by Matthew Cobb
This popped in my tw*tter feed – RT’d by one of my lecturers from 40 years ago, Graham Davey…
I had to stare at this very hard to be sure it was an illusion. Science blogger and lecturer in Psychology, @PeteEtchells, pointed out that it’s a version of the Café Wall illusion. (If you remove the horizontal lines from the graph above, with the exception of the X-axis, you’ll destroy the effect). The illusion was named by the late, great, Richard Gregory, whose book, Eye and Brain is a must-read for anyone interested in such things. (One of my fellow psychology students at Sheffield in the 1970s wrote a whole essay about Gregory’s work, referring to it throughout as ‘Iron Brain’. I guess he hadn’t actually read it…)
Pete pointed my to the relevant Wiki page, which includes this great picture of Gregory next to the original cafe wall where he noticed the effect. This was taken on St Michael’s Hill in Bristol, in February 2010. Gregory died three months later.