Andrew Hanson was a scientist at the National Physical Laboratory measuring colour for 22 years. He was Chair of the Colour Group of Great Britain 2009-2011, and has built a machine to measure the shininess of cats. In his talk he burns images into the audience's eyes and convinces them that, for a while at least, they are simultaneously understanding the complexities of additive and subtractive colour, and that pink elephants live and fly around the room. One of these effects is more persistent than the other.

In the spirit of ideas worth spreading, TEDx is a program of local, self-organized events that bring people together to share a TED-like experience. At a TEDx event, TEDTalks video and live speakers combine to spark deep discussion and connection in a small group. These local, self-organized events are branded TEDx, where x = independently organized TED event. The TED Conference provides general guidance for the TEDx program, but individual TEDx events are self-organized.* (*Subject to certain rules and regulations)