Joe Ga had heard semi-professional staff of P.B. Company talk about interrogation techniques—physical restraints, fatigue, lighting, sound, and inducements—these combined could rapidly destroy a person's willpower.
The pain inflicted by the soldiers was actually a low-level method because there is a limit to human suffering.
Creating pain based on each person's physiological limits could indeed be considered an art, and only those capable of such nuances could be considered doctoral experts in interrogation. Ordinary people didn't have this opportunity, nor did they have so many subjects to practice on.
Eric had come prepared with such people, clearly knowing what he should be doing...
Watching the scarred middle-aged man inject Coyote with several drugs, he quickly revived his consciousness, then calmly and gently bandaged his wounds.