Bill Thompson considers how our multi-media world is impacted the way we see ourselves.
In her recently published book ID: The Quest for Identity in the 21st Century, Professor Susan Greenfield brings her considerable expertise as a neuroscientist to bear on the question of whether and how our current use of computers is changing the way our brains work.
Greenfield argues that the visual stimulus we get from screen-based information and entertainment differs so markedly from that available to previous generations that certain areas of the brain, specifically those areas that are older in evolutionary terms and retain the capacity to alter as a result of experience, may be affected in ways that express themselves a changes to personality and behaviour.
It's an interesting hypothesis, and one that has the virtue of being experimentally testable, unlike many other claims about the effect of modern living on human psychology.
And it is a model that Nick Carr uses to support his rather broader viewpoint that our intellectual faculties are being damaged by the internet in his latest essay for the US-based Atlantic magazine.
Carr believes that the style of searching and exploration of links encouraged by search engines such as Google is changing the way heavy users think, reflecting that "over the past few years 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".
War and Peace
He likens himself to HAL, the computer in Arthur C Clarke's 2001: A Space Odyssey, reverting to child-like singing as its memory banks are disconnected by astronaut Dave Bowman.
He regretfully notes that "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".
Although the piece has the attention-grabbing headline 'Is Google Making Us Stupid?' Carr's target is really the whole internet, where Facebook status updates and invitations compete with incoming Twitter posts, Friendfeed alerts and RSS feeds from hundreds of websites to overwhelm any attempt to pay careful attention to a well-ordered argument spread over thousands of words or hundreds of pages in a linear fashion.
Why read War and Peace, he seems to say, when you can get a text message from a friend to tell you what has happened to Pierre in only 160 characters, or cut it down to 140 for Twitter?
It's a nice argument, and has succeeded in provoking a wide-ranging debate.
John Battelle, for example, sees himself getting cleverer as he searches, follows links and absorbs information, arguing that when "performing bricolage in real time over the course of hours, I am 'feeling' my brain light up, I and 'feeling' like I'm getting smarter. A lot smarter, and in a way that only a human can be smarter".
Battelle may feel smarter, but he also accepts that the way of working online is different from that which prevailed when we were a print-based culture. He just thinks it is at least equal, if not superior, to what went before.
There does seem to be a difference between screen-based literacy and page-based literacy, and the reason may be that outlined by another participant in the debate, developmental psychologist Maryanne Wolf.
In her new book, Proust and the Squid: The Story and Science of the Reading Brain, she points out that reading is not an innate ability for humans but something we have to learn how to do, and there is no reason why different forms of literacy should not emerge as new technologies do.
After all, the ability to read a text is as much a learned behaviour as knowing how to use a mouse to control a cursor on screen, and it is claimed that the Venerable Bede, the monk who lived in Jarrow in the seventh century, was the first person to read without moving his lips.
Whether or not our brains are being fundamentally altered by the products of the Googleplex it is clear that the current generation of search tools are changing the ways we look for information and the navigational strategies we use to find our way from source to source, looking for data and insights.
Today's internet presents information in bite-sized chunks, linked together into a rich tapestry where the connections often carry as much meaning as the words themselves.
The fact that a blog post recommended by one of the A-list bloggers may matter more than what it says; and often the accumulation of small references to a topic is vital to build up our understanding.
The impact does not have to reflect a change to neuroanatomy or a fundamental shift in our way of engaging with the world of words. It could just be that search engines, RSS feeds and Tweets are western culture's informational drug of choice, the intellectual equivalent of LSD in the 60's, cocaine in the 80's and ecstasy in the 90's, a temporary obsession.
Google and other search engines may satisfy us because they are less likely to take us into areas where our preconceptions are challenged.
One of the reasons I like my Twitter friends is that I've chosen to follow people I like, whose views and opinions I am more likely to find acceptable. If I am challenged by them then it is within severely proscribed limits - I'm not following Fox News, for example, because I'd just find it annoying.
The Swiss developmental psychologist Jean Piaget described two processes that he believed lay behind the development of knowledge in children.
The first is assimilation, where new knowledge fits into existing conceptual frameworks. More challenging is accommodation, where the framework itself is modified to include the new information.
The current generation of 'search engines' seem to encourage a model of exploration that is disposed towards assimilative learning, finding sources, references and documents which can be slotted into existing frameworks, rather than providing material for deeper contemplation of the sort that could provoke accommodation and the extension, revision or even abandonment of views, opinions or even whole belief systems.
Perhaps the real danger posed by screen-based technologies is not that they are rewiring our brains but that the collection of search engines, news feeds and social tools encourages us to link to, follow and read only that which we can easily assimilate.
Time to start following Fox, I think, and take myself out of my online comfort zone.
Bill Thompson is an independent journalist and regular commentator on the BBC World Service programme Digital Planet.