j *@ - Sociedade Brasileira de Psicologia

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and a brightness sY' e-Diferencejudgments and ratiojudm entswithout'specialhstructions
are explained as derived directly from opponent color coding systems as cell excitations.
It is not necessary to explain them as being related to sensations. The results of
multidimensional scaling of ratio judgments demnd on the instnzctions given to the
probands. The 5-7 dimensions derived by Ekmu (1914) and Kuehn (1976) are interpretable
as lmique colorsjudged as ratios of the nmounts visible in color sensations.
3. Phenomenolor of color Rnsations
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1 . ln all color sensations six different unique colors are clearly visible in
diferent proportions: bhck, White, red peen, blue, yelow (Hering, 1905). The pro-
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portions of unique colors are easily judged even by :x naive y subjects wit j an . accmacy
of 5% (Hard, 1966). 2. Red/green anà blue/yelow are opponent colors, i.ek they do
not appear 7 at the same time (Herbing, 1905). 3. The lightnes 'of a color sensation is
related to the amounts of chromntic ' unique co 1 ors and
achromntic unique colors black
and white. 4. Color sensations are always spatial, i-e. have a size and a location in the
three dimensional geometric space (Hering, 1905).
ihe problem is to exphin the properties of spatial color sensations from
opponeni color codind and spatial codirlg. An explanation of the phenomena 'by
calculating the one dimensional plameters hue, saturation, and brightness from thç
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excitations of an opponent color coding systems wottld
heed ' lazge neural networks
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for each spatial point to perform the necessary calculations-n e whole phenomenolor
e-qn be expbined by the folowing (color state) hypothesis: each opponent color
coding system presents 'the informntion about the relative amount of unique colors
(red/greeri, blue/yelow and black/white) present in a spatial point. The physical
states corresponding to the unique colors are controlled by the color coding syitem.
since the physical states fulftl the sanie çalfebrk' as the psychological states
measured in the psychophysical experlment they glould be identiluble as physiz
objeds. Fyom the tmlqùe color states (com/onents o? sensations), the perceptlml
P arameters hul, saturation and brightness can Easily be derived as iuptients of tie
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nmounts of colored/white states arid colored/colored states.
4. Saling of color Knsations in humnnm
Ekman (1954) instruded mobands to repo yy the content o : jmj qu;
xjoa s
the seen color às ratios and extracted five dilensions whiqh are interpreted às lmque
colors visible in tlie color sensation calsed by the stimuli. The color attributes hues
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saturaion and brightàess aie simjly related to the proportions of uniqize colors. Tie
natural coloi system is based oh ratio judg'ments witli resject to the amount of unique
colors visible in thè c8lor sensbtions tHerik, 1905; éard, 1966).