The Psychology of Color
by I.H. Godlove and E.R. Laughlin, 1940
                                                                                               THE PSYCHOLOGY OF COLOR

   The following material has been somewhat condensed, from a talk given by Dr. I.H. Godlove and Dr. E.R. Laughlin before the joint
meeting in 1940 of the Technical Association of the Pulp and Paper Industry, the Inter-Society Color Council, the Optical Society of
America and the American Physical Society (see references:   Paper Trade J.
111, No. 1, 518-25 (1940); Tech. Assoc. Papers 23, 518-25
(1940); Paper Indus.
22, No. 3, 278-81 (1940); (1940 ISCC-TAPPI Symposium on Spectrophotometry; Psychology of Color):

   The psychology of color, as treated herein, does not signify the mood-stimulating values of colors only.  We believe this to be at once a
neglected and over-indulged field; neglected in careful study and utility, but too much indulged in by indiscriminating persons.  For
example:

    "In recent years, these troublous times have made some of us chronically blue.  Our business was in the red.  We were going home
with a dark brown taste in the mouth.  We were unable to look through the old rose-tinted glasses to see the yellow-golden flood again
flowing our way.  The purple depression had us contemplating black mourning for dying business, departed bank accounts and profits.  
But we took a hitch in our belts and carried on, waiting for the rosy dawn, for we lacked the yellow streak.  We toned up our product,
gave it a more healthy complexion, made it more attractive; put more color spice into our sales appeal."

    In these lines we have tacit admission of a mental association of colors with qualities or attitudes.  Depression and despair are blue,
purple or black; joy and good fortune are yellow-golden; hope and dawning light are rosy, though to be in the red means to be in danger.

   These associations are trite for most of us but they are not universal, therefore they cannot be scientifically valid. For example; we
are accustomed to black as a sign of mourning while white is used for the same symbol in China.  More exactly, red is supposed to be a
stimulating hue; green a tranquil one. But greens can be very irritating--solid bright green walls can cause red after-images which are
very disconcerting.  Bulls are supposed to be infuriated by red cloth but cold scientific fact and experiment deals harshly with this story
for bulls cannot see the redness.  What they see is motion and the contrast of light and dark between the object and the background.

   But color has a utilitarian value, as sensible business men, we have recently been putting more color into our advertising, our
products and our packages.  Color is a practical tool as well as an esthetic one if employed with judicious restraint and scientific
control.

    Today color is to be found in milady's kitchen: in her stove, her refrigerator, her cabinet and her breakfast set.  We find pink bed
linens, colored soaps and cleansing tissues.  No longer may we call only men like Dizzy Dean "colorful”; for John Smith is wearing green
shirts instead of white.  He struts the sands in his beach robe like a proud peacock.  He has his desk set matching his office rug and its
tinted walls, and Bill Jones has harnessed the rainbow to his display room.  The mail-order house has converted more of its black and
white catalog pages into chromatic persuaders.

   All these new uses of color are sales makers, but some have not considered the matter carefully.  They have splashed vivid red all
over their advertising pages to gain attention, but thus have made their pictured product look sick and anemic by contrast.  Some
summer drinks are torrid reds and oranges or burnt browns, not cooling colors.  On Broadway, we have been forced to cultivate color
obliviousness.  But some of us have tamed the chromatic urge.  Our catsup is being maintained at a standard color that makes our
mouths water and our meat more savory.  Color in the past has been only nature's advertising; but recently man has gone into the
business, and from the earthy rocks brought forth vivid pigments, from the viscid black tar of the coke ovens he has developed his
myriad of dyes far surpassing the ancient colors of Joseph's cloak.

   The only way to be sure of being right about color use is to have careful reports by trained observers under controlled experimental
conditions.  Such results have been forthcoming from the laboratories of advertising psychology of Columbia University and the
Department of Psychology of the University of Nebraska. This work is in sharp contrast to a mass of statements, made in many books
and pamphlets, which are without experimental or practical basis, but which by inspiration, and quotation and requotation, embraces
supposed psychological relations or colors.

    Color is a matter of sensation and perception, which is the province of psychology.  It is only when we feel the need of tying it to our
physical concepts of objects, molecules, wave lengths and intensities that we are forced to go into the physics of color.  In particular,
when we require accurate measurement, we must consider the physics of color.

