Research debunks misconceptions around peripheral colour vision

Some common science-related misconceptions are particularly persistent, such as a duck’s quack doesn’t echo, or that we only use 10% of our brains.

Now new research from City University London is aiming to dispel a long-held misbelief relating to colour vision: that it is weak or non-existent in our periphery vision.

“This misconception about weak peripheral colour vision is completely incorrect,” said Professor Christopher Tyler, a visual neuroscientist at the university’s School of Optometry and Vision Science, who carried out the study.

“Although the number of cone photoreceptors is lower in the periphery than in the fovea, with about 4000 cones per mm² throughout the peripheral retina compared to 200,000 in the central fovea, this is still plenty enough to give colour vision,” said Professor Tyler.

The research challenges the idea that colour vision is restricted to the fovea, where the cone cells are most densely packed. Using arrays of multicoloured disks, the study demonstrates that cones occur in sufficient numbers at the peripheral retina to provide vivid colour vision.

Professor Tyler added: “Unlike traditional studies of peripheral colour processing, the coloured disks, or patches, are scaled with distance from the fovea. This is a critical factor, because peripheral regions of the visual field project to progressively smaller regions of the visual cortex in the brain. Therefore, to give the periphery an equal chance and to level the playing field for the assessment of peripheral visual function, stimuli must be scaled up in proportion to distance from the fovea, in order to stimulate equal regions everywhere in the visual cortex.”

The findings could potentially have implications in the use of colour in a real world setting, such as signs and visual displays. Professor Tyler told OT: “It could be helpful for highway or aircraft signage, knowing that colour is a useful attribute to distinguish among items of a complex display extending into the periphery, but that it would need to be large to be equally visible in the periphery.”

The researcher confirmed that he is currently carrying out extensive studies of the electrical activity of the eye and brain in response to full-field colour stimuli, as well as exploring how the various photopigment mechanisms respond to colour.

The research is published in the online journal i-Perception.

Image credit: Professor Christopher Tyler