Tactile illusion: Difference between revisions

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{{refimprove|date=June 2016}}
{{refimprove|date=June 2016}}
'''Tactile illusions''' are [[illusion]]s that exploit the [[sense]] of [[tactition|touch]]. Some touch illusions require active touch (e.g., movement of the fingers or hands), whereas others can be evoked passively (e.g., with external stimuli that press against the skin).
'''Tactile illusions''' are [[illusion]]s that affect the [[sense]] of [[tactition|touch]]. Some tactile illusions require active touch (e.g., movement of the fingers or hands), whereas others can be evoked passively (e.g., with external stimuli that press against the skin). In recent years, a growing interest among perceptual researchers has led to the discovery of new tactile illusions and to the celebration of tactile illusions in the popular science press.<ref>{{cite journal|title=Seven ways to fool your sense of touch|journal=New Scientist|url=https://www.newscientist.com/article/mg20126997-200-seven-ways-to-fool-your-sense-of-touch/}}</ref>


==Examples==
==Examples==
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*The [[tau effect]] is an illusion in which equally spaced taps to the skin are perceived as unequally spaced, depending on the timing between the taps.
*The [[tau effect]] is an illusion in which equally spaced taps to the skin are perceived as unequally spaced, depending on the timing between the taps.
*The [[kappa effect]] is a complementary illusion to the tau effect: taps separated by equal temporal intervals are perceived to be separated by unequal temporal interval, depending on the spatial intervals between the taps.
*The [[kappa effect]] is a complementary illusion to the tau effect: taps separated by equal temporal intervals are perceived to be separated by unequal temporal interval, depending on the spatial intervals between the taps.
*Focal adaptation evoked by prolonged stimulation to a skin area causes the illusion that two stimulus points straddling that area are farther apart than they actually are.<ref>{{cite journal|last1=Li|first1=Lux|last2=Chan|first2=Arielle|last3=Iqbal|first3=Shah M.|last4=Goldreich|first4=Daniel|title=An Adaptation-Induced Repulsion Illusion in Tactile Spatial Perception|journal=Frontiers in Human Neuroscience|date=28 June 2017|volume=11|doi=10.3389/fnhum.2017.00331|url=http://journal.frontiersin.org/article/10.3389/fnhum.2017.00331/full}}</ref> This perceptual repulsion illusion is analogous to various visual repulsion illusions such as [[visual tilt effects]].
*If a person exposes their forearm and closes their eyes or turns their head in the opposite direction while a second person slowly traces a finger from the wrist upward to the crook of the elbow, many people are unable to say when the crease of their elbow is being touched.
*If a person exposes their forearm and closes their eyes or turns their head in the opposite direction while a second person slowly traces a finger from the wrist upward to the crook of the elbow, many people are unable to say when the crease of their elbow is being touched.<ref>{{cite journal|last1=Brugger|first1=Peter|last2=Meier|first2=Rebekka|title=A New Illusion at Your Elbow|journal=Perception|date=January 2015|volume=44|issue=2|pages=219–221|doi=10.1068/p7910}}</ref>
*When eating, if a person holds food with one texture and another texture is presented to the mouth, many people perceive the perceived freshness and crispiness of the food to be between the two textures.<ref>{{cite web | url=https://2c39774a-a-62cb3a1a-s-sites.googlegroups.com/site/mbarnettcowan/publications/Barnett-Cowan%282010%29Anillusionyoucansinkyourteethinto.pdf?attachauth=ANoY7cpe2gHqCdANfD9pIDdUMtca8PtQ4Ym3s2OlO2GGoDatSqR_gk2zmNC-1zJLkX_3AZOS0vgwyRPnOKo7gEwbgAciYOoNcyPrtgXBCKJjF6utuJALej9fH2KbOLxnLUJm1kg8NrtarwrctCJ_QUSTjWc11sZ7N05-3-j3MRovMwqWCqAkgWRsz9v1uOVpGtRImygDLaZJ2tSXqoNiIQ9AQTYPt-J82sf3Y9NsZQEbRiBrqCqk-ZcsL1vEgfZeUAf8orwF9G28_cSuNThwIxplxIrBOqFdIUyFz_ojbhQZWdO4UvTeKAg%3D&attredirects=0 | title=An illusion you can sink your teeth into: Haptic cues modulate the perceived freshness and crispness of pretzels | accessdate=November 15, 2012 | author=Michael Barnett-Cowan}}</ref>
*When eating, if a person holds food with one texture and another texture is presented to the mouth, many people perceive the perceived freshness and crispiness of the food to be between the two textures.<ref>{{cite web | url=https://2c39774a-a-62cb3a1a-s-sites.googlegroups.com/site/mbarnettcowan/publications/Barnett-Cowan%282010%29Anillusionyoucansinkyourteethinto.pdf?attachauth=ANoY7cpe2gHqCdANfD9pIDdUMtca8PtQ4Ym3s2OlO2GGoDatSqR_gk2zmNC-1zJLkX_3AZOS0vgwyRPnOKo7gEwbgAciYOoNcyPrtgXBCKJjF6utuJALej9fH2KbOLxnLUJm1kg8NrtarwrctCJ_QUSTjWc11sZ7N05-3-j3MRovMwqWCqAkgWRsz9v1uOVpGtRImygDLaZJ2tSXqoNiIQ9AQTYPt-J82sf3Y9NsZQEbRiBrqCqk-ZcsL1vEgfZeUAf8orwF9G28_cSuNThwIxplxIrBOqFdIUyFz_ojbhQZWdO4UvTeKAg%3D&attredirects=0 | title=An illusion you can sink your teeth into: Haptic cues modulate the perceived freshness and crispness of pretzels | accessdate=November 15, 2012 | author=Michael Barnett-Cowan}}</ref>
*If one hand is immersed in cold water and the other in hot for a minute or so, and then both hands are placed in lukewarm water, the lukewarm water will feel hot to the hand previously immersed in cold water, and cold to the hand previously immersed in hot water.
*If one hand is immersed in cold water and the other in hot for a minute or so, and then both hands are placed in lukewarm water, the lukewarm water will feel hot to the hand previously immersed in cold water, and cold to the hand previously immersed in hot water.

