Synesthesia is a perceptual phenomenon in which stimulation of one sensory or cognitive pathway leads to involuntary experiences in a second sensory or cognitive pathway. People who report a lifelong history of such experiences are known as synesthetes.Awareness of synesthetic perceptions varies from person to person. In one common form of synesthesia, known as grapheme–color synesthesia.

An approximation of Eigengrau vs. The black colorEigengrau (: 'intrinsic gray', lit.

'own gray'; pronounced ), also called Eigenlicht ( and German: 'own light'), dark light, or brain gray, is the uniform dark background that many people report seeing in the absence of. The term Eigenlicht dates back to the nineteenth century, but has rarely been used in recent scientific publications. Common scientific terms for the phenomenon include 'visual noise' or 'background adaptation'. These terms arise due to the perception of an ever-changing field of tiny black and white dots seen in the phenomenon.Eigengrau is perceived as lighter than a object in normal lighting conditions, because is more important to the visual system than absolute brightness. For example, the night sky looks darker than Eigengrau because of the contrast provided by the stars.EigengrauColor coordinates#16161DB (, )(22, 22, 29)H (, )(24, 24, 0, 89)(, )(240°, 24%, 11%)SourceBlackB: Normalized to 0–255 (byte)H: Normalized to 0–100 (hundred)Cause Researchers noticed early on that the shape of intensity-sensitivity curves could be explained by assuming that an intrinsic source of noise in the produces random events indistinguishable from those triggered by real.

Later experiments on of ( Bufo marinus) showed that the frequency of these spontaneous events is strongly temperature-dependent, which implies that they are caused by the thermal of. In human rod cells, these events occur about once every 100 seconds on average, which, taking into account the number of rhodopsin molecules in a rod cell, implies that the of a rhodopsin molecule is about 420 years. The indistinguishability of dark events from photon responses supports this explanation, because rhodopsin is at the input of the chain. On the other hand, processes such as the spontaneous release of cannot be completely ruled out. See also.References.

Ladd, Trumbull (1894). Psychological Review. 1 (4): 351–55.:. Retrieved 28 September 2012. Hansen RM, Fulton AB (January 2000).

'Background adaptation in children with a history of mild retinopathy of prematurity'. Dragon pals. 41 (1): 320–24. Wallach, Hans (1948). 'Brightness Constancy and the Nature of Achromatic Colors'.

Journal of Experimental Psychology. 38 (3): 310–24. (1972).

'Dark and Light Adaptation: Psychophysics.' Visual Psychophysics. New York: Springer-Verlag. (1977).

'Retinal and Central Factors in Human Vision Limited by Noise'. New York: Academic Press.

Baylor, D.A.; Matthews, G; Yau, K.-W. Journal of Physiology. 309: 591–621. Baylor, Denis A. (1 January 1987). Investigative Ophthalmology & Visual Science. 28 (1): 34–49.

Shapley, Robert; Enroth-Cugell, Christina (1984). 'Visual Adaptation and Retinal Gain Controls'. Progress in Retinal Research.

Eigengrau (German: 'intrinsic gray', lit. 'own gray'; pronounced [ˈʔaɪ̯gn̩ˌgʁaʊ̯]), also called Eigenlicht (Dutch and German: 'own light'), dark light, or brain gray, is the uniform dark gray background that many people report seeing in the absence of light. The term Eigenlicht dates back to the nineteenth century,^[1] but has rarely been used in recent scientific publications. Common scientific terms for the phenomenon include 'visual noise' or 'background adaptation'. These terms arise due to the perception of an ever-changing field of tiny black and white dots seen in the phenomenon.^[2]

Eigengrau is perceived as lighter than a black object in normal lighting conditions, because contrast is more important to the visual system than absolute brightness.^[3] For example, the night sky looks darker than Eigengrau because of the contrast provided by the stars.

Cause[edit]

Researchers noticed early on^[when?] that the shape of intensity-sensitivity curves could be explained by assuming that an intrinsic source of noise in the retina produces random events indistinguishable from those triggered by real photons.^[4][5] Later experiments on rod cells of cane toads (Bufo marinus) showed that the frequency of these spontaneous events is strongly temperature-dependent, which implies that they are caused by the thermal isomerization of rhodopsin.^[6] In human rod cells, these events occur about once every 100 seconds on average, which, taking into account the number of rhodopsin molecules in a rod cell, implies that the half-life of a rhodopsin molecule is about 420 years.^[7] The indistinguishability of dark events from photon responses supports this explanation, because rhodopsin is at the input of the transduction chain. On the other hand, processes such as the spontaneous release of neurotransmitters cannot be completely ruled out.^[8]

See also[edit]

References[edit]

1. ^Ladd, Trumbull (1894). 'Direct control of the retinal field'. Psychological Review. 1 (4): 351–55. doi:10.1037/h0068980. Retrieved 28 September 2012.
2. ^Hansen RM, Fulton AB (January 2000). 'Background adaptation in children with a history of mild retinopathy of prematurity'. Invest. Ophthalmol. Vis. Sci. 41 (1): 320–24. PMID10634637.
3. ^Wallach, Hans (1948). 'Brightness Constancy and the Nature of Achromatic Colors'. Journal of Experimental Psychology. 38 (3): 310–24. doi:10.1037/h0053804. PMID18865234.
4. ^Barlow, H.B. (1972). 'Dark and Light Adaptation: Psychophysics.'. Visual Psychophysics. New York: Springer-Verlag. ISBN978-0-387-05146-8.
5. ^Barlow, H.B. (1977). 'Retinal and Central Factors in Human Vision Limited by Noise'. Vertebrate Photoreception. New York: Academic Press. ISBN978-0-12-078950-4.
6. ^Baylor, D.A.; Matthews, G; Yau, K.-W. (1980). 'Two components of electrical dark noise in toad retinal rod outer segments'. Journal of Physiology. 309: 591–621. doi:10.1113/jphysiol.1980.sp013529. PMC1274605. PMID6788941.
7. ^Baylor, Denis A. (1 January 1987). 'Photoreceptor Signals and Vision'. Investigative Ophthalmology & Visual Science. 28 (1): 34–49. PMID3026986.
8. ^Shapley, Robert; Enroth-Cugell, Christina (1984). 'Visual Adaptation and Retinal Gain Controls'. Progress in Retinal Research. 3: 263–346. doi:10.1016/0278-4327(84)90011-7.