"For both eyes the combined visual field is 130–135° vertically[33][34] and 200–220° horizontally."

https://en.m.wikipedia.org/wiki/Peripheral_vision

That means that the ideal screen ratio if you want to fill up someone's field of view while they are looking in the middle at a good distance is 0.61-0.65. 9/16 is 0.56 which is that far of. 1:2 would be 0.5 which is worse. 1:1 would be 1 which is very far from the ideal.