As someone noted above, a high wing plane will have a dihedral effect even if the wing has no dihedral at all. Picture a skid induced by rudder: pressure builds under the outside wing, which will raise it, just like dihedral does = positive roll coupling. So if you want to cancel it, use some anhedral.

Conversely, consider a low wing plane with no dihedral in the same circumstances: pressure builds on top of the outside wing, which will lower it = negative roll coupling. So if you want to cancel it, use some dihedral.

Lots of people seem to think if reducing dihedral on, say, an Astro Hog, is better, then eliminating altogether is best. But then you wind up with a plane that has negative roll coupling.

Jim