Revision as of 15:46, 1 July 2017

Tactile illusions are illusions that affect the sense of touch. Some tactile illusions require active touch (e.g., movement of the fingers or hands), whereas others can be evoked passively (e.g., with external stimuli that press against the skin). In recent years, a growing interest among perceptual researchers has led to the discovery of new tactile illusions and to the celebration of tactile illusions in the popular science press.[1]

Examples

  • One of the best known passive tactile illusions is the cutaneous rabbit illusion, in which a sequence of taps at two separated skin locations results in the perception that intervening skin regions were also tapped.[2]
  • The tau effect is an illusion in which equally spaced taps to the skin are perceived as unequally spaced, depending on the timing between the taps.
  • The kappa effect is a complementary illusion to the tau effect: taps separated by equal temporal intervals are perceived to be separated by unequal temporal interval, depending on the spatial intervals between the taps.
  • Focal adaptation evoked by prolonged stimulation to a skin area causes the illusion that two stimulus points straddling that area are farther apart than they actually are.[3] This perceptual repulsion illusion is analogous to various visual repulsion illusions such as visual tilt effects.
  • If a person exposes their forearm and closes their eyes or turns their head in the opposite direction while a second person slowly traces a finger from the wrist upward to the crook of the elbow, many people are unable to say when the crease of their elbow is being touched.[4]
  • When eating, if a person holds food with one texture and another texture is presented to the mouth, many people perceive the perceived freshness and crispiness of the food to be between the two textures.[5]
  • If one hand is immersed in cold water and the other in hot for a minute or so, and then both hands are placed in lukewarm water, the lukewarm water will feel hot to the hand previously immersed in cold water, and cold to the hand previously immersed in hot water.
  • An example of an active 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 the crossed index and middle finger along an edge evokes the perception of two parallel edges. Similarly, if a person crosses their index and middle finger and then rolls a marble between the tips of the fingers, two marbles are perceived.
  • 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 turns their tongue upside down, and runs their finger along the front, it will feel like the finger is moving in the opposite direction.
  • If a person pushes outwards with their hands against something for a while, then stops, it will feel as if there is something stopping the person's hands from closing together. Similarly, if a person pulls outwards with their arms, for example pulling their pants outwards, then stops, it will feel as if something is keeping their hands from staying at their sides.
  • If a person is lying on their stomach with arms stretched in front and another person raises their arms about 2 feet off the ground and holds them there for approximately one minute, with the person on the ground having their eyes closed and head hanging, then slowly lowers the arms to the ground, it will feel as if the arms are going below the level of the rest of the body.
  • When touching paradoxical objects,[6] you can feel a hole when actually you are touching a bump.[7] These "illusory" objects can be used to create tactile "virtual objects".[8]
  • After exercising on a treadmill or walking on a moving sidewalk for extended periods, a person will often feel 'pulled forward' when they step off onto stationary ground.
  • If two people join their opposite hands and one slides his index and thumb over two joined fingers he will feel the other finger like it was one of his.
  • If a person has been in the sea for a long time, they may afterwards still feel the ocean current pushing and pulling them.

References

  1. ^ "Seven ways to fool your sense of touch". New Scientist.
  2. ^ Geldard, F. A.; Sherrick, C. E. (13 October 1972). "The Cutaneous "Rabbit": A Perceptual Illusion". Science. 178 (4057): 178–179. doi:10.1126/science.178.4057.178. PMID 5076909.
  3. ^ Li, Lux; Chan, Arielle; Iqbal, Shah M.; Goldreich, Daniel (28 June 2017). "An Adaptation-Induced Repulsion Illusion in Tactile Spatial Perception". Frontiers in Human Neuroscience. 11. doi:10.3389/fnhum.2017.00331.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  4. ^ Brugger, Peter; Meier, Rebekka (January 2015). "A New Illusion at Your Elbow". Perception. 44 (2): 219–221. doi:10.1068/p7910.
  5. ^ Michael Barnett-Cowan. "An illusion you can sink your teeth into: Haptic cues modulate the perceived freshness and crispness of pretzels" (PDF). Retrieved November 15, 2012.
  6. ^ Gabriel Robles-De-La-Torre. "Haptic Perception of Shape: touch illusions, forces and the geometry of objects". Retrieved November 15, 2012.
  7. ^ Robles-De-La-Torre G.; Hayward V. (2001). "Force Can Overcome Object Geometry In the perception of Shape Through Active Touch" (PDF). Nature. 412 (6845): 445–8. doi:10.1038/35086588. PMID 11473320. {{cite journal}}: Unknown parameter |lastauthoramp= ignored (|name-list-style= suggested) (help)
  8. ^ Duncan Graham-Rowe. "The Cutting Edge of Haptics". Retrieved November 15, 2012.

Further reading