Colour illusions

Some visual illusions, such as after-images and black and white spinning discs, are thought to be the result of this colour vision mechanism.

Other illusions can result from the way in which the brain interprets the signals received from the eyes. This is the origin of the 'Mach Band Effect' and contrasting colour illusions. Our brains emphasise colour differences and the boundaries between colours.

Coloured and black and white patterns can be used to produce visual illusions which can help us to understand how we see colour and how our brain makes sense of the world around us.

Illusions can result from effects produced in the retina at the back of the eye. Although there is some disagreement about how we see colour, it is generally accepted that our retinas have different receptors which are predominantly sensitive to red, green or blue light. When white light enters the eye, all three types of receptor are triggered, resulting in the sensation of 'white'.