Many animals, including some snakes, have a blotchy pattern of camouflage known as disruptive colouration. Sometimes there is a light or dark outline surrounding the different coloured blotches and the role of these has been a matter of debate. A new experiment from Abertay, undertaken in collaboration with Stirling University, has now shown that these enhanced edges actually matter far more than simply varying colours across an animal’s body.
The research found that when the boundaries between different patches have added light and dark steps between them, people find the snakes much harder to spot than snakes with identical patches of colour but no enhanced edge. The edges don’t simply mimic shadows, they can be light or dark, and even when all the shadows in the background are excluded; there is still an added advantage for having enhanced edges. The researchers used a huge 6m display screen and digitally created beds of leaves to hide snake shaped targets. The observers had to find the snakes in a carefully controlled set of experiments that varied their camouflage. It seems the addition of enhanced edges gives the viewer perceive depth, so the different coloured blotches appear at different heights upon a surface. This may help animals to hide in a background like a leafy woodland floor, but also it may slow the process of recognising the overall shape of the camouflaged target.This allows them to remain undetected and spring onto unsuspecting prey.
The researchers hope that by understanding the way that shapes can best be coloured to make them hard to see, better camouflage can be designed when it’s needed and that countermeasures to camouflage can also be developed. The precise nature of the best camouflage can be then developed to best mimic and break up the context.
The research team was led by Dr George Lovell from Abertay University and the work was undertaken by Student John Egan as part of his Masters degree in Psychology. John said: “When we found the experiment worked, we realized we had to do some additional experiments to verify this and then get the work out in published form as soon as possible. “This project has helped me get the experience I needed to get a PhD Place to pursue my passion of vision science.
Dr Lovell added: “Because we let our Masters student tackle problems they choose, John was able to approach the research area with his own ideas, develop his research question and collect the data all for his own degree project. “Overall it was a great team effort with us all collaborating electronically from wherever we were in Asia, Europe or the US at the time. “We could not have done the work without the laboratory and the online collaboration tools we now take for granted.”
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