More than a decade ago the technology specialist, Nicholas Negroponte, pro­phesied the emergence of the Daily Me – a fully personalised newspaper. It would allow you to include topics that interest you and screen out those that bore or annoy you. If you wanted to focus on Iraq and tennis, or exclude Iran and golf, you could do that.

Many people now use the internet to create something like a Daily Me. This behaviour is reinforced by the rise of social networking forums, collaborative filtering and viral marketing. For politics, the phenomenon is especially important in campaigns. Candidates in the US presidential race can construct information cocoons in which readers are deluged with material that is, in their eyes, politically correct. Supporters of Hillary Clinton construct a Daily Me that includes her campaign’s perspective but offers nothing from Barack Obama, let alone Mitt Romney.