11 year old Esther visualises days of the week in a kind of 3D structure. It’s something called ‘synaesthesia’ and she wants to know why it happens - and why other people don’t experience things the way she does.

Hannah Fry and Dara Ó Briain explore the vibrant and varied ways different people experience the world, from the man who tastes individual words - including all the stops of the tube - to the composer who sees music in shapes and colours.

And along the way, they figure out why Mozart is white wine while Beethoven is red.

Contributors:

Professor Julia Simner: Professor of Psychology,University of Sussex

Producer: Ilan Goodman