Touch illusion
Touch illusions are illusions that exploit the sense of touch.
An example of a touch illusion is the contingent after-effect. When the thumb and forefinger are slid repeatedly along the edge of a wedge, a rectangular block then handled in the same manner will feel deformed.
Moving with index and middle finger crossed along an edge feels like two parallel edges.
Another is a physiological illusion where with one hand immersed in cold water and the other in hot and then both in lukewarm, the lukewarm water will feel both hot and cold.
