I believe studies on this are worthless. Show 2-3 modals to a user and he/she tends to understand where the positive button is & where the negative button is. I

I believe studies on this are worthless. Show 2-3 modals to a user and he/she tends to understand where the positive button is & where the negative button is. Its more about habit than of user experience. No one actually reads that many lines of text.