My guess is that it's similar to the plates on the upper side of the aileron towards the flap on some airplanes, such as a newer 206. These are designed to cause the aileron to float in a direction that improves lateral stability. If the airplane banks to the right, the resulting sideslip hits the plate from the side, creating a pressure differential that moves the aileron down, raising the wing. Seems that a plate in the bottom of the aileron towards the outside could produce a similar effect.