   The psychological aspect of color might be most simply defined as whatever we see; the physical aspect involves intellectual
concepts.  To illustrate the purely visual or psychological method, we have a mid-gray sample which gives equal contrasts with white
and-black.  Remembering that physically a theoretically white sample reflects 100 percent of white light and a black sample zero per
cent, the mid-gray should reflect 50 percent, but it does not.  Its reflection is only l8 percent.  To put this the other way round, a sample
reflecting about half the incident light looks almost white.  The psychological differences between mid-gray and black and white are
equal; the physical differences are as 82 percent to l8 percent.  Conversely, the 50 percent reflecting sample, physically differing equally
from black and white, is visually close to white, very far from black.  Obviously, the eye and physical measuring instruments operate
differently.  In a ten-step scale of grays, extending from black to white, which looks equally graded to the average eye, the reflectances
are:  0.0, 1.1, 2.9, 6, 11, l8, 27, 39, 54, 73, and 100 percent. It is also noted, however, that the exact scale varies with the background on
which the grays are seen.

    In two circles each having 20 colors of varying hue, one has the consecutive samples differing from each other by a constant hue
difference; it looks "right" to the eye.  The other is set up with a physical criterion; the dominant wave lengths of the colors are equally
spaced.  This set does not appear "right" to the eye; some contrasts being very large, others, imperceptible.

    In a rough sense, color may be thought of as an "effect" which has a "cause."  This cause is light energy.  Let us give a homely
analogy to illustrate a similar relation of cause and effect.  A pickaninny hears syncopated music; he starts to jig, the music is the
cause; the jig, the effect.  Scientists use the terms "stimulus" and "response."  The stimulus, light energy, evokes or stimulates the
response, which we call color.  Under given conditions, a given light stimulus always evokes the same color; but the converse is not, in
general, true; that is, two identical colors may be evoked by different stimuli.  The stimuli are then said to be equivalent, and the colors
are said to match.

    In practical colorimetry, because of the difficulty of accurate measurement of sensations, equivalent stimuli are measured.  In one
method of colorimetry, sometimes called "trichromatic analysis", the sample color-stimulus is matched by three mixed "primary"
stimuli.  A specification of the color is obtained in terms of the relative amounts of the three primaries expressed as "trilinear
coordinates", x, y and z; and with these, one measure of intensity or brightness.  This measure is neither purely physical nor purely
psychological. From these considerations, and other related ones, the following table with its terms and relations is arrived at.  This is
condensed from one prepared by Dr. Deane B. Judd.
           
                                                                                Color and its Attributes and Correlates

Realm                                              Physics                                     Psycho-physics                                                Psychology

Thing referred to:                  Radiating source                            Lumlnating source                               Color sensation and perception
                                          (Color stimulus)                                      (Light)                                                                (Color)

Attributes                                1. Radiance                                      1. Luminance                                                 1. Brightness
                                                                                                                                                                                      (Lightness)

                                          2. Spectral distribution                    2. Trilinear coordinates                                2. Chromaticity
                                              of  radiance                                        
                                                                                                           a. Dominant  wave length                               a. Hue
                                                                                                           
                                                                                                           b. Purity                                                               b. Saturation

     Unfortunately, there is great confusion in the use of color terms by various groups; and the terms of this table are not used as they
are sometimes employed in the dye, textile and paper industries.  Explanation of these terms and relations may be found in various
papers by Dr. Judd.

