Aggression in Kids

I'm back from vacation and trying to get caught up on all the blogging that I didn't get to read. One of them was the above entry about aggressive kids and tips on how to deal with them. There were great ideas, but I'd like to ask a slightly different question:

How do you deal with a kid that truly doesn't understand? Maybe this kid is the aggressee and doesn't even seem to get that what is happening to them is mean. In that case does Mom's perception that her kid is being picked on right? Or does it only count if the pickee recognizes the picking?

Or maybe it's the other way around and the kid that's showing aggressive behavior really has no clue that what they are doing is mean? How do you apply parenting strategies to a kid that has, say, the body of a 6-year-old but the developmental level of a 3-year-old? Obviously just disciplining the way you would a typical 6-year-old probably won't be right, but you can't just discipline the way you would the 3-year-old because that ignores the physical component.

What with The Biscuit only being 14-months-old, this is all hypothetical for me now, but I'm very curious about what other parents would do. Maybe your child has a playmate with developmental disabilities and you've had to deal with this issue from the other side. Please post your comments, even if you don't stumble upon this post for 5 years.