Senate report itself notes, this was the conclusion of the CIA's own work on interrogation techniques prior to 9/11, which was disregarded in the aftermath of 9/11.
Basically, the most effective means is to create a rapport with the subject, and if treated with compassion and respect, eventually some will come around to their captor's side and reveal whatever information they have.
People will say anything to get torture to stop. The interrogators will get the information they want, but they will get so much more bad information made up on the spot to stop the suffering, it's impossible to distinguish between actual intel and the subject telling the interrogator what they want to hear.
It gets even worse when the subject doesn't actually know anything useful. Waterboard most people and they will confess to anything they think will make it stop.
Sure, it worked great during the Inquisition. Evidently they killed a lot of Satanists, witches and wizards. It must've worked -- there don't seem to be any around.
Anyway, that's really counter-intuitive. I mean, I guess I could deal with pain, but losing body parts, skin or eyes? I would talk pretty fast.