     The correlations of color and its physical stimuli, and  the analysis of color into its attributes does not present the entire story.  
Additional physical quantities are also to be considered: angles of illumination and viewing of the sample, also the condition of the eye of
the observer, not only at the moment of viewing the sample but for some time previous to this.  This state of "adaptation" of the eye
depends chiefly upon the reflectance of the background of the sample and upon the type of illumination.  Obviously, an object, which in
neutral light appears violet, may appear red when seen lighted by a source having an excess of red-generating waves, as an
incandescent light; and it may appear blue in the light of a clear blue sky.  These facts permit of simple physical explanations.  Other
facts cannot be so simply treated.  Artists and advertising men know that to make a cube look vermillion, the high-lighted face must be
painted scarlet, the shadowed face crimson.  This "hue-shift" is an effect well-known also to scientists, and is an effect of intensity of
illumination which must make the light stimulus reaching the eye from the object very different.  A red cherry is red in bright sunlight or
in twilight, in blue skylight or in orange candle light, even though the physical energy reflected, wave length for wave length, to the eye,
varies greatly in composition.  The leaves of a book are "white", whether the light reflected from them is the orange light of a candle, the
green-yellow light in the woods, or green light from a lamp shade of that color.  White objects are thought of as reflecting all of the light
that strikes them, and black objects as reflecting none; but a shadowed white paper is still "white" when it reflects only one per cent of
the light that it would under strong Illumination.  Also, it is said to be "white" when the light reflected is no greater than that from a piece
of black velvet when the latter is strongly illuminated.  But there is work to show that if these are seen under  conditions such that the
objective situation is not known, the effect disappears.  For example, if the paper is weakly illuminated and the velvet strongly lighted
and the two seen through two holes in a screen, they may appear to be grays of equal brightness.

     Some scientists explain the "color constancy" of the objects of vision as resulting from the mechanism of perception. The
Impression produced in consciousness by a color stimulus is thought to depend to a marked extent on knowledge of the objective
situation, the brain having an astonishing capacity to reconstruct color perception from the immediate sensations on the basis of
remembered colors.  A white object is remembered as white regardless of the stimulus reaching the eye, because it is recognized and
known to be white.  These workers say there is a "painting over of things with memory color," which makes the objects in any light have
their "daylight colors."  When the objects are not recognized, different colors may be seen.  Judd, from recent work (1) has arrived at a
different explanation.  He accepts perception through the aid of memory as a secondary factor in color constancy.  He finds that the
physical or physiological process of retinal "adaptation", that change in the sensitivity of our visual apparatus which results from
continued stimulation, produces the same effects; and he stresses the importance of the background against which colors are seen, in
conditioning adaptation.

     Professor Helson of Bryn Mawr, a psychologist who has collaborated with the physicist Judd, has done some important work which
also stresses the importance of the level of reflectance to which the eye is adapted.  This depends chiefly on the reflectance of the
background.  Working with non-selective samples, he found that ones lighter than the adaptation reflectance are seen of the hue of the
illuminant, objects darker than the adaptation reflectance have the hue complementary to the hue of the light source.  His work throws
much light on the meaning of the color of an object.  To the average layman, the color of a cherry is an inherent property of the cherry;
the common sense view is that the redness belongs to the cherry.  To the physicist, the cherry is a selective absorber and reflecter of
radiant energy, selecting chiefly green for absorption and reflecting most of the red light which reaches it from any source.  He will not
admit  that it remains red, say, in green light; if the source emits only green light and no red, the cherry will absorb nearly all and appear
nearly black.  To the psychologist, the cherry is an object which modifies the stimulus from a light source; but its perception involves
other complicating factors.  When the modified stimulus reaches the eye and brain, the response is the perception called "cherry red."  
Both points of view get somewhat afield from the layman's common sense view of the color of the object.  The concept of color
constancy is to a certain degree a concession of the psychologist to the common sense view; he rationalizes this admission by
attributing the fact, that the cherry is seen as red in nearly all ordinary lights, to memory of the cherry color or to certain perceptual
factors.  Helson and Judd now find that there is constancy of color only when the illumination is very homogeneous, or the object very
selective, or when the reflectance of the object happens to be the same as the adaptation reflectance, which depends chiefly on the
background.  Mere change in background is sufficient to change the color: a medium gray seen on a white ground in red light appears
blue-green, while on a black ground it will look red.  Thus again the hard facts of experiment get us further away from the common
sense view of the color as belonging to the object.

