I am of two minds on this. I will answer honestly. I would settle heavier on the "experiment" side than "torture" side, at least by my definition. I would collect certain individuals based on criteria that helped with the focus of the experiment. One set of subjects would be fairly ordinary, everyday citizens. The other set would be sociopaths, or maybe others on a spectrum of psychopathy. Most of this "torture" would be simulated or psychological. I would want to see how subjects underwent situations of extreme duress. I could mix and mingle subsets according to religious views, social position, economic status, etc. I would be interested to see what circumstance would break which set of beliefs, preconceptions, or other paradigms most simply take for granted out in the world. I'm not interested in satisfying a sadistic impulse, so the exact designs of those "tortures" are probably too many for me to list and explain without being accused of being a pompous windbag some more. (It might be too late, already, though.) The experimental situations would need to seem as real as possible, which would probably border on unethical for many. I would love to see if I could drive someone insane purely by pressure of threats and deceptions. Those are wounds you can make without fingerprints. However, that sort of malice I would save for those I find contemptable already. Again, it might be a long list. One distinction, though: for any of the sociopaths under my study would not receive the restraint I would upon those that weren't sociopaths. I use sociopath rather generally, in this case.
One particular experiment I've been keenly curious about may be one that has been done, at least somewhat. I would like to set up a prison type of system where the different inmates were in charge of their own imprisonment. Criminals in charge of other criminals. You could easily split off certain types of offenders from others, set up some with certain authorities, flip roles around, and so forth. It would be intriguing to see how the pressures of all these dynamics would run its course. I have some real belief that criminals should be put in charge of the incarceration of other criminals. Who could appeal to the humanity of their conditions when there is no humanity to appeal to?
Indulging in a more sadistic form of curiousity, I've always found the "rats in a maze" type of experiment as very interesting. Dropping certain people into a funhouse of dangerous and deadly traps, etc. You have all probably watched movies like Saw. I suppose there's a detachment available in making their peril somewhat their own fault. I am always fascinated by the interplay and power struggles in highly survivalistic situations. That's when the true tests of humanity are made.