The "Window of Comprehension" is a term coined by Prof. Dean Keith Simonton in his article
"Intelligence and personal influence in groups: Four nonlinear models"
Psychological Review, 92, 532-547 (1985c)
It was originally used to describe leadership, but has been extended to all kinds of human relationships ever since.
The basic hypothesis is that two human beings can only have a meaningful conversation if they share a window of 15 IQ points. So a person with an IQ of 140 could interact best with people in the 126..154 range (140 plus or minus 15-1).
Some authors suggested a window of 12 points, so the default in this program is the middle ground, 13.5 points. I have also added 20, in case you want to be optimistic.
Here you can go back to the calculator, but use the "back" button if you want to preserve your entries.