It's difficult to see what's wrong with this image until you turn it the right way round. For the 2011 Royal Institution Christmas Lectures, Prof Brian Cox very kindly agreed to let us use his face for the classic inverted face illusion. The Ri is on Twitter: http://twitter.com/ri_science and Facebook: http://www.facebook.com/royalinstitution and Tumblr: http://ri-science.tumblr.com/ Our editorial policy: http://www.rigb.org/home/editorial-policy Subscribe for the latest science videos: http://bit.ly/RiNewsletter