Colour Incomprehension

Color Blindness

Julio A. Lillo , Humberto Moreira , in Encyclopedia of Applied Psychology, 2004

three Causes of Colour Blindness

Most color blindness is genetic in origin. In this group, the alterations associated with bug in the Fifty cones (protanopia and protanomalies) or in the M cones (deuteranopia and deuteranomalies) are collectively called "daltonisms" or "red–green bug." These problems touch many more than men (5–10%) than women (<0.ix%) because they are associated with genetic alterations in recessively transmitted X chromosomes. Consequently, men will express cerise–green issues when there are anomalies in the only Ten chromosome they have. On the other hand, a women must have issues in both X chromosomes to be daltonic. With merely ane affected chromosome, they volition show a normal use of colors merely can transmit the ruddy–green disturbance to their offspring.

The most important gene in relation to the opsin characteristic of S cones is not located in sexual chromosomes; instead, it is located in the seventh pair of chromosomes. Consequently, bug associated with these cones have a similar incidence in men and women. These types of color incomprehension are transmitted dominantly, simply they impact a very small number of people (<0.05%).

Although the chromosomes associated with rod monochromatism accept not yet been identified, this type of problem is known to exist transmitted recessively. Consequently, the affected gene must be located in both chromosomes to produce trouble expression.

Lacking color vision can be acquired by any kind of agent with the chapters to disturb the normal functioning of the visual system—the result of ocular pathology, intracranial injury, the use of therapeutic drugs, aging, and and so on. Oft, colour disturbances are initial symptoms of pathologies and can exist used for early detection, indicating when therapeutic measures should begin or when they should be discontinued. Tabular array I reviews the well-nigh important differences between acquired and congenital colour deficiencies.

TABLE I. Comparison of Acquired and Congenital Color Vision Deficiencies

Acquired color vision defect Congenital color vision defect
Onset later on nascence Onset at birth
Monocular differences in the type and severity of the defect occur frequently Both eyes are equally afflicted
Color alterations are ofttimes associated with other visual bug such as depression vigil and reductions in the useful visual field The visual issues are specific to color perception; in that location are no problems with vigil (except in rod monochromatism) or visual field
The type and severity of the deficiency fluctuate The blazon and severity of the defect are the same throughout life
The type of defect might not exist easy to classify; combined or non-specific defects occur frequently The blazon of defect tin be classified precisely
Predominantly either protan or deutan Predominantly tritan
Higher incidence in males Same incidence in both sexes

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Practical Issues in WAIS-IV Administration and Scoring

Susan Engi Raiford , ... Lawrence G. Weiss , in WAIS-4 Clinical Use and Interpretation, 2010

My examinee is color blind. Is that a factor in assistants?

Individuals with colour blindness were not excluded from the standardization samples. Every effort was made to ensure that items are costless of bias confronting these individuals. Item color combinations were reviewed past experts in colour blindness. Items were additionally administered to individuals with color blindness during the early on stages of the exam development process. Acetate overlays accept been utilized so that exam developers tin can sympathize the appearance of colors to these individuals. All items were printed in grayscale to simulate their appearance to those with monochromatic color perception. All items were additionally subjected to a reckoner programme that simulates every type of color blindness, to ensure that the intensity and saturation of colors are non confused or contributing to ambiguity.

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Transforming Illness and Visual Art

T. Zausner , in Encyclopedia of Inventiveness (2nd Edition), 2011

Color Vision Deficiency and Its Influence on Fine art

I of the well-nigh common visual impairments is colour vision deficiency, also known equally color blindness. Usually an inherited condition, it affects one in ten men and one in two hundred women. The caste of damage can range from a slight inability to see colors to a profound lack of color discrimination. Although people with color vision deficiency have issues perceiving colour, they have an enhanced power to distinguish gradations of lite and dark forth with an astute perception of textures and patterns. Color vision deficient artists use this acuity in the gradations of lite and dark that empower their work.

