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Wartime recruiting poster for the Decima Flottiglia MAS ('10th Assault Vehicle Flotilla'). 'La Decima' was an Italian commando frogman unit of the Regia Marina (Italian Royal Navy), which was created under the Fascist regime. [Image: Wikipedia.]
Military applications of crypsis
Many of the armies that went to war in 1914 boasted colourful uniforms, which served to distinguish friend from foe. However, the First World War soon taught that drab uniforms were much better suited to the conditions of modern warfare, under which concealment became just as important to survival as identification ever was.
Under these conditions, the uniform colours worn by German riflemen and British soldiers — Feldgrau ('field-grey') and khaki, respectively — were, clearly, the most satisfactory. These dull, neutral colours blended the colours that predominated in a wide range of wartime environments; and so, more by luck than by design, they functioned as simple forms of mimetic camouflage.
So far as camouflage goes, though, these solid colours were not unqualified successes. Since their concealing effect was due more to luck than to design, Feldgrau and khaki uniforms failed to take into account the fact that the human visual system comprises two distinct components: focal vision (also known as foveal vision) and ambient vision (also known as peripheral vision).
Focal vision and ambient vision
Ambient vision is often referred to as peripheral vision. It comprises the visual functions that are associated with the maintenance of spatial orientation and depends on preconscious visual input. For example, you can fully occupy yourself with reading a book or magazine — a conscious activity — and still receive sufficient cues, through peripheral vision, to walk — a preconscious activity — without too much risk of collision.
If you've ever been startled by a movement seen 'out of the corner of your eye', then you've experienced this aspect of human visual perception. This is because colour is not a factor in the operation of ambient vision, but movement and contrast are. The drab Feldgrau and khaki uniforms that were worn during World War I reduced the visual contrast between soldiers and the predominantly dull colours of their surrounding environment; therefore, they worked against the ambient visual system.
When seen head-on, however, a soldier clad in Feldgrau or khaki is still recognisably a soldier, no matter what their background might be. This is because solid colours are not so effective against the focal visual system.
Focal vision is limited to the central two degrees of the visual cone and is primarily a conscious function. Relying on conscious visual input, it allows you to see clearly, in order to recognise objects, and colour plays a major role in its operation.
Imagine a stack of 16 blocks. If all of them are red, then you can easily see the square. If the top eight blocks are red and the bottom eight blocks are blue, however, you probably see two separate rectangles before you recognise the square. And if you were to mix the red and blue blocks together, you probably wouldn't describe them as a single square at all.
Disruptive camouflage, on the other hand, aims to break up the animal's body shape and outline. Many animals have evolved distinctive patterns, which conceal them, because it is a very effective adaptation. It is also a very economical one, since it usually involves only colour and pattern.
One simple type of disruptive camouflage is countershading, which defeats a predator's ability to identify prey by shape. In countershading, the upper parts of an animal are dark and its lower parts are light. This reverses the normal distribution of luminance on objects, which are usually lit from above. The predator's eye is drawn to the lighter areas and, since the brain interprets the contrast between light and dark as a natural boundary, it is discouraged from 'putting together' the two areas and perceiving a single object.
Many animals display even more elaborate patterns of contrasting patches, spots or stripes. A zebra's stripes, for example, are so striking a design that it is difficult to imagine how they could possibly function as camouflage; after all, black and white are not colours often seen in the environment. Nonetheless, zoologists believe that these stripes serve to conceal zebras from predators in at least two different ways.
One thing your brain is always looking for, when analysing visual information, is continuity. For example, you tend to recognise something as a single object if it has a single, continuous colour; so, a person is much more likely to 'stand out' from their background and be recognised as a human being if they are wearing a single, solid color than they are if they are wearing a variety of colours. This concept is demonstrated by the three boxes, illustrated to the right of this paragraph. In this demonstration, you see the 16 red boxes as a single square; but you perceive the same square differently, when two colours are used in different combinations.
The dazzle camouflage paint schemes, which were used primarily on ships during World War I, were probably the first considered attempt to thwart the focal visual system.
Dazzle camouflage
Dazzle camouflage consists of complex geometric patterns, painted in contrasting colours. Its purpose was to disrupt the performance of the visual rangefinders. [Image: Roger & Martyn Dean.]
The invention of dazzle camouflage is most often credited to artist Norman Wilkinson, who served with the British Royal Navy during World War I. The scheme consists of complex geometric patterns, painted in contrasting colours, which interrupt and intersect each other. Like a zebra's stripes, it might seem an unlikely form of camouflage, at first, since the colours tend to draw attention to the ship rather than hide it.
However, dazzle camouflage had a very specific purpose, which was to disrupt the performance of the visual rangefinders that were in use, at the time. These rangefinders used optics, mechanics and a human operator to compute the range to the target. The operator's job was to adjust the mechanism until two half-images of the target aligned, to form a complete picture. Dazzle camouflage was intended to make this job more difficult, inasmuch as the clashing patterns wouldn't look 'right', even when the two half-images were correctly aligned.
Even during the First World War, the effectiveness of dazzle camouflage was debated. The British concluded that it had no material effect on submarine attacks, but nonetheless proved a morale boost for crews. The Americans, on the other hand, felt that dazzle camouflage was effective.
Effective or not, dazzle camouflage continued to be used until World War II. More significant, though, was its influence on the development of the first standardised and widely issued military camouflage pattern — German Buntfarbenaufdruck.
Copyright © 2005, 2008 Brad Turner. All rights reserved.