Everyone has seen an optical illusion before – you know, is this a rabbit or a duck? – but not everyone knows how they work. Optical illusions should really be known as visual illusions, as they do play tricks with your mind, after all. And it’s these tricks that make M.C. Escher drawings look like never ending staircases, or a couple of faces look like a vase. Or is it a vase that looks a couple of faces? It’s difficult to tell. Whether you’re wearing contact lenses or not, optical illusions can be a bit of fun, or some serious art.
There are many different types of visual illusions. Some are to do with shape, others to do with colour, and there are a host of other illusions that relate to pictures, or size, or distance, or geometrics, or just sensory perception itself. Some illusions rely on voluntary eye movement to produce an illusion, whilst others rely on us to focus on a particular point of the image. Other illusions occur without any other stimuli other than the image itself.
Illusions happen because of the different cells and receptors of the eye perceive images and colours at different rates. This means that a “false” image is relayed to the brain. The eye only perceives a limited amount of visual information at any time, but the brain keeps constructing and reconstructing that information – this gives us the experience of sight. But because the brain is constantly processing a limited amount of information, if that information is distorted, or contains a certain combination of shapes, colours, or other stimuli, then it creates the experience of a visual illusion.
All complex stuff. But don’t fret: even if you’re wearing contact lenses, you’ll still be able to enjoy visual illusions like Magic Eye puzzles.