Dazzle Camouflage Affects Speed Perception

Abstract

Movement is the enemy of camouflage: most attempts at concealment are disrupted by motion of the target. Faced with this problem, navies in both World Wars in the twentieth century painted their warships with high contrast geometric patterns: so-called “dazzle camouflage”. Rather than attempting to hide individual units, it was claimed that this patterning would disrupt the perception of their range, heading, size, shape and speed, and hence reduce losses from, in particular, torpedo attacks by submarines. Similar arguments had been advanced earlier for biological camouflage. Whilst there are good reasons to believe that most of these perceptual distortions may have occurred, there is no evidence for the last claim: changing perceived speed. Here we show that dazzle patterns can distort speed perception, and that this effect is greatest at high speeds. The effect should obtain in predators launching ballistic attacks against rapidly moving prey, or modern, low-tech battlefields where handheld weapons are fired from short ranges against moving vehicles. In the latter case, we demonstrate that in a typical situation involving an RPG7 attack on a Land Rover the reduction in perceived speed is sufficient to make the grenade miss where it was aimed by about a metre, which could be the difference between survival or not for the occupants of the vehicle.

The function of zebra stripes

“…Functional hypotheses fall into five broad categories: a form of crypsis probably matching a woodland background, disrupting predatory attack, reducing thermal load, having a social function and avoiding ectoparasite attack [5][6][7] . Only two have received more than passing attention: humans find moving striped objects difficult to target accurately on a computer screen, suggesting a possible motion dazzle confusion effect [8][9][10] , and tsetse flies, stomoxys stable flies and tabanid biting flies are less likely to land on black and white striped than on uniform surfaces [11][12][13][14] .…”

Shape recognition for ships: World War I naval camouflage under the magnifying glass

“…Recent research in the domains of zoology and perceptual psychology indicates some relevant effects of disruptive camouflage on shape interpretation and speed estimation [12,13]. Those experiments rely on human observation of computer generated animations and images.…”

Motion dazzle: a locust's eye view

“…Motion dazzle describes high-contrast patterns that do not conceal an object, but interfere with an observer's perception of its motion [1][2][3][4]. The only experimental evidence for motion dazzle is from studies of humans completing computer-simulated target-capture or speed-judgement tasks, with limited consensus among results [1][2][3][4].…”

“…One possibility is that this results from cross-pathway inhibition between separate ON and OFF channels that converge to form the excitatory inputs to the LGMD [8,9]. As patterns that dazzle humans contain high-contrast edges which would elicit ON and OFF stimuli during movement [1][2][3], I extend the early DCMD experiments to ask whether antagonistic interactions between ON and OFF stimuli provide a substrate for motion dazzle in the locust visual system.…”