When writing a character like the Hunter of Voramis, bad-ass half-demon assassin, it's all but guaranteed that there will be some form of torture involved (live by the sword, and all). Even more so when he's visiting a mountaintop temple that is home to a wonderful organization known as the "Masters of Agony"—professional sadists and torturers.
(Yes, The Last Bucelarii (Book 4): Anamnesis is going to be a wild ride!)
As you know, I like to do a lot of research for the stories I write. I delved into a lot of the medieval torture methods, using some of the cruelest forms of torture used by the Inquisition as well as coming up with a few of my own.
(Can you say "iron cage"—if you've read the Hunter's stories, you know how brutal this is…)
My research led me to a fascinating article on Psychology Today, that explained how Cognitive Behavioral Therapy can actually be the most effective form of torture.
The article talks about an experiment performed on dogs in the 1960s:
"Martin Seligman developed the learned helplessness model by performing experiments in which dogs were exposed to the trauma of being electrically shocked. Some dogs were pre-conditioned by being given painful electrical shocks in a cage in which the exit gate was blocked. Later these same dogs failed to escape the shocks by escaping through an unlocked gate. They had learned helplessness from their previous traumatic experiences and would not take the initiative required to escape being traumatized again. This was interpreted as a kind of negative operant conditioning, learning how not to learn and inducing helplessness to the point of blocking further inquiry about the traumatizing environment. These humanized animals (dogs were used not rats) were not only rendered helpless, they were unavoidably terrorized and forced to suffered the awareness of impending pain without being able to understand any reason for it."
The most effective form of torture isn't physical. More accurately, it's not PURELY physical.
Through pain (one of the most primitive teaching tools), the dogs learned that they were unable to escape their prison. Even when the door was unlocked, they knew they were going to be hurt, so they didn't try to escape.
The article took it a step further by saying, "if traumatized detainees, like the dogs of Seligman’s early experiments, learn that they are helpless and they will transfer all power in the interrogation transaction to the interrogator, and do anything the interrogator demands. In order for this to work, the prisoner has to be thoroughly convinced that their situation is inescapable and under the total control of their handlers. They must not even be allowed the autonomy to basic physiological self-regulation such as eating, sleeping, elimination (deprivations that not even the experimental animals faced), and they must be deprived all forms of personal security or dignity."
Brutal, but highly effective! By conditioning people to BELIEVE they are helpless, they will have no choice but to do what their interrogator asks. It's a cruel sort of cognitive conditioning, but it's truly the most effective (albeit long-term) form of torture.