Touch illusion

From Freepedia

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.

If a person wears a baseball cap for a long period of time and then takes it off, it may still be felt.

If a person is lying on his/her stomach with arms stretched in front and another person raises his/her arms about 2 feet off of the ground and holds them there for approximately one minute, with the person on the ground having his/her eyes closed and head hanging, then slowly lowers the arms to the ground, it will feel as if the arms are going below the ground.

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.