Marcus De Sautoy, mathematician and all round interesting person, tries to discover what his consciousness really is, his 'I' as he calls it. It was an excellent documentary, you should watch it later on iplayer. He undergoes various experiments. One of them is amazing, a scientist puts marcus in a cat scanner to see how the brain makes decisions. Marcus has a button in each hand and has to decide which to press. It turns out the neurones of his brain make the decision 6 seconds before the conscious part of his brain is aware of it and actually executes that decision. So the scientist is consciously aware of marcus' decision 6 seconds before marcus consciously makes it, lol.