CrowdScience listener Gregory wants to know what affects the way we see the colours of the world. He was looking at a blue summer sky with a friend and they got to wondering whether they both see the same colour blue. So what does influence our vision of the colours that surround us? Could eye colour have anything to do with it? And can we ever really know if your blue sky is the same as mine? Caroline Steel comes up with some answers, talking to colour scientists about their research into the multiple factors that enable us to see in multi colours, from the intricate biology of our eye to the changing environment around us. She also investigates her own colour vision and solves a personal mystery, discovering why the world has always looked a slightly different colour from each eye. Contributors: Professor Jay Neitz, Department of Opthalmology, University of Washington, US Professor Hannah Smithson, Department of Experimental Psychology, University of Oxford Dr Juan Perea García, researcher, Department of Cognitive Psychology, University of Leiden Dr Lauren Welbourne, researcher, Department of Psychology, University of York Dr Adam Bibbey, lecturer in sport, Department of Sport, Oxford Brookes University Presenter: Caroline Steel Producer: Jo Glanville Editor: Cathy Edwards Production co-ordinator: Connor Morgans Studio manager: Jackie Margerum (Photo: LWA)