I think there are some studies that show modafinil leads to a boost in IQ by a couple of points (although it sounds like that effect tapers off if you're alread

I think there are some studies that show modafinil leads to a boost in IQ by a couple of points (although it sounds like that effect tapers off if you're already very intelligent). What makes you say the effect on the brain of modafinil is "on a different scale" than caffeine?