This year's Reith Lecturer is Vilayanur S Ramachandran, Director of the Centre for Brain and Cognition. He has lectured widely on art and visual perception of the brain and is Editor-in-chief of the Encyclopaedia of Human Behaviour. Professor Ramachandran's work has concentrated on investigating phenomena such as phantom limbs, anosognosia and anorexia nervosa. In his fourth Reith Lecture, Professor Ramachandran demonstrates experimentally that the phenomenon of synesthesia is a genuine sensory effect. For example, some people literally 'see' red every time they see the number 5 or green when they see 2.