'Is Google Making Us Stupid?' was the provocative title of a recent article in the US journal The Atlantic. Its author was Nicholas Carr, a prominent blogger and one of the internet's more distinguished contrarians. 'Over the past few years,' he writes, 'I've had an uncomfortable sense that someone, or something, has been tinkering with my brain, remapping the neural circuitry, reprogramming the memory. My mind isn't going - so far as I can tell - but it's changing. I'm not thinking the way I used to think.'

He feels this most strongly, he says, when he's reading. 'Immersing myself in a book or a lengthy article used to be easy. My mind would get caught up in the narrative or the turns of the argument, and I'd spend hours strolling through long stretches of prose. That's rarely the case any more. Now my concentration often starts to drift after two or three pages. I get fidgety, lose the thread, begin looking for something else to do. I feel as if I'm always dragging my wayward brain back to the text. The deep reading that used to come naturally has become a struggle.'

His diagnosis is that he's been spending too much time online. His complaint is not really against Google - it's against the network as a whole. 'What the net seems to be doing,' he writes, 'is chipping away my capacity for concentration and contemplation. My mind now expects to take in information the way the net distributes it: in a swiftly moving stream of particles. Once I was a scuba diver in the sea of words. Now I zip along the surface like a guy on a Jet Ski.'

To judge from the volume of commentary that has followed his article, Carr has touched a nerve. He was 'flooded with emails and blog posts from people saying that my struggles with deep reading and concentration mirror their own experiences'. Various über-bloggers such as Andrew Sullivan, Jon Udell and Bill Thompson took up the theme, adding their own twists. And prominent newspaper columnists such as Leonard Pitts (Miami Herald) and Margaret Wente (Toronto Globe & Mail) also revealed their private fears that addiction to cyberspace, and online media generally were, in fact, rotting their brains.

What's surprising in a way is that people should be surprised by this. The web, after all, was designed by a chap (Tim Berners-Lee) who was motivated to do it because he had a poor memory for some things. Add powerful search engines to what he created and you effectively have a global memory-prosthesis. Who won the Ascot Gold Cup in 1904? Google will find it in a flash - and remind you that the race that year was run on 16 June, which is also the day in which all the action takes place in James Joyce's Ulysses. What was the name of Joyce's father? A quick Google search turns up the DNB entry, which reveals all. And what was the name of the woman who proved to be Parnell's downfall? Ah yes, here it is: Kitty O'Shea... and so it goes on.

The combination of powerful search facilities with the web's facilitation of associative linking is what is eroding Carr's powers of concentration. It implicitly assigns an ever-decreasing priority to the ability to remember things in favour of the ability to search efficiently. And Carr is not the first to bemoan this development. In 1994, for example, Sven Birkerts published The Gutenberg Elegies with the subtitle The Fate of Reading in an Electronic Age, a passionate defence of reading and print culture and an attack on electronic media, including the internet. 'What is the place of reading, and of the reading sensibility, in our culture as it has become?' he asked. His answer, in a word, was 'shrinking' due to the penetration of electronic media into every level and moment of our lives.

But people have worried about this since... well... the Greeks. In the Phaedrus, Socrates tells how the Egyptian god Theuth tried to sell his invention - writing - to King Thamus as 'an accomplishment which will improve both the wisdom and the memory of the Egyptians. I have discovered a sure receipt [recipe] for memory and wisdom.' To which the shrewd old king replied that 'the discoverer of an art is not the best judge of the good or harm which will accrue to those who practise it... Those who acquire writing will cease to exercise their memory and become forgetful... What you have discovered is a receipt for recollection, not for memory.'

In other words, technology giveth; and technology taketh away. Now, who was it who said that...?

john.naughton@observer.co.uk