Pinocchio illusion

The Pinocchio illusion is an illusion that ones nose is growing longer, as happened to the literary character, Pinocchio when he told a lie. It is an illusion of proprioception, reviewed by Lackner (1988).

To experience the illusion, a vibrator is applied to the biceps tendon while one holds one's nose with the hand of that arm. The vibrator stimulates muscle spindles in the biceps that would normally be stimulated by the muscle's stretching, creating a kinesthetic illusion that the arm is moving away from the face. Because the fingers holding the nose are still giving tactile information of being in contact with the nose, it appears that the nose is moving away from the face too, in a form of perceptual capture.

The illusion involves activity in the parietal cortex of the brain responsible for integrating information from different parts of the body (e.g, Ehrsson, Kito, Sadato, Passingham, & Naito, 2005). Distortions of the size of parts of the body can sometimes occur spontaneously or during epilepsy or migraine auras.

References

* Ehrsson, H. H., Kito, T., Sadato, N., Passingham, R. E., & Naito, E. (2005). Neural substrate of body size: Illusory feeling of shrinking of the waist. "PLoS Biology, 3"(12).
* Lackner, J. R. (1988). Some proprioceptive influences on the perceptual representation of body shape and orientation. "Brain, 111," 281-297.

ee also

* Body image