Why Do People Overestimate the Slant of Hills?

People overestimate the slant of hills because their brains are subtly, not so suatly, trying to persuade them not to walk up hills. This fits perfectly if you think ecologically. The body is now taxed into asresources, and it's saying, now, i really don't want to walk up that hill. In order to dissuade myself, i will perceive it as steeper and more formidable.