I had no idea what the hell a rolling ball was, so I had to look it up.
Recently, the globe effect has been linked to the peculiar properties of human visual perception,[3] which adds a certain amount of barrel distortion to the visual field.[4] The amount of barrel distortion is subject to individual differences, which explains the fact that the perceived intensity of the globe effect varies significantly between different observers.
https://en.wikipedia.org/wiki/Globe_effect