I dont know about evidence but I found my toddler understands way more than I thought would be reasonable to expecu of him. Like for example if Im loading the dishwasher he is supposed to not touch it at all because a) its yuck and b) he supports himself on the fully open door by pressing it down further which will break when he gains enough weight. It took some time to explain it and correct his actions with a strong "no" but now I feel comfortable leaving him there for a couple seconds and know he wont touch the door.

I dont know what exactly you mean by "traditional discipline", to me that means hitting kids on the butt and that is an absolute no go. No hitting of any kind ever for any reason whatsoever. Not as punishment, not as retaliation, never ever ever ever.