   When a stimulus reaches the eye, its response, the color, does not reach its final value instantaneously.  It requires a definite time to
reach equilibrium.  By adaptation is meant the relatively slow process by which the eye accommodates itself to changes of light
intensity or quality by changes in its sensitivity.  Getting "accustomed to the dark" is an adaptation to change of intensity; the change
occurring when colored glasses are put on is an adaptation to change in the spectral character of the illumination.  Adaptation is
essentially a retinal process. The sensitive surface of the eye, the retina, is made up of at least five layers, of which the second consists
of some 150,000,000 "rods" and some 7,000,000 thicker "cones', both of which are nerve cells.  The rods are essentially the organ of
brightness sensitivity, the cones the organ of complete color sensitivity.  The sensitization of the retina is known to be connected with
the presence in the rods of a pigment known as "visual purple", which recently has been shown to be generated from Vitamin A.  Thus
night-prowling animals (owls, rats, moles) have retinas almost wholly deficient in cones, but containing rods which are exceedingly rich
in visual purple.  On the other hand, certain persons are unable to regenerate the pigment, hence are afflicted with "night-blindness";
they are unable to see in faint light, as the normal person can after twenty minutes or more.  They are then like certain other animals
(doves and chickens) who lack visual purple and are night-blind.

    In the time interval preceding final equilibrium, effects known as "after-image" and "contrast" effects occur. They are positive and
negative effects in time and in space, respectively.  The after-image is an oscillating series of phases, alternately darker and lighter
than the surroundings, which follow after the stimulus has been cut off.  Of the bright phases, two have the same hue as the primary
stimulus, and one is complementary.  The latter is the ordinary negative after-image commonly seen by looking steadily for 15-20
seconds at a brightly colored spot and then abruptly looking at another spot on a white surface.  After-images of colors appear at
different rates.

   Simultaneous contrast is a reciprocal alteration of adjacent colors in such a direction as to increase the difference which would have
existed between them without contrast.  Contrast causes colored areas to look lighter on dark backgrounds, darker on bright
backgrounds.  The chromatic contrast is greatest when the brightness contrast is least, the general effect being toward a
complementary hue.

    Place a red circle half on a yellow ground and half on a blue ground.  The complementary grounds are seen to tinge the circle in
opposite directions.  Similar modulations can be seen with various other color combinations, as green on these grounds, or red on
green and on red-violet.  A purple circle half on a stronger purple and half on gray demonstrates that the chromatic ground "kills" the
saturation of the circle color.  This "killing" of one color by contrast with another color occurs only too commonly in advertising, and
often in the coloring of products and in decoration.  A careful consideration of possible contrast effects will not only prevent such
tragedies but will suggest desirable enhancing effects.  A great deal of what artists call "vibration" or "life" in paintings is due to
deliberate or
inadvertent use of felicitous contrasts.

    The subject of Illusions is a very interesting one. The drawing of the prohibitionist's top hat appears to be higher than it is wide.  
Actually, height and width are objectively equal.  Many such illusions can be found in books on the subject. Briefly, it is found that vertical
lines look longer than objectively equal horizontal ones; of two similar figure components, uppermost ones look larger than lowermost
ones; a figure length embracing more details or features looks shorter than a less complex length without detail.  Turning to illusions
involving color, after-images and contrast effects might be broadly so considered. Others are due to defects of the eye considered as
an optical apparatus.  One of these, called "chromatic aberration", is exemplified in the appearance of red and violet fringes along
the edges of a very bright white object seen against a white background.  Certain "snake figures" and others, seen when looking at a
bright sky, are due to the shadows of the blood vessels of the retina.  The blue and violet haze which hangs about mountains is due to
scattering of light by very small particles. Similar effects and the contrasts involved in shadows give us our criteria for estimating
distances and the perception of depth, effects which are known as "aerial perspective" and "illumination perspective." An extremely
interesting illusion, involving color effects, difficult to explain by purely physical phenomena, is known as the Illusion of Ragona Sclna,
and is quoted by Frank Alien. (2)

    Certain visual facts which appear to transcend the realm of physics are encountered in the field of colored movies. Colored pictures,
as opposed to black-and white, have several features which will militate for their increasing use.  They carry greater conviction.  Even
the bill posters and lobby posters advertising black-and-white motion pictures are uniformly in full color.  The enhancement of color in
the appreciation of comedy is illustrated in our Sunday comic strips.  Artists always prefer color to black and white in spite of the
greater difficulty and cost of the chromatic medium.  It has been stated that motion picture actors cannot perform satisfactorily in a
black and white set, so that producers have to go to the expense of normal colors in the studio, only to have the normal camera reject
the color. Color adds very much to the stereoscopic impression of depth, enhancing "atmospheric” or "aerial perspective."  This is
strikingly illustrated by water scenes, moreover when the impression is so vivid that one can almost feel the coolness of the sea air.
Illustrations of the illusion of depth and aerial perspective are given in two papers by Ames. (3)

