Think the whole issue of smacking is complex. And much more so because recently my sister told me that my father smacking her was very traumatic, although I was also smacked and never bothered me at all.
I have rarely smacked my dd1 and not hard. I now realise that you have to be very careful because all children are diferent. Also, assuming that your parents aren't sadists, and mine weren' t (we are a close family despite my sister's feelings), you have to keep an eye on what else is going on. My mopther was hospitalized with PND after my sister and I suspect my sister was far more sensitive than I because of this early trauma. So now, having always said I didn'tthink it was a big deal to 'tap' a hand (and I basically don't if say that hand is going near a stove) I think it's difficlut to be sure how smacking will effect a child and I will try never to do it!
J