Motion camouflage : does pattern configuration interfere with object tracking?

A resurgence in camouflage studies has begun to define the many facets of camouflage. The majority of this work has used stationary objects, but it is likely, considering the constant dynamic state of the natural world, that some patterns have been selected for their interaction with motion. In this...

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Bibliographic Details
Main Author: Watkins, Scott
Published: University of Bristol 2012
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Online Access:http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.573158
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Summary:A resurgence in camouflage studies has begun to define the many facets of camouflage. The majority of this work has used stationary objects, but it is likely, considering the constant dynamic state of the natural world, that some patterns have been selected for their interaction with motion. In this sense, an animal whose pattern makes it difficult to accurately track, termed motion disruption, may benefit from increased survival. It has been suggested that certain contrast and pattern orientations can cause the visual system to make small speed and trajectory errors when viewing a moving target, but the evidence for this is sparse and generally only demonstrated under strict conditions using Gaussian stimuli on plain backgrounds. Using 3D modeling and animation software, I first designed a study to look at contrast and stripe orientation in zebra fish. The experiment used a two forced choice paradigm and measured response time and accuracy to identifying a smaller target fish in order to determine whether patterns benefit survival within a shoal. Two further experiments used similar patterns with the first applied to a moving vehicle viewed from a tangential perspective and the second applied to an approaching motorcycle on a longitudinal path. These experiments measured time-to-contact, requiring the viewer to predict the location of the moving target whilst measuring the miss distance and comparing results over a number of different variables. Throughout the three experiments, pattern was demonstrated to provide a degree of motion camouflage to the target, causing longer response times and lower accuracy than plain targets. It is suggested that the mechanisms functioning for these advantages differ between patterns and experiments. The current experiments, add weight to the literature that suggests certain pattern configurations can enhance the survivability of targeted objects, by causing illusions in the predators visual system.