    An interesting psychological problem was introduced by the early Technicolor two-color process.  Three primary colors are required
to be mixed to obtain complete chromatic reproduction for normal individuals.  In the early Technicolor process, the blue-violet primary
was dispensed with, and an orange-red and slightly bluish green only were used.  If any is omitted, the blue-violet is best, because the
rendering of "flesh tones is not much interfered with, and because people are very familiar with the colors of objects under yellow
artificial light.  The puzzling question remains as to why and how one is satisfied by a greatly restricted range of colors in the
reproduction.  The answer used to be given in terms of the theory of memory color and color constancy; but we have seen that these
questions have not yet been fully settled.  Physically, two-color reproductions cannot include all the colors of a scene.  In fact,
moderately objective study showed that the reproduction was far from perfect. Large sky areas and grays were very greenish.  But the
"flesh tones" and the yellows and oranges of fruit appeared very natural, and the blue of the field of our flag was very true.

    Certain color problems involve a combination of physical, physiological and psychological factors; such are the problems of legibility
of colors on various backgrounds, and problems of eyestrain and fatigue.  One frequently hears that “green is easy on the eyes.” But
what is in fact the best light?  Yellow-green light gives the greatest brightness for a given amount of energy in the stimulus; and in
certain experimental work, green was found only moderately good, and fatiguing.  Here “fatigue” means an increase of ache in the
muscles which move the eye; it is not a matter of tiring or damaging the sensitive surface. Within ordinary Illumination limits, the retina
is not subject to fatigue of that sort.  Continued stimulation causes the changes already discussed as adaptation, after-images and
contrast effects.

    Although legibility is of great importance in reading billboard advertising, road signs and automobile license plates, it can be most
conveniently studied in relation to the reading of writing on paper.  The outstanding fact on which all agree is the necessity of sufficient
contrast between the paper and printed matter.  Of the contrasts, certainly the brightness contrast is the most Important.  Remember
here, that "brightness” is not the same attribute of colors as the one called by that name generally in the dyestuffs industry; in the case
of colored paper, it is the lightness or darkness which corresponds to the relative amounts of light reflected.  The brightness difference
should be as great as is practicable.  Since inks are usually dark, the paper must be light, the lighter the better.  For example, the blue or
blue and red dyes used to counteract the yellowness of stock in tinted "white” papers decrease legibility slightly, for, although they
make the paper appear "whiter" by a psychological effect, they actually lower its reflectance.  The addition is no doubt desirable,
however, and the white effect compensates for the decrease in legibility.

    Hue and saturation are less important here than brightness.  When there are rulings, initial lettering or other decorations, it must be
remembered that the color of the typed matter or other message Is still the important element.  It. must  be as legible as possible; the
other elements must be secondary.  Short of the use of colors of nearly spectrum purity, saturation is of minor importance.  Probably
pale colors are better than strong colors of the same reflectance.  Turning to hue, there is some advantage for yellow over other hues
and white.  Yellow, as compared with white as a background, reduces the extreme blue and violet rays which are not focused on the
retina at normal reading distances.  The long waves stimulating reds are also not focused when the eye is focused as usual for the
brightest light in the middle of the spectrum.  This lack of focus for both long and short rays has already been discussed under the
name “chromatic aberration."  Because of this, when there are rulings, or decorations, the use of both red and blue must be avoided.  If
required to focus on both, constant changes of accommodation result in fatigue.  The hues of all rulings should be fairly close together;
they should not contrast too greatly with the paper color, and should resemble it more than the ink color.  This is because it is the
writing which must be legible; and all of its contrasts must be greater than the others.  The rulings should be light to medium, since the
ink is dark and the paper light.  In the case of black ink on a white sheet, the decorative color may be medium.  If red, which has great
attention-getting value, is used, it should be preferably a yellowish-red, since this can be obtained readily in printing inks of medium or
light value, bluer reds being too dark.  Such reds will go well on a cream background.