I of the most famous artists in Western civilisation, Rembrandt Harmenszoon van Rijn (Dutch, 1603–69), is believed to be color vision deficient. A. Hyatt Mayor, a curator at the Metropolitan Museum of Art, who was the first to recognize this in Rembrandt's work, also noted that Rembrandt's difficulty in perceiving colors gave him an increased sensitivity to tones of light and dark (see Figure 2 ). He said of Rembrandt that "seeing the earth more than or less in browns freed him to calibrate luminosity with a delicacy as expressive equally whatever palette of colors." Color vision deficiency also helped Rembrandt with his etchings, which was a black and white medium in the seventeenth century.

Figure two. Rembrandt Harmensz van Rijn (1606–69) Belshazzar's Feast, about 1636–8. Oil on canvas, 167.vi x 209.two cm. Bought with a contribution from The Fine art Fund, 1964. (NG6350). Location: National Gallery, London, Keen Britain. Photograph Credit: © National Gallery, London/Fine art Resources, NY

Image Reference: ART373904.

Although it is unusual to observe a female artist with color vision deficiency, Kaethe Kollwitz (High german, 1867–1945) appeared to accept this condition. Kollwitz, who showed talent at an early on age and wanted to be a painter, realized in art school that her color perception was flawed. She said, "In the painting class I made no progress. Color was my stumbling block." In response, Kollwitz stopped making oil paintings and focused on black and white or dark-brown and white imagery in etchings, drawings, and lithographs. She besides turned to sculpture, some other medium without colour in which she could excel. Paul Manship (American, 1885–1966) besides had color vision deficiency and changed to sculpture after difficulties with color in his paintings. Charles Meryon (French, 1821–68) was another artist with color vision deficiency who stopped painting and achieved success with his black and white etchings.

Lack of color in an artist's work cannot be used as the sole criteria to assess a person's level of color vision. Odilon Redon and Chuck Close worked nigh exclusively in black and white for the first half of their careers earlier going on to become major colorists. Caravaggio (Italian, 1573–1610), born Michelangelo Merisi, showed an excellent sense of color in his early on work just preferred a reduced palette emphasizing light and night in his later paintings.

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Critical Race Theory

D. Gillborn , G. Ladson-Billings , in International Encyclopedia of Pedagogy (Third Edition), 2010

A Critique of Liberalism

Another distinctive theme is CRT'south critique of liberalism. CRT portrays ascendant legal claims of neutrality, objectivity, color-incomprehension, and meritocracy every bit camouflages for the self-interest of powerful entities of order (Tate, 1997: 235). In the pedagogy system, for example, racism is figured in the distribution of cloth and educational resource and even in teachers' notions of ability and motivation (Gillborn, 2008). In this situation, the adoption of color-blind approaches (which refuse to acknowledge racial reality) and an emphasis on supposed merit (as measured by ascendant assessments) may appear open and equitable, but the playing field is not level. Minoritized students are more than likely to attend poorly funded schools, with less-highly qualified teachers and, because of socioeconomic inequalities, they are less probable to savor additional educational resource at home, such every bit Net access (Ladson-Billings, 2006). Nether such unequal weather, a color-blind insistence on a simple merit standard volition not only ensure that race inequalities continue but besides nowadays them as off-white and but.

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Equality and Inequality: Legal Aspects

S. Sturm , in International Encyclopedia of the Social & Behavioral Sciences, 2001

ane.1 Critiques of Formal Equality

The dominance of formal equality in American antidiscrimination law has produced a broad array of criticism. One fix of critiques questions the color-blindness prohibition on grounds of autonomy and freedom of association, a view expressed by Richard Epstein (1992). Other criticism proceeds from the view that colorblindness is an inadequate response to continuing inequality. Nigh fundamentally, critics point out that a formal equality theory leaves in tact a legacy of state-produced inequality and subordination. It ignores the role that group status continues to play in shaping the life expectancies, opportunities, and experiences of group members. It locks in the connected furnishings of past formal exclusion, imposing the consequences of that continued exclusion on the excluded groups themselves. Past defining equality solely in terms of the conduct of the perpetrator, a formal equality arroyo normalizes conditions of marginalization and exclusion, and the group dimensions of these material conditions. It does non begin to address the perspective of those who feel exclusion, marginalization, and diff enjoyment of resource and condition (Freeman 1990, Crenshaw 1988, Gotanda 1991). At the same time, 'It conceals the distributive consequences of grouping-salient practices in a semantic code that defines instrumental rationality as race-neutral' (Siegel 2000). A moral theory that might be suitable for a simply social club, i.e., one that does non systematically disadvantage people based on their race, loses its moral premise for a society that is unjust in those ways (Gutmann, 1996, Sunstein 1994).

