Essay by Roy R. Behrens
Surveillance and camouflage are intrinsically intertwined—they evolve in lockstep. Whenever surveillance advances, deception must adapt in kind. Likewise, when challenged by new kinds of camouflage, surveillance must be redefined to see beyond or through those ploys.
Put simply, surveillance is a “seeing eye.” Whenever detection is thwarted—as is an all-important goal of camoufleurs—it succeeds by eluding the powers of a watchful entity, whose visual apparatus may differ greatly from human surveillance, with or without technological aids. The eyesight of a hunter, for example, differs from that of a white-tailed deer. Safety orange hunting outfits, while blatantly apparent to humans, are imperceptible to deer. At the same time, both deer and people are readily fooled by background matching and simulations of foliage.
How have we become attuned to this sensory pas de deux between surveillance and deception? Despite the current online myth that Pablo Picasso invented modern camouflage, it is far more likely that its originator was an academically trained, turn-of-the-century painter named Abbott Handerson Thayer. His initial groundbreaking discovery (first announced in 1896) is known as countershading or, less commonly, “Thayer’s law.” 
Simply, whenever we encounter things, we default (because of how our brains are built) to the assumption that illumination comes from above, with diminished lighting (or “shading”) below.  All of us resort to this daily, as when we use computers to make so-called “drop shadows.”
Going further, Thayer realized that, in natural camouflage, a wide range of animals benefit from an inverse coloration scheme (an inverted drop shadow), by which they have evolved to be light-colored on their stomachs (he called it “the meaning of the white undersides of animals”) and progressively darker toward the top.
In countershading, the shading produced by the overhead sun is counteracted or cancelled out by this inverse coloration, as a result of which an animal looks less solid, less substantial—less “thing-like.” When this is combined with a “freezing” response (remaining strictly motionless, since movement is the great spoiler of camouflage), the animal has an increased chance of remaining undetected.
Among artists, the shadow effect is synonymous with shading, a technique that Thayer was masterful at. Indeed, he was so skilled that not only could he make flat surfaces appear three-dimensional, he could make objects disappear—eggs, small carved wooden duck decoys, even raw sweet potatoes—merely through countershading.
Thayer’s ability to “paint out” solid objects is amply verified by contemporaneous eyewitness accounts, such as a report that was published in the Boston Evening Transcript in 1897.  At an earlier conference in Cambridge MA, Thayer had demonstrated countershading to a group of ornithologists, and one of the attendees wrote: “He placed three objects of about the size and shape of sweet potatoes, horizontally on wires a few inches above the ground. They were covered with a sticky material, and then dry earth from the road where they stood was sprinkled over them to make them the same color as their background.” The undersides of the two end objects were painted white, and the paint was then carefully mixed with the earth to create a gradual blended effect.
Another eyewitness (present at the same demonstration) recalled: “When viewed from a little distance, these two end ones, which were white below, disappeared from sight, while the middle one [which lacked countershading] stood out in strong relief.” Some of those in the audience
could hardly believe that the striking difference in the visibility of the three potatoes was entirely due to the coloring of the underside, and Mr. Thayer was asked to color the middle one like the two others, in order that the effect might be observed. Mr. Thayer complied…[and] the effect was almost magical. The middle potato at once disappeared from view.
A few photographs of Thayer’s countershading demonstrations have survived. Reproduced here are two from a famous (albeit controversial) book, painstakingly written and illustrated by Thayer and his son Gerald Handerson Thayer (the book’s author of record). Titled Concealing Coloration in the Animal Kingdom: An Exposition of the Laws of Disguise Through Color and Pattern: Being a Summary of Abbott H. Thayer’s Discoveries, it was first published in 1909, followed by a second edition in 1918. 
The captions for these photographs claim that both are images of two wire-mounted “bird-models,”
side by side, one of which has been countershaded (or, to use the phrase the Thayers preferred, “obliteratively shaded”), the other one not. Both photographs were made “out of doors against bare ground.” The Thayers assert that the countershaded model in the top photograph is “faintly visible” on the right, but that in the bottom photograph they have outdone themselves, such that the countershaded model is invisible because it “is still better ‘obliterated.’”  In the first photograph, if a model is visible on the right, it is faintly so at best. A year earlier, they had published another photograph, in which the second wire stand is slightly more evident, but the duck remains elusive.