   A great many, but conflicting references can be found giving the relative legibility of black figures on a white ground as compared with
the reverse.  However, it is generally agreed that both these and the yellow-black combinations rank high. Guertin (1926) studied
legibility on billboards.  Of the dozen combinations he studied, he found that all the best ones had a brightness contrast amounting to 60
to 80 per cent of the maximum possible.  But further, black on a yellow-orange was ahead of black on white, while the yellow-orange on
black was third and white on black fourth.  These results show that saturation contrast is of some help.  But Guertin also found that hue
contrast is of little value; green on red and red on green being last, as others have also found.  The Munsell "Color News" of July, 1926,
reported this work, using black on a cream stock with a medium value purple decoration, and printed some numbers of the issue in
black on a dark gray stock to show how poor legibility is when the brightness contrast is too small.

    There are other, mainly physiological criteria on which the value of background colors may be judged.  Ferree and Rand (1922-4)
made some excellent studies with a test object viewed on white paper illuminated by colored lights.  The value of the color was judged
by several criteria: (1) Visual acuity; (2) power to sustain acuity, say for 5 minutes; (3) speed of discrimination; (4) tendency to produce
ocular fatigue and discomfort.  Yellow ranked at the top in all the tests; it was closely followed by the ruddy yellows (up to orange).  
Yellow-greens and greens were fairly high in the first three tests, but not so high in the fatigue test.  Deep reds, blue-greens and blues
were only fair in tests 1 and 3 and poor in the others; hence, they should not be used for backgrounds.  Yellow light was found less
fatiguing for reading than red, blue or green when brightness and saturation were equalized.

    Since all agree on the low esthetic value of green-yellows, if yellows are used for backgrounds they should be on the ruddy or orange
side rather than greenish.  Yellow is also the "joyous color", standing fairly high in lists of color preferences when combined with blue,
violet or purple.

    Closely related to legibility is the subject of the attention-getting value of colors.  Work by Gale and by Adams found the attention-
attracting value of black, red and orange high, and yellow and violet low, on a white background.  Probably these results could be
predicted from the various contrasts obtainable when using the various commerically obtainable print inks.  It must be remembered
that colors may be a distraction; for example, a too-saturated background may get attention and divert it at the expense of the
advertising message.  Also, a saturated red and yellow combination may do very well on a gas station or a five-and-ten store, but not so
wall for other purposes.

    In the psychology of color and its applications we must include the broad field of "color preference", the appropriateness of colors
and "color harmony."  Some very commonly quoted preferences include the statement that men prefer blue and women red.  Most of
the older quoted data must be questioned because the experimental work more or less ignored the existence of three attributes of
color, considering only hue.  Various authorities contradict each other as to the preferences of men and women, or both together; and
some state different preferences when the attributes other than hue are equalized and when they are not equated.  Much more valid
work is that of Guilford. (4) He varied hue and kept the other two variables, brightness and saturation, constant.  In an early study of the
question whether the pleasantness of single colors can be used to predict preferences for color combinations, his results answered
the question in the affirmative for men; but of the women he said: "The so-called feminine trait of non-predictability seems to be
revealed in abundance here."  Using 464 men and 815 women, he found that blue ranks highest, with red and green next.  He found light
colors preferred to dark; but preferred most at the lightness at which they can be obtained saturated.  The "cool" colors and the reds
are at their best saturations when dark; the "warm" colors, except the reds, are at their best saturations when light.

     Guilford's results lead to the much-abused subject of "Color Harmony."  Reviewing Guilford's work, similarities were noted to studies
published in a series of articles. (5) If the lightnesses of a series of common pigments or dyeings of 20 suggestive hues at their
lightness levels of greatest saturation are observed, a "natural sequence" is found, beginning with yellow and proceeding through
green, blue, purple, and red and back to yellow.  The lightness goes down toward the greens, is lowest at purple-blue, and comes up
again through red to yellow, in a broad v-shaped series.  Any sequence of hue and lightness or darkness opposite to this "natural"
sequence, as dark green-yellow and light blue, is an "unnatural" sequence.  It was found, in experiments using art students as
observers, that practically all the harmonious pairs of colors are in natural sequence; and practically all the color pairs in unnatural
sequence are bad.

