True colours: a test to determine how animals see colour

Trained fish at The University of Queensland are helping researchers understand animal vision and factors behind the huge variation in colours between and among species. Ms Naomi Green and Dr Karen Cheney from the Queensland Brain Institute and the School of Biological Sciences have devised what they believe to be the most thorough test of vertebrate colour perception ever developed. It is based on the Ishihara colour blindness test , which uses numbers or letters embedded in a series of dots to distinguish what colours people can or cannot see. The researchers have trained triggerfish to find an odd-coloured spot in a field of spots, and to peck it for a food reward. Ms Green said the test was more efficient and accurate than previous tests and had the potential to be applied across a variety of species. "Traditionally we would test what colours animals see using a paired choice method, with a choice between a red and a grey square , having previously trained the animal to know the green square gives it food," she said. Researchers would then reduce the colour difference between the red and grey squares, testing the animal's ability to differentiate between the two.