Rory Cellan-Jones has a less interesting but more...well, more BBC, take on the same subject here.
I guess they're both prompted by The Shallows by Nicholas Carr - a man with whose previous writings I have disagreed violently. Looks like the subtitle on the paperback has quietly been changed from "What the Internet is doing to our brains" to "How the Internet is changing the way we think, read and remember". Presumably the old title was provoking too much hostility.
Carr's thesis about shallow thinking is very different to, say, Tyler Cowen's Age of the Infovore, which argues that the Internet now allows us a much deeper and more engaged experience with the narratives of our lives.
Rory's argument (and that of Douglas Adams, to whom Henri links) is that this debate has been going on for millennia and that the cognitive changes are not in the direction Carr thinks. In fact, new media are more interactive and more creative than old-fashioned TV, radio and newspapers.
Hen's argument is more subtle. Each step in the evolution of media reveals something new about how we pay attention. Multitasking can work for some media - background radio music occupies little enough attention that we can still work (though see Peopleware for caveats); TV (and adverts in particular) move us to context-switching instead of multitasking; modern fragmented low-latency communication reminds us that deep thinking is not very natural to us.
Indeed, there's an economic argument about deep thinking which is a little like the argument I'm making in another blog post, still in draft mode (like most of them right now, sorry - will link to it when ready). Deep thinking is not really in our own interest. Shallow thinking - working out what tactical manoeuvre to try next, who you can trust and who to copy from, and simply impulsively satisfying yourself with whatever nuggets are available - will bring you a much easier and more fun life, and more quickly.
Deep thinking, on the contrary, is hard work, takes ages, might fail, and mainly benefits other people. If I discover the new theory of everything which reveals the purpose of the cosmos, what do I get? Sure, I'll probably make some money - at least Malcolm Gladwell's publishers will offer me a contract - but the rest of the world benefits much more than me.
Economics provides a simple explanation for this - deep thinking has a big positive externality. If we want people to think more - and we do, because it's good for human progress - we need to compensate them for it. Society should pay the people whose thinking fails as well as those who succeed. It should provide thinking-friendly environments - which provide a mix of different people from different disciplines to talk to each other...in a kind of "universal" knowledge blend...you might even call them "universities".
But don't make it holy. As soon as we start telling people which kind of thinking is best - well, you know where that leads. Diversity in all things should be our watchword - and in cognition too.