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Frege's puzzles are puzzles about the semantics of proper names, although related puzzles also arise in the case of indexicals. Gottlob Frege (1848–1925) introduced the puzzle at the beginning of his article "Über Sinn und Bedeutung" ("On Sense and Reference") in 1892 in one of the most influential articles in analytic philosophy and philosophy of language.
In Holmgren's wool test, the patient is asked to match coloured skeins of yarn to the samples in the box. [6] [7] At first, the patient is asked to select from the 40 skeins, 10 skeins that best match the light green master A. [2] From the remaining 30 skeins, the patient is then asked to select the 5 skeins that best match the red master C. [2] Lastly, the patient is asked to select 5 skeins ...
Color blindness may also present itself as a symptom of degenerative diseases of the eye, such as cataract and age-related macular degeneration, and as part of the retinal damage caused by diabetes. Vitamin A deficiency may also cause color blindness. [47] Color blindness may be a side effect of prescription drug use.
Alarik Frithiof Holmgren (October 22, 1831 – August 14, 1897) was a Swedish physician, physiologist and professor at Upsala University, most noted for his research of color blindness. He was a vocal opponent of vivisection, and particularly the use of curare to immobilize subjects so they appeared peaceful while enduring great pain. [1]
Congenital red-green color blindness, the genetic condition that causes the most cases of color blindness. Dichromacy, a type of color vision possessed by most mammals; partial color blindness when in humans. Monochromacy, a lack of color vision; total color blindness when in humans. Achromatopsia, a syndrome that includes total color blindness.
Blue cone monochromacy (BCM) is an inherited eye disease that causes severe color blindness, poor visual acuity, nystagmus, hemeralopia, and photophobia due to the absence of functional red (L) and green (M) cone photoreceptor cells in the retina. BCM is a recessive X-linked disease and almost exclusively affects XY karyotypes.
While holding a military position related to his field, he was given the task of creating a color blindness test. Ishihara studied existing tests and combined elements of the Stilling test, named after the German ophthalmologist Jakob Stilling , with the concept of pseudo-isochromaticism to produce an improved, more accurate and easier to use test.
Cerebral achromatopsia is a type of color blindness caused by damage to the cerebral cortex of the brain, rather than abnormalities in the cells of the eye's retina.It is often confused with congenital achromatopsia but the underlying physiological deficits of the disorders are completely distinct.