Dermo-optical perception

Dermo-optical perception (DOP)—also known as dermal vision, dermo-optics, eyeless sight, eyeless vision, skin vision, skin reading, finger vision, paroptic vision, para-optic perception, cutaneous perception, digital sight, and bio-introscopy^[1]—are terms that are used in parapsychological literature to denote the alleged capability to perceive colors, differences in brightness, and/or formed images through the skin (without using the eyes, as distinct from blindsight), especially upon touching with the fingertips.

Typically, people who claim to have dermo-optical perception claim to be able to see using the skin of their fingers or hands. People who claim to have DOP often demonstrate it by reading while blindfolded.

The effect has not still been proven scientifically.^[2]

Scientific assessment

The first Western scientific reports are from the 17th century.^[3] Scattered cases kept being reported over the years, but scientific interest didn't pick up until the 20th century.^[3] ESP researchers enthusiastically studied DOP, hoping that it was an example of extra-sensory perception, but they could only conclude that some of the results couldn't be explained by cheating.^[3]

Life magazine reported on several cases on June 12, 1964, and on April 19, 1937, calling them "X-ray wonders", but all of them were found to be cheating when tested under controlled conditions.^[4]

Studies done by Western scientists showed no effect, while studies done by Eastern scientists always showed this effect.^[2] The positive results have not been accepted because their procedures were probably not tight enough to prevent cheating by participants; also, the lack of proper documentation doesn't allow to check if the controls were really good enough.^[2] There are also problems with replicating the effect reliably,^[2] and concerns about the colors being recognized by the texture of the ink on the paper (people who are blind from an early age can recognize Braille patters that only have .2 millimeters of elevation above the paper, and the limit of relief distinction in fingers is still unknown).^[2] In summary, DOP is not still proven scientifically.^[2]

Most of DOP positive results have been explained as cheating by participants, either via the use of magicians' tricks,^[5] or via "peeking down the nose" (cheating by participants)^[2][3] However, some of the results can't be explained by cheating.^[3] In recent years, DOP has been the object of "mainstream" research that had no links with ESP.^[3]

Apart from the "cheating" explanation, there are several hypothesis about how fingers could "see" radiation emitted by the colors in the paper, but none has been tested successfully.^[2] For example, people can hold their fingers near to painted and non-painted surfaces, and distinguish them by how much corporal heath is radiated back to their fingers.^[3] It has not been verified if fingers can be sensitive enough to detect heat radiation from different inks in paper, and it's theorized that blind people could plausibly do it.^[3]

The low quality of many studies, the cheating, the discovery that the most famous cases were just frauds, the use by ESP proponents, and the similarity to the tricks used by Chinese Qigong masters^[6] have caused DOP to be classified as pseudoscience and to be dismissed as baseless paranormal claims. However, there are indications that DOP is a real effect and that it can be explained by mainstream science, and there is still serious research about how it works.

References

1. ^ Blom, Jan Dirk (2009). A Dictionary of Hallucinations. Springer. pp. 553. ISBN 1441912223. http://books.google.com/books?id=qbF44AEMGdcC&lpg=PR2&hl=ru&pg=PA184#v=onepage&q=&f=true. Retrieved 2010-03-19. 
2. ^ ^{a b c d e f g h} Shiah & Tam (2005). Do Human Fingers “See”? —“Finger-Reading” Studies in the East and West. European Journal of Parapsychology, 20(2), 117–134
3. ^ ^{a b c d e f g h} Brugger, P., Weiss, P.H. (2008). Dermo-optical perception: the non-synesthetic "palpability of colors". A coment on Larner (2006). Journal of the History of the Neurosciences 17(2), 253-255,
4. ^ Joe Nickell (2007), Adventures in Paranormal Investigation (illustrated ed.), University Press of Kentucky, p. 213, ISBN 0813124670, 9780813124674, http://books.google.es/books?id=hSmW_I8nonkC 
5. ^ Dermo-optical perception, Randi Institute
6. ^ Wallace Sampson, Barry L. Beyerstein (September / October 1996), "Traditional Medicine and Pseudoscience in China: A Report of the Second CSICOP Delegation (Part 2). Special Report", Skeptical Inquirer 20.5, http://www.csicop.org/si/show/china_conference_2/ 

Bibliography (in English, Russian, and Ukrainian)

• Познанская, Н. Б. (1936). Кожная чувствительность к инфракрасным и к видимым лучам, «Бюл. экспер. биологии и медицины», т. 2, вып. 5. (Russian)
• Познанская, Н. Б. (1938). Кожная чувствительность к видимому и инфракрасному облучению, «Физиологический журнал СССР», т. XXIV, вып. 4. (Russian)
• Леонтьев, А. Н. Проблемы развития психики. М., МГУ, 1959 (Russian)
• Список публикаций А.С. Новомейского по вопросам кожно-оптической чувствительности (Russian)
• Makous, W. (1966). Cutaneous color sensitivity: explanation and demonstration. Psychological Review 73: 280-294.
• Makous, W. (1966). Dermoptical perception. Science, 152, 1109
• Duplessis Y (1985). Dermo-optical sensitivity and perception: Its influence on human behavior. Biosocial Research 7: 76–93
• Passini, R. & Rainville, C. (1992). The dermo-optical perception of color as an information source for blind travelers. Perceptual and motor skills, 75(3 Pt 1):995-1010
• Мизрахи В.М. (1998). Психологические условия развития кожно-оптического восприятия цвета у слепых школьников (idem). Диссертационная работа канд. психол. наук. Киев (Ukrainian)
• Larner A.J. (2006). A possible account of synaesthesia dating from the seventeenth century. Journal of the History of the Neurosciences 15(3): 245-249. [Not available to be downloaded, 16 October 2011].
• Martin Gardner (11 February 1966). "Dermo-optical Perception: A Peek Down the Nose". Science 151 (3711): 654–657. doi:10.1126/science.151.3711.654. 

External links

• Skeptic's Dictionary entry on Dermo-optical perception