    The classification of color schemes generally follows a classical outline which distinguishes "complementary" and "analogous"
color combinations and others.  In the terms of a visually equally stepped 20-hue circle, contrasts of 7 to 10 steps are complementary,
contrasts of less than 5 steps are analogous.  The latter frequently occur in nature.  The Rule of Avoidance of Intermediate Hue Contrast
is that, with certain provisos, either complementary or analogous pairs of hues harmonize, but intermediate pairs are nearly always
unpleasant.  An example of a complementary pair is yellow and blue; of an analogous pair, orange and yellow.  Red with yellow is
intermediate, and, according to the rule, usually unpleasant.

   Another broad rule is called the Rule of Appropriateness. This is based upon an assumed production of dominant moods in the
beholder through the proper choice of colors.  The colors must, of course not be incongruous with the desired mood. A cold one, as in a
seascape, can be produced only through a predominance of blue; or a gorgeously warm one in a scene of oriental pageantry or Spanish
revelry, through the use of red and yellow or orange. Pastel colors do not seem to fit a hunting lodge or the stationery of a contracting or
legal firm, where the appearance of solidity or durability is desirable.  One would not color a boy's bedroom like the boudoir of a
sophisticated lady.  Dreary old rose or dull blue drapes in a dining room do not help digestion like brightly papered walls and bright
drapes.  A brilliant yellowish red can be used on chain-grocery stores, but not on exclusive specialty shops.

    Concerning the appropriateness of colors, the best extant data are probably in a thesis by Miss Colllns quoted by Poffenberger in his
"Psychology in Advertising" (1932).  One hundred people were asked to associate color pairs, which were exhibited to them, with
certain words denoting abstract qualities, as "luxury", and with commodities, as "perfume."  Mere chance would give 5 answers
correlating a color pair with a quality or commodity.  In the case of "cleanliness", ten times this number of positive associations
occurred with the combination yellow and blue.  Thirty-three votes, over six times chance, correlated coffee with yellow and orange of
low saturation.  The yellow-and-blue combination which correlated so well with cleanliness, was 21 percent positive for soap; this is
over four times what may happen by chance.  Luxury and jewelry both correlated best with the yellow-purple pair.  Yellow, a color
ranking low in preference when alone, was the highest in combinations when judged by appropriateness; orange was second.

    "More Business" for October, 1939, reported the best sellers among colors for stoves, toilet sets, plumbing, sanitary wares and
interior paints.  Green sells the most fountain pens The warm colors have the most appetite appeal, red wrappers sell the most candy
bars.  A "color consultant" has introduced purple billiard tables Instead of green; another has introduced yellow baseballs.  Both he and
a manufacturer of crayons claim increased visual acuity for yellow.  An English road builder built a yellow highway to reduce glare.

    Another interesting field of color psychology is that called "chromo-therapy", a real or alleged healing by colored light, including the
cure of mental cases.  It must be remembered that light, when absorbed, induces chemical reactions or is converted into heat.  Such
reactions are responsible for sun tanning, erythma, the destruction of bacteria and the stimulation of the nerve endings in the skin
which increases resistance and heightens the general tone.  Effects claimed for red light may be chiefly due to the infra-red or heat rays
of slightly longer wave length, and effects claimed for blue or violet may be due to ultra-violet, which is very active chemically.  That the
effects vary quite specifically with wave length is highly doubtful, except for two general variations with wave length which are opposite
in sense: (1) The photo-chemical efficiency of light for most reactions increases with decreasing wave length, becoming great for ultra-
violet; (2) the ability to penetrate tissues increases with wavelength, so that only infra-red and red may be considered penetrating.

    Many of the present data in this field are simply old data quoted and requoted.  At a very early date it was found by Doegal and
Jegorow that the circulation of the blood is very markedly changed by the action of green light irritating the eye. Fere (l888) found
respiration 19 per minute in a yellow light, 17 in green, and only 15 in red, but fuller; while in darkness it was extremely weak.  In work in
which persons were kept two hours in various colored hospital rooms, Triwus (1900) found  slower and weaker pulses in all chromatic
lights than in white light   Violet was the most depressing, red the least; other colors were intermediate, except for yellow which had no
effect. Such results, if confirmed, might afford a physiological basis  for the mood-stimulating values of colors to which we have alluded,
which was first brought into promlnance by the poet Goethe in his "Theory of Colors."  Ponza experimentally found blue soothing, red
exciting.  Daitsch and Kogan (l894) from their experiments concluded that red light weakens metabolism, green slows some but
accelerates other destructive processes; yellow, and especially violet light, induce the maximum of energy in all vital processes.

