Can you think of 100 different uses for a sock? How would you cope with glasses that turn everything upside down? What's your emotional intelligence? Can you create a work of art in 10 minutes? Horizon takes seven people who are some of the highest flayers in their field: a musical prodigy, a quantum physicist, an artist, a dramatist, an RAF fighter pilot, a chess grandmaster and a Wall Street trader, and puts them through a battery of tests to measure their intelligence. Who is the most intelligent? The principle way that we measure intelligence, the IQ test, is based on research done before even Einstein was in his prime. Because these tests label us with a single number they are still a popular and convenient way to divide people into clever clogs and dunces. But most psychologists agree that they only tell half the story, at most. Where they disagree is how we measure intelligence, for the very good reason that they still don't know exactly what it is. Horizon looks for evidence of intelligence in the brain, in our genes and in our upbringing and tests some of the latest theories using them to see which of the seven has the highest intelligence. Wall Street Trader, Nathan Hasselbauer has an IQ of 167, but is he creative? Artist Stella Vine left school at 13 how would she know the distance from London to Hong Kong? Dramatist and critic Bonnie Greer has got a great vocabulary, but what's she like at inductive logic?