On a conceptual level, David Strauss has pointed out the logical inconsistencies of colorblindness as an antidiscrimination principle. To protect a designated group against treatment targeting that group, the country must pay attending to and indeed specially protect the interest of that group. Thus, colorblindness is contradictory. Strauss also points out that the metaphor of colorblindness really doesn't fit its apply in the nondiscrimination context. Colorblindness in the literal sense prevents an individual from seeing color; colorblindness equally an equality model prevents an private from interim on what he or she sees. This arroyo presumes that individuals can see race but keep information technology from influencing their perceptions, behave, and decisions (Strauss 1986).

Recent work in the social sciences challenges the assumption (which underlies the formal equality model) that conscious determination making adequately describes the current dynamics of exclusion and unequal handling. Bias is produced not only equally a result of motivation but also as a product of racial or gender schemata, multiracial group interactions, and patterns of conflict resolution or abstention (Krieger 1995, Lawrence 1987, Sturm 1998). Bias or exclusion frequently results from interactive patterns of non-inclusion, as much every bit from exclusion motivated by bias (Donnelon and Kolb 1994, Wilkins and Gulati 1996). Members of nondominant groups may well exist treated differently based on their race, notwithstanding the decision maker's lack of intention to practise so.

Historians have too challenged the theory of formal equality for its ahistoricism. Colorblindness ignores historically constituted patterns of grouping inequalities that are 'socially pervasive (articulated beyond social domains), and socially persistent (articulated over time)' (Siegel 2000). Examining race and gender inequality from a historical standpoint reveals relations of group inequality embedded in the social organization of piece of work, reproduction, and sexuality. 'In short, when considered from a historical standpoint, discrimination has no transcontextual or fixed form' (Siegel 2000).

Robert Post applies this structural business relationship of the dynamics of bias to the law itself. Using what he calls a sociological account of the field, he contends that constabulary does not and cannot crusade employers to make judgments virtually qualifications in a way that is totally race and sexual activity blind. Legal actors are themselves engaged in a social practise of shaping the norms and conventions past which sexual activity and race are given social meaning. 'Antidiscrimination laws always begins and ends in history, which means that it must participate in the very practices that its seeks to alter and regulate' (Mail 2000). To pretend otherwise is to permit courts to rely on unarticulated assumptions and premises that legitimate some racial or gender meanings and challenge others.

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Equality and Inequality: Legal Aspects

Susan Sturm , in International Encyclopedia of the Social & Behavioral Sciences (Second Edition), 2015

Formal Inequality of Treatment

The baseline conception of inequality in the United states and Eu antidiscrimination constabulary is embodied in principle of equal treatment. The law pursues equality by eliminating race, gender, or other suspect social categories equally a legitimate footing of classifying people for the purpose of allocating resources or making decisions (Collins, 2003). Sometimes called the anticlassification principle (Fiss, 1971; Siegel, 2004), formal equality focuses on the country of mind of the decision maker; it targets intentional reliance on race, gender, or some other protected category as the violation of the equality norm. It is process oriented, in the sense that it regards the taking business relationship of a person's identity in the treatment of students, voters, employees, prospective homeowners, and people more generally, as both the harm and the wrongful bear.

The hallmark narrative of formal equality has as its protagonist individuals who deliberately exclude or marginalize other individuals based on their race, gender, sexual orientation, or other protected nomenclature. This model defines the wrongful conduct equally intentional, unequal handling based on race, gender, sexual orientation, historic period, or some other class-based characteristic that is viewed equally arbitrary. For inequality to count as legally relevant under this theory, information technology must be demonstrably caused by this course of deliberate, class-based exclusion.

