Instead of the soul, the eyes may actually serve as a window into the mind: A connection may exist between pupil size and certain types of intelligence.
Of course, intelligence comes in many forms. You can acquire knowledge from reading, following the stats on your favorite sports team, or even the street smarts that may be helpful in certain cultural contexts.
Fluid intelligence, meanwhile, isn’t related to culture or learning. It is defined as one’s ability to acquire information from their surroundings on a basic level — how to process it and solve novel problems. This sort of intelligence is largely associated with multitasking and working memory.
