Editing Color blindness (section)

==History==
[[File:US Flag color blind.png|thumb|An 1895 illustration of normal vision and various kinds of color blindness]]
During the 17th and 18th century, several philosophers hypothesized that not all individuals perceived colors in the same way:<ref>{{cite book |last1=Lanthony |first1=Philippe |title=The History of Color Blindness |date=2018 |publisher=Wayenborgh Publishing |isbn=978-90-6299-903-3 |page=3 |url=https://books.google.com/books?id=4qJ8DwAAQBAJ&pg=PA14 |access-date=14 April 2022 |archive-date=3 October 2024 |archive-url=https://web.archive.org/web/20241003080814/https://books.google.com/books?id=4qJ8DwAAQBAJ&pg=PA14#v=onepage&q&f=false |url-status=live }}</ref>
{{blockquote
|text=...there is no reason to suppose a perfect resemblance in the disposition of the Optic Nerve in all Men, since there is an infinite variety in every thing in Nature, and chiefly in those that are Material, 'tis therefore very probable that all Men see not the same Colours in the same Objects.
|author=[[Nicolas Malebranche]]
|source=''The search after truth'' (1674)
<ref>{{cite book |last1=Malebranche |first1=Nicolas |title=Malebranch's search after truth, or, A treatise of the nature of the humane mind and of its management for avoiding error in the sciences : vol I: done out of French from the last edition. |date=1712 |orig-date=1674 |page=88 |url=https://quod.lib.umich.edu/cgi/t/text/pageviewer-idx?cc=eebo2;c=eebo2;idno=a51655.0001.001;seq=121;vid=60613;page=root;view=text |access-date=14 April 2022 |language=en |archive-date=22 April 2023 |archive-url=https://web.archive.org/web/20230422014809/https://quod.lib.umich.edu/cgi/t/text/pageviewer-idx?cc=eebo2;c=eebo2;idno=a51655.0001.001;seq=121;vid=60613;page=root;view=text |url-status=live }}</ref>
}}

{{blockquote
|text=In the power of conceiving ''colors'', too, there are striking differences among individuals: and, indeed, I am inclined to suspect, that, in the greater number of instances, the supposed defects of sight in this respect ought to be ascribed rather to a defect in the power of conception.
|author=[[Dugald Stewart]]
|source=''Elements of the philosophy of the human mind'' (1792)
<ref>{{cite book |last1=Stewart |first1=Dugald |author1-link=Dugald Stewart |title=Elements of the philosophy of the human mind |date=1792 |page=80 |edition=1 |url=https://quod.lib.umich.edu/m/moa/AJE6414.0001.001/94 |access-date=14 April 2022 |archive-date=14 October 2023 |archive-url=https://web.archive.org/web/20231014090241/https://quod.lib.umich.edu/m/moa/AJE6414.0001.001/94 |url-status=live }}</ref>
}}

[[Gordon Lynn Walls]] claims<ref name="Walls56">{{cite journal |last1=Walls |first1=Gordon L. |title=The G. Palmer Story (Or, "What It's Like, Sometimes, To Be A Scientist") |journal=Journal of the History of Medicine and Allied Sciences |date=1956 |volume=11 |issue=1 |pages=66–96 |doi=10.1093/jhmas/XI.1.66 |jstor=24619193 |pmid=13295579 |url=https://www.jstor.org/stable/24619193 |issn=0022-5045 |access-date=29 March 2024 |archive-date=3 October 2024 |archive-url=https://archive.today/20241003083353/https://www.jstor.org/stable/24619193 |url-status=live }}</ref> that the first well-circulated case study of color blindness was published in a 1777 letter from Joseph Huddart to [[Joseph Priestley]], which described "Harris the Shoemaker" and several of his brothers with what would later be described as protanopia. There appear to be no earlier surviving historical mentions of color blindness, despite its prevalence.<ref name="Walls56"/>