The premise of this model is that race, gender, and other grade characteristics are irrelevant to the underlying decision, and that taking course membership into business relationship is thus capricious and unfair (Fiss, 1971; Fallon, 1984). The goal of the formal equality model is 'color incomprehension': decisions affecting people'south status and opportunity should be made without regard to social categories such equally race or gender. Race, gender, and other categories of status operate as fixed, universal, and static categories based on membership in a set, unchanging group identified past predetermined, and oft physical, characteristics such as pare color or sex. The supposition is that group status is, by definition, irrelevant to decisions based on merit, that considering class status is by nature arbitrary, denigrating, and unfair, that decision makers tin can make decisions without noticing or taking account of racial and gender characteristics, and that equality tin be achieved by a rule that prohibits decision makers from considering race or gender.

The formal equality norm rests on a principle of the dignity of the private. For those who subscribe to formal equality as an umbrella conception, 'stigma' is the crucial element in analyzing racial classifications. As the US Supreme Court recently stated, "To be forced to live under a state-mandated racial label is inconsistent with the dignity of individuals in our society" (Parents Involved in Customs Schools five. Seattle School Commune No. one, 127 S. Ct. 2738 (2007)). The Supreme Court recently extended its business concern with preserving private dignity and avoiding stigmatization to the context of sexual orientation, invalidating as inconsistent with equality principles a law that "places aforementioned-sex couples in an unstable position of existence in a second-tier marriage. The differentiation demeans the couple . . . and it humiliates tens of thousands of children now beingness raised by aforementioned-sexual practice couples" (The states v. Windsor, 133 Southward. Ct. 2675 (2013)). Canadian, French, and the EU law similarly bases prohibitions confronting disparate treatment on dignitary values, frequently drawing directly from Usa antidiscrimination laws of the 1970s (De Burca, 2012; Moreau, 2010). For example, the European Convention for the Protection of Human Rights and Fundamental Freedoms prohibits discrimination "on any ground such equally sex, race, colour, linguistic communication, religion, political or other opinion, national or social origin, association with a national minority, property, nascence or other status," and grounds this equal treatment mandate in the "independent value of respect for individual dignity" (Collins, 2003; Tremblay, 2012). Proponents of formal equality besides identify racial polarization equally a business organisation underlying color blindness jurisprudence (Siegel, 2011; Yoshino, 2011): "All state-imposed classifications that rearrange burdens and benefits on the basis of race are likely to be viewed with deep resentment past the individuals burdened. The denial to innocent persons of equal rights and opportunities may outrage those and then deprived and therefore may be perceived as invidious" (Regents of the University of California v. Bakke, 438 U.Southward. 265, 294 n. 34 (opinion of J. Powell)). Formal inequality theory provides remedies to individuals who have been subjected to a process tainted by racial or gender considerations. It is incomparably ahistorical and individualistic in its focus, and compensatory in its explicit remedial approach. Subscribers to formal equality view race and gender as biological or immutable categories that also operate every bit "a fixed yet radically empty feature[south] of every person's identity" (Siegel, 2000: p. 91). According to this view of race, in item, the category has no socially relevant content (Siegel, 2000).

Many who comprehend a formal equality arroyo believe current racial inequality results from factors unrelated to racial or gender discrimination, or at least to factors that lie beyond the constitutionally defined boundaries of equality. The election of Barack Obama, a human of mixed Caucasian and African heritage, to the Usa presidency in 2008 has prompted some conservatives to suggest that the Usa has moved to a postcivil rights society, in which race no longer operates in a fashion that is actionable through the courts. "Post-racialism is a prepare of behavior that coalesce to posit that racial bigotry is rare and aberrant behavior equally evidenced by America's and Americans' pronounced racial progress" (Barnes et al., 2010: p. 968). One critical commentator summarized the view that the mechanisms of bigotry tin be reduced to a simple paradigm – explicitly discriminatory policies and rogue individuals: "Discrimination is over. The marketplace is bias-free. The law'southward job is to discover the aberrant thespian who only didn't get the memo" (Gertner, 2012: p. 111).