Some people have openly questioned the presence of the countershaded ducks in these photographs, a response the Thayers could well understand. “The reader will have to take it on faith,” they caution, “that this is a genuine photograph, and that there is a right-hand model of the same size at the other.”
The likelihood that the models were actually present is supported by another set of photographs that appeared in Bird Lore, a journal of the National Audubon Society, in 1921 (the year that Abbott Thayer died).  These photographs replicate the same countershading demonstration, but the set-up is not by the Thayers but by naturalist and bird artist Louis Agassiz Fuertes, who was a friend and student of Thayer, as well as a highly skilled painter.
Fuertes’ photographs are more helpful than the Thayers’ because he provides an additional step. In the largest of the three images (at the bottom), we see a set-up comparable to the earlier ones. There is a model on the left that lacks countershading and is highly visible; while on the right (we are told in a caption) there is a second model that has been countershaded and, as in the Thayers’ examples, is all but invisible.
But there are two other photographs as well: The small one at the top right shows the very same models (one countershaded, the other not), but because they are inverted and lit from above, both are clearly visible. The remaining photograph (at the top left) is the most revealing of the three. It is the very same set-up as in the large photograph (the same two models side by side, correctly positioned), but this time Fuertes has graciously placed a white card in the background, behind and between the two models, as a result of which we can see a portion of the profile of the camouflaged duck.
Thayer applied countershading to other objects as well. For example, he once countershaded a small cast of the Venus de Milo, which he installed in a display case in the town hall at Dublin, New Hampshire. He precisely lit the statue with alternating light sources (above and below), so that “it was the
delight of the school children to press the buttons and [by that] make her come and go.” 
In 1902, in collaboration with Gerome Brush, he was granted a US patent for the use of countershading
to make a ship less visible. As described by Brush’s sister, this system was analogous to “the general coloring of a seagull, worked in two shades of gray and pure white, the under part of everything being painted white. The side surfaces were gray, the upper surfaces a slate color.” 
He also experimented with the use of countershading in theatrical productions. A recent discovery is a pair of Thayer photographs that show a model in a skin-tight body suit, standing inside a large specially lighted box.  The model has been countershaded, just as Thayer had attempted before with the Venus de Milo. In one photograph, the source of light is from below, and the figure is clearly visible. In the second, the light is coming from above, with the result that the figure can only be seen very faintly (yet, unlike the ducks, it can indeed be distinguished).
In 1914 in the American Journal of Psychology, the eminent psychologist Edward B. Titchener praised a countershading installation (a photograph of which survives) that Thayer had donated to Harvard. It consisted of a stuffed tiger in a case that was expertly lighted. When illuminated unnaturally from below, it was clearly visible, but when lit from above like the overhead sun “the animal has lost its solidity, has become amazingly transparent, and merges as a color-pattern into the background.” 
Paul Feeley (an American artist and teacher who had no connection to Thayer) once wrote that “Art is always about turning two into three or three into two.” The same could be said of camouflage. Countershading turns two things into one (as does blending or background matching) in the sense that a figure no longer stands out. It exemplifies what might be called high similarity camouflage, or unit-forming (a term borrowed from Fritz Heider, a psychologist who used it in an essay on camouflage, cubism, and gestalt theory). 
But Abbott Thayer made other discoveries about surveillance and deception that could be more suitably classified as high difference camouflage, or unit-breaking (Heider again)—turning one thing into two, two into three, and so on. This was described very clearly in an article written by Thayer’s son that was published in 1908 (the year before their book came out) in a popular, widely read monthly, Century Magazine.  The article (“The Concealing Coloration of Animals”) and the book (Concealing Coloration in the Animal Kingdom) have all but identical titles, with the (possibly) inadvertent result that the article anticipates the book’s release.
