IMHO the more likely explanation for these results is that the human visual system has built in mathematical, logical capabilities actually far beyond advanced college math. These are used to identify and track objects at a very early age. It is much easier to access these abilities using pictures and icons.

Text is an additional layer of abstraction probably involving language and communication systems outside the human visual system. The text is a label or abstraction for the visually represented concepts which must be encountered and learned first.

There is a consistent pattern in learning mathematics and other technical areas that most students learn better and faster with pictures and concrete examples. Abstraction comes later.