Commitment to race blindness is non limited to the U.s.a.. For instance, French constabulary insists on race neutrality and "leaves no room for the possibility of justifying racial distinctions to remedy by racial harms or to promote diversity, every bit U.Due south. police does" (Suk, 2007: p. 13). Suk traces the colour blindness norm in France in part to conceptions of equality and citizenship that regard social distinctions of any sort equally a threat to republicanism (Suk, 2007).

Formal equality embraces the idea that decision makers such as employers and educational institutions may, and usually exercise, properly differentiate amid people based on qualifications relevant to capabilities and functioning. Past taking social categories such as sex or race into account, decision makers unjustifiably depart from merit-based decision making. This violates basic notions of fairness considering people deserve to be treated 'on the merits,' based on an individualized cess of their capacities (Fallon, 1984; Gutmann, 1996; Suk, 2007). Exclusion based upon characteristics that are across the command of the affected individual are viewed as particularly morally problematic (Fiss, 1976; Brest, 1976). Decisions based on course membership thus offend dignitary values, in improver to undermining instrumental values of efficiency. Perhaps the about fierce expression of this view in the US tin can be constitute in Justice Scalia'southward concurring opinion invalidating voluntary affirmative activity in authorities contracting based upon its inconsistency with the principle of color blindness: "To pursue the concept of racial entitlement—even for the nigh admirable and beneficial of purposes—is to reinforce and preserve for time to come mischief the way of thinking that produced race slavery, race privilege, and race hatred. In the eyes of regime, we are just ane race here. It is American" (Adarand Constructors vs. Pena 115 South. Ct. 2097 [1995]).

Those who encompass formal inequality may disagree about the degree of indelible inequality, only they share skepticism about the legitimacy and efficacy of efforts to address this form of inequality by taking race into account as a factor in allocating benefits and opportunities to individuals (Rappaport, 2013; Suk, 2007; Browne, 1993; Rabkin, 1997; Sowell, 1984). Courts properly focus on remedying wrongful acts by perpetrators intending to exclude people based on their race, age, sexual practice, or sexual orientation. Efforts to remedy inequality by making race a basis for private advancement are deeply suspect nether this approach. Justice Roberts restates his commitment to the color incomprehension principle in the context of higher education admissions: "The style to stop discrimination on the basis of race is to finish discriminating on the basis of race" (Parents Involved in Customs Schools v. Seattle School District No. 1, 30). Formal equality principles increasingly operate to claiming the legality of efforts to remedy enduring inequality, especially, in the context of affirmative action, voting rights, school desegregation, and other voluntary state efforts to reduce persistent, grouping-based inequality. (run across Affirmative Action: Comparative Policies and Controversies; Affirmative Action: Empirical Work on Its Effectiveness).

Critiques of Formal Equality

The dominance of formal equality in American antidiscrimination law has produced a wide array of criticism. The most prevalent concern gain from the observation that colour incomprehension is an inadequate response to standing inequality. Most fundamentally, critics betoken out that a formal equality theory leaves intact a legacy of land-produced inequality and subordination. Information technology ignores the office that group condition continues to play in shaping the life chances, opportunities, and experiences of grouping members. It locks in the connected effects of by formal exclusion, imposing the consequences of that connected exclusion on the excluded groups themselves. By defining equality solely in terms of the conduct of the perpetrator, a formal equality approach normalizes weather of marginalization and exclusion and the grouping dimensions of these cloth conditions. It does not begin to address the perspective of those who experience exclusion, marginalization, and unequal enjoyment of resource and status (Crenshaw, 1988; De Burca, 2012; Gotanda, 1991; powell, 2009). At the same time, "It conceals the distributive consequences of group-salient practices in a semantic lawmaking that defines instrumentally rational utterances as race-neutral" (Siegel, 2000: p. 101). "Acceding to a worldview on which racial inequity is primarily the production of nowadays bad actors rather than largely a matter of historically embedded hierarchies fosters the misdescription of a primal social problem and therefore helps go far less likely that the trouble volition be addressed through appropriate means" (Primus, 2003: p. 499).