In that article, the younger Thayer announces that he plans to dwell on the “two main results” of his father’s research. The first result was countershading, which we have discussed at length. The second is what Gerald calls “bold, contrasting patterns,” often brightly colored, even iridescent. When the actual book came out, they used the words “ruptive” and “secant” instead. Just as Abbott Thayer had become skilled at shading through drawing and painting, he was also well aware of the artistic importance of surface continuity and disruption. In particular, there is a passage (in a 1918 article) in which he talks about ruptive pattern effects in relation to artistic training:
“As all painters know,” writes Thayer,
two or more patterns on one thing tend to pass for so many separate things. All art schools will tell you that it takes a far-advanced pupil to be able to represent the patterns on any decorated object so true in degree of light and darkness as not to ‘cut to pieces’ the object itself, and destroy its reality. 
It was widely believed in 1908 (and to large extent still is) that while some animal coloration contributes to camouflage, other aspects function as conspicuous “display,” for purposes of sexual selection and warning coloration. In Gerald Thayer’s article, he (like his father) refutes this. He argues that all animal coloration, however conspicuous it is in “colorless collecting boxes or the plastered walls of a museum,” is designed to function as “concealing coloration” in the context of its own natural habitat. 
Unlike man-made indoor settings, he writes,
The real outdoor world is a boundlessly varied pageant of ever-shifting lights and forms and colors, cut up into innumerable bolder and dimmer patterns of all kinds and sizes, dancing and altering in endless, kaleidoscopic show with the play of wind and sun and clouds.
In brief, ruptive patterns work because “the bolder, brighter, and more arbitrary such a creature’s patterns are, the more they will cut up his own peculiar and characteristic form, and dissolve him into his background.”
In the Thayers’ book, one demonstration of ruptive patterns consists of a photograph of four butterfly shapes arranged on a middle-gray background. Three of the butterflies are monochrome (not unlike khaki field uniforms) in white, black, and a value of gray. The surface of the fourth butterfly is typical of the dazzling display on the wings of tropical butterflies. The caption beneath the photograph states that if that page of the book is viewed from a distance of
seven or eight yards in a bright light,” the reader will find “that all three of the monochrome butterflies, even the dimmest, can be seen further, or in a less illumination, than the normally and brightly patterned one. This latter fades first. 
At the time of the Spanish-American war, Thayer and his longtime friend, the painter George de Forest Brush (and later also Brush’s son, Gerome), had toyed with the idea of proposing military applications of protective coloration (it was not known as “camouflage” until 1914). As mentioned earlier, they experimented with the use of countershading on ships, but the Spanish-American war ended after several months, and their proposal to the US government went nowhere. At some point prior to World War I, Thayer turned to experiments using ruptive patterns for marine camouflage, as is shown by his drawings and paintings of ships, arranged and colored in a way that closely resembles his earlier butterfly experiments.  On occasion they used the word “dazzle,” but at first they did not recommend the use of ruptive patterns for ship camouflage—in fact, “my father,” Gerald Thayer writes, “did his utmost to dissuade the governments concerned from any and all such attempts.” 
Related to these were Abbott Thayer’s attempts to improve the function of field service uniforms (the outfits issued to foot soldiers). After World War I began (although the US had not yet entered the war), he appealed to the British Army command to replace their monochrome uniforms with ones that were multi-colored and ruptive. To demonstrate this, he devised a series of small diorama backdrops—painted simulations of landscape settings—on which he then overlayed painted cut-out figures of soldiers, in multi-colored ruptive clothes. 
As another demonstration of this, Thayer used an old Norfolk hunting jacket that had belonged to William James, given to him when the philosopher died by James’ sons, Billy and Alec, who were painters
and students of Thayer. To show how ruptive patterns work, Thayer attached to it a hodgepodge mix of scraps of cloth. When a photograph of this outfit was published in news reports in 1918, the person shown was said to be a “British sniper” or a “camouflage scout,” but in fact the model was Thayer himself. 
There is a third corollary in Thayer’s understanding of animal coloration that is a greater challenge
to grasp than countershading and disruption. It is difficult to explain, and neither he nor Gerald did very well in defining it. They even had difficulty naming it, so that when their book came out, the concept was confusingly called “background picturing.”
That term was unfortunate, because it made it sound as if an animal’s appearance results in a literal “picture,” a pictorial representation of a single, particular setting, as the Thayers seem to suggest when they refer to it as “a picture of such background as would be seen through it if it were transparent.” But a few sentences later, it becomes evident that they mean not a picture per se but a generalized abstract pattern that functions as “a sort of compound picture of their normal backgrounds—a picture seemingly made up by the averaging of innumerable landscapes.” 
