The 1891 patent for the toilet paper roll literally states that the end of the roll should be hanging off the exterior, in other words, it should be placed in the ‘over’ position.
Also to know is, what does the way you put toilet paper on say about you?
As Dr. Carle says, “Assertive (roll over) people are more likely to be in leadership roles and to have a take-charge attitude. Those hanging the roll ‘under’ are more likely to be submissive. Submissive people tend to be more agreeable, flexible and empathetic.”