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COLOR VISION TEST
ARRANGEMENT TEST (according to FARNSWORTH)

Retinal Neurobiology Lab, Peter Ahnelt, Inst. f. Physiology, Med. Univ. Vienna, Austria

Author: Lorenz Pollak (email)


Quick-Links: Introduction Instructions TEST Interpretation References Links

Introduction

Most color deficiencies are characterized by the congenital absence or abnormality of one or more of the photopigments in the retinal cone photoreceptors. Each show a typical confusion of certain colors.
The most common type of color-deficient individuals are anomalous trichromats. These individuals have three types of photopigments but still make what are considered abnormal color matches eg. due to mutational shifts of absorption maxima.

In a dichromat one of the three normal cone pigments is missing or dysfunctional, so any color is matched with a mixture of two other colors (instead of three colors in normal trichomats).
"protan-" refers to the long wave (red), "deut(er)an-" to the middle wave (green) and "tritan-" to the short wave (blue) receptors in human retinae.

Instructions:

The purpose of this test is to arrange the colored buttons in order, according to color. Begin by choosing a button from the bottom area that looks most like the button on the far left in the gray box, the reference button. All buttons must be placed into the gray box by grabbing and moving them with "mouse-down". After completing this taskclick on <Finished> to see your results. If you would like to begin the test over, click on the <Reset> button.

Caution!: This color vision test is only a simulation and not a calibrated testing method!
Due to the fact that every screen has its own individual color profile and that the surrounding illumination can not be influenced, this procedure is not able to provide a consistent testing environment.
Thus the test results must not be used as a confirmation nor as a disproof of color vision deficiency.

Interpretation

We demonstrate two different ways in which color arrangement tests can be scored.

The first is a graphical representation of the used test colors in a "color space" (the CIE diagram). Each color button is represented by a small circle and all together form a type of ellipse. (In simpler graphical views they form a shape that looks more like a circle.). The position of the circles in fact represent coordinates with particular hues and saturation on the CIE-color triangle.
The small circles are connected by lines following the order in which the buttons had been arranged by the observer.
Individuals with certain color vision deficiencies will tend to make typical arrangements errors.
These errors are lines that cross the center of the ellipse at a characteristic angle which is called a confusion axis of a certain photopigment.
To see those confusion axes in your result diagram click on the corresponding checkboxes.

The second method of scoring the color arrangement test was invented by Vingrys and King-Smith (1988) and provides a more quantitative assessment. It involves determining the angles of adjacent colors in color space, producing a "color difference vector".
The analysis produces three important values:
(1) "Angle" indicates the axis of confusion and therefore the type of color deficiency.
(2) "C-Index" is the Confusion-Index, which is a measure of the severity of the color deficit.
(3) "S-Index" is the Scatter-Index, which is used to assess the degree of scatter, randomness or selectivity in the observer's arrangement. Vingrys and King-Smith claim that these three values are sufficient to discriminate between a variety of congenital or acquired color vision deficiencies.

Type of Color Vision Angle Major Radius Minor Radius Total Error S-Index C-Index
Normal 62.0 9.2 6.7 11.4 1.38 1.00
Minor Error -12.1 9.8 9.2 13.4 1.07 1.06
Protanomal 28.3 18.0 8.2 20.4 1.97 1.95
Protanope 8.8 38.8 6.6 39.4 6.16 4.20
Deuteranomal -5.8 25.4 9.6 27.5 2.99 2.75
Deuteranope -7.4 37.9 6.3 38.4 6.19 4.10
Tritanomal -80.8 16.3 6.4 17.5 2.57 1.77
Tritanope -82.8 24.0 6.4 24.9 3.94 2.60

References

Vishnevsky, E. (1997) The Chromaticity Diagram and Color Gamut Applet (website)

Baro, J.A. and Lemkuhle, S. (1991) InSight2 - InColor v1.01. (HyperCard)

Farnsworth, D. (1943). The Farnsworth-Munsell 100-hue and dichotomous tests for color vision. Journal of the Optical Society of America, 33, 568-578.

Rushton, W.A.H. (1972). Pigments and signals in colour vision. Journal of Physiology, 220, 1-31.

Rushton, W.A.H. (1975). Visual pigments and color blindness. Scientific American, 232, 64-74.

Vingrys, A.J. and King-Smith, P.E. (1988). A quantitative scoring technique for panel tests of color vision. Investigative Ophthalmology and Visual Science, 29, 50-63.

Links

Colorblind Home Page:
http://colorvisiontesting.com/

A new web-based colour vision test:
http://www.city.ac.uk/avrc/colourtest.html

Explaining Color Deficiency:
http://members.shaw.ca/hidden-talents/vision/color/colorblind1.html

Measuring Colour Vision Defects:
http://www.geocities.com/HotSprings/8018/Measure.html

Our site on the "Evolution of Color Vision in Mammals"
http://www.univie.ac.at/Vergl-Physiologie/doc/ret-evol1.html

Vischeck is a way of showing you what things look like to someone who is color blind:
http://www.vischeck.com/vischeck/

Other related websites at the Institute of Physiology, Medical Faculty Vienna:
Functional Retinal Morphology (Research)

Some simple color vision tests
http://members.shaw.ca/hidden-talents/vision/color/colorblind2.html

Munsell Company: Colorimetrics...
http://www.cis.rit.edu/mcsl/online/

Color Science - nice images, interesting links
http://www.physics.sfasu.edu/astro/color.html

ColorVision
http://retina.umh.es/webvision/Color.html#Introduction

Understanding Color Blindness
http://directorylasik.com/articles/understanding-color-blindness.html
(Thanks to Erin Cole)

Cambridge Colour test
http://www.crsltd.com/catalog/cct/

Technical Requirements

Java-Plugin version 1.2 or higher, Java from Sun

Author: Lorenz Pollak (email)