   Two of the most recent papers in this field are by Drs. Deutsch and Vollmer, (6), who reach more or less opposite conclusions.  Dr.
Deutsch noted changes in blood pressure, pulse, etc. of patients suffering from pathological states, when in rooms lighted by red or
green windows.  One patient was benefited by red light and made worse by green; but another reacted in just the opposite way.  The
fear of snakes, incidentally, was alleviated in this way.  Dr. Vollmer found no evidence for any biologic effect of a particular wave length.  
In a few eases in which a color is correlated with a specific biological result, he showed that the effect is not strictly a color effect.  For
example, ants prefer red illumination, not because it is red, but because it approximates darkness.  On the other hand, Dr. Vollmer must
apparently be reminded that, because the luminosity of extreme spectral red light is very low for us, it does not at all follow that it is low
for ants.

    The Chinese were said to have used red light for centuries to cure smallpox.  The treatment was common during the Middle Ages,
and a son of Edward I was said to have been successfully treated.  Later Finsen, the "father of light therapy”, used the treatment.  
However, the fact that a number of soldiers confined in a dark dungeon recovered from smallpox without the usual pitting, along with
other results, makes it probable that the effect of red light is a purely negative one.  The failure to cause pitting and setback in the
disease is probably due to exclusion of the more chemically active ultra-violet light contained in ordinary Illumination from the sun.  This
was one of Dr. Vollmer’s iconoclastic conclusions.

    There is, however, one color effect of the hospital which will stand scientific analysis.  The Leipzig surgeon, Heller, (7) found the
illumination of the operating room glaring and confusing, due to the high reflection from the white walls which supply the field
surrounding the operation.  He described strikingly the characteristic situation in which the surgeon tries to work.  "With equally bright
illumination of the wound surface and the operating room entirely In white, as results from natural daylight illumination, the wounded
area is actually the only dark area in the whole room, and the wound itself, on account of the depth to which we must work and contend
with operative difficulties, is the darkest part of this area."  From practical and theoretical grounds he chose for the operating table a
gray whose reflecting power was the same as that of the wound, which he took at 8-10 percent.  For the smocks he chose a somewhat
lighter gray, of 20-30 percent reflectance.  These conclusions are confirmed by the scientific work of Schoenfelder, (8) who found that
the most favorable field for color matching and similar work has its brightness equal to that of the colors being matched. Deviations
toward either lighter or darker surroundings increased the errors, as Heller had found.

References:

(1) D.B. Judd; J. Opt. Soc. Amer.
23, 12-4 (1955); H. Helson & D.B. Judd, J. Exp. Psychol. 15, 380-98 (1932).

(2) F. Alien; J. Opt. Soc. Amer.
9, 575-88 (1924).

(3) A. Ames, Jr.; J. Opt. Soc. Amer.
10, 137 (1925); The Art Bulletin 8, 5-24 (1925).

(4) J. P. Guilford; J. Exper. Psychol.
17, 342-70 (1934); Psychometrlka 4, 1-23 (1939).  See also Guilford et al., Amer. J. Psychol. 43, 469-
78 (1931);
45, 495-501 (1933); 48, 643-8 (1936).

(5) I.H. Godlove, Amer. Painter and Decorator 12, No. 5, 22-3; No. 6, 26-7; No. 7, 25-8 (1935).

(6) F. Deutsch; Folla clin. orient.,
1, Fasc. 3-4 (1937).  H. Vollmer;  Archiv. Phys. Therapy 19, 197-211, 252 (1938).

(7) Heller; Bruns Beitr. Klin. Chir.
134 (1925); 139 (1927).

(8) W. Schoenfelder; Z. Sinnesphysiol.
63, 228-51 (1933).  See also Matthaeis; Pflugers Archiv. 210, 23 (1925).



                       
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Dr. Isaac H. Godlove (1892-1954)
Leader in Color Science and Its Application to Human Psychology
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