On a conceptual level, David Strauss has pointed out the logical inconsistencies of color blindness as an antidiscrimination principle. To protect a designated group against treatment targeting that group, the state must pay attention to and indeed particularly protect the involvement of that group. Thus, color blindness is contradictory. Strauss also points out that the metaphor of color blindness really does not fit its apply in the nondiscrimination context. Colour incomprehension in the literal sense prevents an individual from seeing color; color blindness every bit an equality model prevents an individual from acting on what he or she sees. This approach presumes (incorrectly) that individuals tin meet race but keep information technology from influencing their perceptions, deport, and decisions (Strauss, 1986).

Recent work in the social sciences challenges the supposition that witting conclusion making fairly describes the current dynamics of exclusion and unequal treatment. Bias is produced not only equally a issue of motivation but as well as a product of racial or gender schemata, multiracial group interactions, unequal access to networks, and patterns of conflict resolution or avoidance (Bagenstos, 2006; Dasgupta, 2004; De Burca, 2006; Krieger, 1995; Sturm, 2001). Bias or exclusion oftentimes results from interactive patterns of noninclusion, as much every bit from exclusion motivated by bias (Sharkey, 2013; Wilkins and Gulati, 1996). Members of nondominant groups may well be treated differently based on their race, all the same the determination maker's lack of intention to practice so.

Historians have as well challenged the theory of formal equality for its ahistoricism. Color blindness ignores historically constituted patterns of group inequalities that are "socially pervasive (articulated across social domains), and socially persistent (articulated over time)" (Siegel, 2000: p. 82). Examining race and gender inequality from a historical standpoint reveals relations of group inequality embedded in the social organization of work, reproduction, and sexuality (Siegel, 2000). "In actuality, the The states has been plagued with … the consistent use of racial classifications to privilege (certain groups of) whites and disadvantage nonwhites" (Harris, 2000, 2009). The focus on nomenclature itself – because it makes suspect race-witting action taken to combat racism – justifies the maintenance of existing social and political relations (Harris, 2000). Equally Kenji Yoshino has noted, "an equal protection jurisprudence that turns formalistically on facial discrimination will, from an antisubordination perspective, become it exactly backward. On the i hand, this jurisprudence invalidates affirmative action programs seeking to aid historically subordinated groups. On the other hand, information technology upholds 2nd-generation discrimination that continues to subordinate those groups" (Yoshino, 2011: p. 767). Similar critiques have been made of color blindness and equal handling jurisprudence in Europe, in that location by yielding more far-reaching adoption of more proactive and structural approaches in the regulatory arena (Suk, 2007; De Burca, 2012).

Robert Mail applies this structural business relationship of the dynamics of bias to the law itself. Using what he calls a sociological account of the field, he contends that constabulary does non and cannot cause employers to make judgments about qualifications in a fashion that is totally race and sex blind. Legal actors are themselves engaged in a social do of shaping the norms and conventions by which sex and race are given social meaning. "Antidiscrimination police force always begins and ends in history, which ways that it must participate in the very practices that it seeks to alter and to regulate" (Post, 2000: p. 17). To pretend otherwise is to permit courts to rely on unarticulated assumptions and premises that legitimate some racial or gender meanings and claiming others.

A final critique relates to the threat to the court's legitimacy stemming from the gap between inequality equally recognized by police force and inequality as people experience it (Sturm, 2006b; Sturm, 2014). Every bit that gap grows, the refusal of law to acknowledge persistent inequality undermines legitimacy of the police equally an musical instrument of justice. This legitimacy deficit is compounded when the court non only defines equality narrowly only proscribes the office of other branches of government or private entities in identifying and addressing more structural dimensions of persistent inequality.