In an essay on “Camouflage in Nature and in War,” written in 1919, two years before his father’s death, but not published until 1923 (perhaps because he dared to doubt his father’s “extreme” views), Gerald makes another attempt to explain what background picturing is. But this time he gives it the alternate name of “picture-pattern,” by which he “means a pattern which pictures, or imitates, the pattern of the object’s background.” 
The complexity of this idea is suggested by a number of illustrations in their book, one of which is a drawing of a bird within a setting of a “uniformly patterned horizontal ground plane” as viewed by an observer who is looking (slightly) downward.  The intention is to show how the animal’s markings abstractly yet persuasively rhyme with the perspective pattern of the ground.
An even more striking example is a small but remarkable painting by Gerald Thayer of a Male Ruffed Grouse in the Forest.  The younger Thayer’s masterpiece is an artful confirmation (and, in some ways, a grand deception itself) of all three of his father’s ideas about the inner workings of camouflage: countershading, figure disruption, and background picturing.
In that painting, a grouse stands frozen in the woods. Its body is exquisitely countershaded, its surface deftly broken up by contrasting ruptive markings, which conveniently coincide with the sizes and angles of similar shapes in the wooded background. The bird’s overall coloring and the twig- and leaf- and bark-like shapes that encase its patchwork body are precisely applied to result in—Voila!—another astonishing vanishing act.
1. For more on countershading, see M. Stevens and S. Merilata, eds., Animal Camouflage (UK: Cambridge University Press, 2011).
2. See E.R. Kandel, The Age of Insight (NY: Random House, 2012), 267-269.
3. “Out-of-Door Studies: Mr. Abbott H. Thayer, the Painter, on the Colors of Birds,” Boston Evening Transcript, January 30, 1897.
4. G.H. Thayer, Concealing Coloration in the Animal Kingdom (NY: Macmillan, 1909). Full text and illustrations can be accessed at https://archive.org/details/cu31924022546406.
5. Ibid., 24.
6. A.A. Allen, “Concealing Coloration of Birds,” Bird Lore (National Audubon Society, 1921), 321.
7. N. White, Abbott H. Thayer: Painter and Naturalist (Hartford CT: Connecticut Printers, 1951), 12.
8. N.D. Bowditch, George de Forest Brush (Peterborough, NH: Bauhan, 1970), 151.
9. A. Post, ed., Abbott Handerson Thayer: A Beautiful Law of Nature, Exhibition catalog (Washington, DC: Gold Leaf Studios, 2014), 50.
10. E.B. Titchener, “A Thayer Tiger,” American Journal of Psychology 25, no. 2
(April 1914): 296-297.
11. F. Heider, “Gestalt Theory: Early History and Reminiscences” in Historical Conceptions of Psychology, ed. M. Henle, (New York: Springer, 1973).
12. G.H. Thayer, “The Concealing Coloration of Animals,” Century Magazine (May 1908), 249-261.
13. A.H. Thayer, “Camouflage,” Scientific Monthly (December 1918), 488.
14. G.H. Thayer, “The Concealing Coloration of Animals,” 256.
15. G.H. Thayer, Concealing Coloration in the Animal Kingdom, precedes 153.
16. A. Post, Abbott Handerson Thayer, 58.
17. G.H. Thayer, “Camouflage in Nature and in War,” Brooklyn Museum Quarterly 10 (1923): 165.
18. A. Post, Abbott Handerson Thayer, 46-50.
19. R.R. Behrens, ed., Ship Shape: A Dazzle Camouflage Sourcebook (Dysart, IA: Bobolink Books, 2012), 36.
20. G.H. Thayer, Concealing Coloration in the Animal Kingdom, 31.
21. G.H. Thayer (1923), 159.
22. G.H. Thayer, Concealing Coloration in the Animal Kingdom, facing 32.
23. The painting is reproduced in color in G.H. Thayer, Concealing Coloration in the Animal Kingdom, facing 38.
Designer and author Roy R. Behrens is Professor of Art and Distinguished Scholar at the University of Northern Iowa. He has published seven books, hundreds of journal and magazine articles, and has been interviewed on PBS, NPR, BBC, Australian Public Radio, and in documentary films.