Do you prefer iOS 5’s rounded buttons while a friend prefers iOS 4’s rectangular ones? Well, as it turns out, there’s a scientific reason why you’re right and he’s just a total idiot and needs to just talk to the hand, and it all has to do with the shape of your eyeball.
As it turns out, rounded corners are more aesthetically pleasing because the brain has an easier time processing them. Your fovea — which is responsible for sharp central vision, which is required to read, drive,watch television or use your iPhone or iPad — has an easier time processing circles than squares.
That’s not all. As Gizmodo explains:
Rounded corners also point inward and focus your eyes on the content inside an object. A squared edge is the exact opposite — it focuses your eyes on the stuff outside of the object. When you look at the rectangular buttons of iOS 4, you have to work harder to shift your gaze from the outside to the inside of the button. In iOS 5, there’s little work involved. You look at the round button, your eyes focus inward and you make your selection with ease
So what seems like a small aesthetic tweak in iOS 5 will, in actuality, make Apple’s iPhone and iPad much easier to use. They’re just always thinking of everything!