Like observations of persistent inequality left unaddressed by antidiscrimination strategies take been made in Europe. However, European and the US antidiscrimination police diverge in their response to these shared critiques of formal equality. Despite the fact that "core concepts and provisions of European union antidiscrimination law … were drawn from the United Kingdom's anti-discrimination police force of the 1970s, … [which] were in plough strongly influenced by U.South. constabulary at the time" these legal principles served every bit a predicate for dramatic expansion of European antidiscrimination laws through "new legislation and treaty provisions, new institutions such as the EU Cardinal Rights Agency, renewed ceremonious lodge activism" (De Burca, 2012: p. three). This difference has been traced to a shared European idea that "the provision and promotion of the man and social welfare of their peoples is a core aspect of the responsibility of the states" (De Burca, 2012: p. seven), in contrast with the United states legal and political civilization, which privileges the thought of individual freedom (De Burca, 2012). It is too possible that these differences stalk in part from the fact that "the United States is several decades ahead of the European Union" in the evolution of its antidiscrimination law and policy and then that "Europe has not withal experienced the powerful backfire that probably awaits an aggressive plan" (De Burca, 2012: p. ten).

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Vision: Encephalon Mechanisms

Robert Shapley , Nava Rubin , in Encyclopedia of the Human Encephalon, 2002

5 Color in Ventral Occipital Brain Areas

The idea that there is a split up localized surface area in man extrastriate cortex that is specialized for mediating color perception is derived from the phenomenon of cerebral achromatopsia (cortical color blindness). Achromatopsia is usually acquired by stroke lesions in ventral occipital–temporal cortex. Information technology is a variable clinical syndrome, with the mutual characteristic that patients cannot pass tests indicating they can perceive colors normally. The critical test is the Farnsworth–Munsell 100 hue test, which involves color organisation. Normal humans perform this test very accurately and achromatopsics can exist at chance in this test of arranging hues in an orderly sequence. Failure on the 100 hue test correlates very well with subjective reports that the patients cannot tell what color they are looking at. Because this neurological syndrome is unremarkably accompanied by lesions in a particular region of cortex, in that location is strong suspicion that this extrastriate cortex subregion is the colour-specialist expanse, a view stated forcefully by Semir Zeki. However, we review and modify this concept of a colour module in the following discussion.

Human being imaging studies comparing activation by colour vs achromatic patterns are quite consistent in identifying a ventral occipital–temporal region every bit the color surface area. Originally, this region was dubbed V4 by Lueck and colleagues, who used positron emission tomography (PET) to find the regions of the brain that were preferentially activated by colour. This was later confirmed with fMRI by Zeki and colleagues. The naming of the color region as V4 cortex was washed in analogy with Zeki's previous studies on macaque cortex, in which he proposed that macaque V4 was specialized for color processing. This proposal of color specialization in macaque V4 has been challenged many times and is still controversial, specially due to the inquiry of Heywood and Cowey, who found that lesions in V4 did not accept a major effect on colour discriminations in monkeys. Hadjikhani, Tootell, and colleagues mapped the color expanse in the same manner equally Zeki and colleagues, simply they also measured retinotopic mapping in the same subjects to find out if the color expanse Zeki and colleagues discovered was indeed V4 in the retinotopic framework (Fig. 14). They found that it was quite anterior to V4 as measured with retinotopic mapping. There is no disagreement on the location of the color-preferring area, just on its proper name. Hadjikhani and colleagues added an elegancy to their study by showing that the color region they institute, which they named V8, responded persistently after a color stimulus ceased (Fig. 15). This poststimulus activity correlated with the perception of color afterimages. In this way, it resembled the movement aftereffect activity before observed in MT by Tootell and colleagues.

Effigy 14. Mapping of man V8 cortex in ventral visual cortex with fMRI. The visual stimuli used for mapping were radial gratings that were either black–white or equiluminant color (cerise–green). The activation maps are for the departure between these two stimuli. The of import point is the placement of the ventral activation exterior the region of retinotopically mapped V4 [reproduced with permission from Hadjikhani et al. (1998). Retinotopy and color sensitivity in visual cortical area V8. Nat. Neurosci. 1, 235–241.]

