I think that people spank from two very different points of view; there are those who spank, and think it's the right way to raise a child, and there are those who spank because they simply loose it. It depends on whether one is emotionally stable or unstable when it happens. I have two children, and before I had them, I was sure that I would never lay hands on them. However, I have slapped my now 4-year old on a few occations. I'm very ashamed of it, but I some times just loose control of myself. I find that different than having a system for physical punishment - which I suppose all types could have, but raising your child according to a system, seems quite J to me. Ps are generally more easy going, right?
And, yes, I was spanked, mostly by my ISTJ-father. (My mother used to pinch me, twist my arm and things like that - no spanking.) I think my father was somewhat unstable when he spanked me - the level of frustration was just too high for him to handle. He didn't believe it was wrong, though. I think spanking is wrong, but even so, I find that I repeat his mistakes (in a much milder manner.)
I don't believe in spanking, I try to dicipline my children mainly by removing privileges when they don't behave. Turning the TV off, taking a treasured toy away, things like that. And I normally give a warning: "If you do that again, you can't have your toy for the rest of the day." "If you sit on the table again, you won't have dinner". I also lock myself in with the child - "If you hit your sister, we'll sit together in the bathroom until you regret what you have done". Things like that are much more efficient in my opinion. But when I'm really exhausted, I tend to yell a lot - and, like I said, sometimes even get a little physical. I'm not proud of it, and I believe it's because of what was done to me as a child. And I can't really blame my father either, because he just repeated what was done to him. I just wish he had the ability to see that it was wrong in retrospect.
Even now, at 32 years, he sometimes says that I wasn't spanked sufficiently as a child. That really pisses me off - I find it very disrespectful to say something like that to an adult. I'm also provoked by how him spanking me and my brother is something of a humorous family anecdote, it's not looked upon with any kind of regret or shame from my parents point of view.