The late Professor Richard Gregory introduces the science of illusions
Walking past this café in Bristol, Professor Richard Gregory and members of his lab spotted this illusion created by the tiling. After several months of theories, discussion and the building of interactive models, they had understood how our visual systems create the café wall illusion.
This illusion comes about because the black and white rectangles do not sit directly above one another. You clearly see the horizontal grey space between the black and the black, and accentuate this difference. However, the horizontal grey between the white and the black rectangles is not so clear. Your visual system decides this space is not real, so shrinks it. This has the effect of producing lots of wedges, which your brain puts together and decides you are looking at non-parallel wavy lines.
Try this simpler view of the illusion.
Professor Richard Gregory was a leading expert on illusions and was based at Bristol University. He spent over 50 years investigating how our eyes and brain work together to perceive the world around us.
He was perhaps best known for his work on the Cafe wall illusion.