Effigy fifteen. Color afterimages in fMRI of V8 cortex. (a) Activations caused by perceiving stimuli to create colour after images. The fMRI activation for the constant colors condition outlasts the stimulus by 10–20   sec compared to the response to the alternating colors condition considering of the color afterimage. (b) The alternating colors response has been subtracted from the constant colors response to illustrate the time grade of the afterimage activation during the fixation period. But regions of cortex activated by the color mapping stimulus exhibit these long afterresponses to color afterimages [reproduced with permission from Hadjikhani et al. (1998). Retinotopy and color sensitivity in visual cortical area V8. Nat. Neurosci. i, 235–241.]

There are other methods for testing for color activation as well the differencing method used by Zeki and by Hadjikhani. The differencing method assumes that color perception will be associated with activation that is linked to colour but that disappears when achromatic stimulation is used. Implicitly, this method includes the assumption that the neural mechanism for colour perception is composed of neurons that only respond to color and practice non respond to achromatic stimuli. Engel et al. showed that many other areas of visual cortex, including V1, will respond to purely chromatic modulation but will likewise respond to chromatic modulation. This finding in man fMRI is related to recent single-cell studies in macaque V1 that indicate that in that location are many neurons in V1 that respond to both color and brightness. Such neurons could play an important role in color perception simply would be ignored past the divergence image methods. Therefore, the amount of cortex involved in color perception may have been significantly underestimated past these difference methods, a indicate fabricated by Brian Wandell. However, information technology is important to notation that the region of cortex involved in achromatopsia lesions and the region of cortex mapped with PET and fMRI with the differencing methodology are similar.

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John Dalton (1766–1844)

David Knight , in Philosophy of Chemistry, 2012

Publisher Summary

Dalton (1776–1844) was a Quaker, a Dissenter, who lived mostly in Manchester where he was a pillar of the Literary and Philosophical Society. He worked on color-blindness and meteorology. Dalton realized that he and his brother were both unable to see ruddy. He had discovered this, apparently, when sent past his mother to buy some thread matching her grey Quaker apparel; he returned with ruddy, which looked the aforementioned to him. Color-blindness is nonetheless sometimes called Daltonism. He is chiefly remembered for his atomic theory, in which each element was composed of identical and irreducible particles which reacted in simple and definite ratios. He believed that this explained the laws of chemical composition: but contemporary critics found information technology hypothetical, and mostly favored sticking to equivalent weights; and later philosophers, noting that Dalton'due south assumptions about atoms have been disproved, also question the condition and explanatory ability of the "atoms" (he used the word, confusingly, to include what one would phone call molecules) in his theory.

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Human being Adequacy AND PRODUCT Pattern

JOHN CLARKSON , in Production Experience, 2008

four.3 Color perception

Color can be described in terms of its hue, saturation and brightness. When choosing colors for product features, two important bug for consideration are colour contrast (Arditi, 2006b) and color blindness.

Sure combinations of text and background color event in poor contrast. High luminance foreground on a depression luminance background (or vice versa) gives maximum contrast. Colour blindness is the disability to distinguish between diverse colors: Information technology does not mean that people with color incomprehension cannot perceive color (this is extremely rare). Color incomprehension refers to a wide spectrum of effects, but the most mutual class is red–green color blindness, where a person may exist unable to finer distinguish, nether all lighting weather condition, between colors from cherry-red to green in the color spectrum.

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https://www.sciencedirect.com/science/commodity/pii/B9780080450896500095

Genetic Disorders: Sex-Linked

J. Isen , L.A. Baker , in Encyclopedia of Babe and Early Childhood Development, 2008

This commodity summarizes the electric current state of knowledge regarding sex-linked genetic disorders. There is a strong male bias for many babyhood disorders. Genes located on the X chromosome are responsible for many Mendelian-inherited weather, including colour blindness and fragile X syndrome. Although sex activity linkage has not hitherto been demonstrated unequivocally for any complex polygenic disorder, the gender skew in prevalence for autism suggests the presence of either a sex-linked or sex-limited genetic mechanism. Sex limitation may arise if the magnitude of genetic influence differs between the sexes, or it may apply to epigenetic phenomena in which sex steroids interact with autosomal genes. These mechanisms are evaluated with respect to autism, and contrasted to sex-linked models of manual.

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https://www.sciencedirect.com/science/article/pii/B9780123708779000700