Lateralization of brain function
Popular articles on psychology often say that each side of the brain does things that the other does not.  For example, a common mistake is the idea that the left side of the brain does all of a person's "logical thinking" (like solving math problems), while the right brain does all the "creative thinking" (like painting or drawing).  It is often said that a person who is creative is "right-brained," while a person who is more logical or "book-smart" is "left-brained."