The phenomenon only came to be scientifically studied in 1794, when English chemist [[John Dalton]] gave the first account of color blindness in a paper to the [[Manchester Literary and Philosophical Society]], which was published in 1798 as ''Extraordinary Facts relating to the Vision of Colours: With Observations''.{{sfn|Lanthony|2018|p=14}}<ref name="Dalton1">{{cite journal |last1=Dalton |first1=John |author1-link=John Dalton |title=Extraordinary Facts relating to the Vision of Colours: With Observations |journal=Manchester Literary and Philosophical Society |date=1798 |volume=5 |issue=1 |pages=28–45 |url=https://digital.sciencehistory.org/works/fb4949523 |series=Memoirs |location=England, Manchester |access-date=14 April 2022 |archive-date=28 March 2023 |archive-url=https://web.archive.org/web/20230328081022/https://digital.sciencehistory.org/works/fb4949523 |url-status=live }}</ref> Genetic analysis of Dalton's preserved eyeball confirmed him as having deuteranopia in 1995, some 150 years after his death.<ref>{{cite journal |last1=Hunt|first1=D. M. |last2=Dulai |first2=K. S. |last3=Bowmaker |first3=J. K. |last4=Mollon |first4=J. D. |date=February 17, 1995 |title=The chemistry of John Dalton's color blindness |journal=Science |volume=267 |issue=5200 |pages=984–988 |doi=10.1126/science.7863342|pmid=7863342 |bibcode=1995Sci...267..984H |s2cid=6764146 }}</ref>

Influenced by Dalton, German writer [[J. W. von Goethe]] studied color vision abnormalities in 1798 by asking two young subjects to match pairs of colors.{{sfn|Lanthony|2018|pp=25–26}}

In 1837, [[August Seebeck]] first discriminated between protans and deutans (then as class I + II).<ref>{{cite journal |last1=Seebeck |first1=August |title=Über den bei mancher Personen vorkommenden Mangel an Farbensinn |journal=Annalen der Physik |date=1837 |page=42}}</ref><ref name="Walls56"/> He was also the first to develop an objective test method, where subjects sorted colored sheets of paper, and was the first to describe a female colorblind subject.<ref>{{cite journal |last1=Lee |first1=BB |title=The evolution of concepts of color vision. |journal=Neurociencias |date=1 July 2008 |volume=4 |issue=4 |pages=209–224 |pmid=21593994|pmc=3095437 }}</ref>

In 1875, the [[Lagerlunda rail accident|Lagerlunda train crash]] in Sweden brought color blindness to the forefront. Following the crash, Professor [[Alarik Frithiof Holmgren]], a physiologist, investigated and concluded that the color blindness of the engineer (who had died) had caused the crash. Professor Holmgren then created the first test for color vision using multicolored skeins of wool to detect color blindness and thereby exclude the color blind from jobs in the transportation industry [[#Signal lights|requiring color vision to interpret safety signals]].<ref name=VC86>{{cite journal | vauthors = Vingrys AJ, Cole BL | title = Origins of colour vision standards within the transport industry | journal = Ophthalmic & Physiological Optics | volume = 6 | issue = 4 | pages = 369–75 | year = 1986 | pmid = 3306566 | doi = 10.1111/j.1475-1313.1986.tb01155.x | s2cid = 41486427 }}</ref> However, there is a claim that there is no firm evidence that color deficiency did cause the collision, or that it might have not been the sole cause.<ref name=lagerlunda>{{cite journal | vauthors = Mollon JD, Cavonius LR | title = The Lagerlunda collision and the introduction of color vision testing | journal = Survey of Ophthalmology | volume = 57 | issue = 2 | pages = 178–94 | year = 2012 | pmid = 22301271 | doi = 10.1016/j.survophthal.2011.10.003 }}</ref>

In 1920, Frederick William Edridge-Green devised an alternative theory of color vision and color blindness based on Newton's classification of 7 fundamental colors ([[ROYGBIV]]). Edridge-Green classified color vision based on how many distinct colors a subject could see in the spectrum. Normal subjects were termed ''hexachromic'' as they could not discern Indigo. Subjects with superior color vision, who could discern indigo, were ''heptachromic''. The color blind were therefore ''dichromic'' (equivalent to dichromacy) or ''tri-'', ''tetra-'' or ''pentachromic'' (anomalous trichromacy).<ref>{{cite journal |last1=McLaren |first1=K. |title=Newton's indigo |journal=Color Research & Application |date=1985 |volume=10 |issue=4 |pages=225–229 |doi=10.1002/col.5080100411}}</ref><ref>{{cite journal |last1=Edridge-Green |first1=F. W. |title=Trichromic Vision and Anomalous Trichromatism |journal=Proceedings of the Royal Society of London. Series B, Containing Papers of a Biological Character |date=1913 |volume=86 |issue=586 |pages=164–170 |doi=10.1098/rspb.1913.0010 |jstor=80517 |s2cid=129045064 |url=https://www.jstor.org/stable/80517 |issn=0950-1193 |access-date=26 September 2022 |archive-date=26 September 2022 |archive-url=https://web.archive.org/web/20220926081103/https://www.jstor.org/stable/80517 |url-status=live }}</ref>