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No. 118: Jul-Aug 1998

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Tactile Ventriloquism

An eerie psychological experiment has been invented by M. Bitvinick at the University of Pittsburgh.

  1. The subject rests his or her arm and hand on a table but is prevented from seeing them by a screen.
  2. A realistic rubber arm and hand are placed next to the real arm and hand but on the other side of the screen and in full view of the subject.
  3. The experimenter strokes each hand in synchrony with small paintbrushes.

    Result: The subject thinks that the rubber hand is his or her own and belongs to his or her body.
  4. The experimenter strokes only the rubber hand.

    Result: The subject claims his or her hand has become numb.

Botvinick terms this transfer of tactile sensations "tactile ventriloquism."

(Anonymous; "There's the Rub," Discover, 19:21, June 1998.)

Comment. Not reported: (5) Only the real hand is stroked. Of course, the subject would see that the rubber hand, which is now thought to be his or her own, is not being stroked. Nevertheless, what would be the result, especially after a long session of synchronous stroking? What connection, if any, is there with phantom-limb phenomena?

From Science Frontiers #118, JUL-AUG 1998. 1998-2000 William R. Corliss