Is there a way to stop natural 1s and 20s from happening in NWN?

So I just don't like the idea of natural 1s and 20s, so is there a way to make it so that when you roll a 1 it turns it into a 2, and if you roll 20 it turns it into a 19? Or maybe just disable the concept of natural 1s and 20s and treat them normally? So it's not an automatic success or fail.