London taxi drivers' "Knowledge" shows up clearly as an enlarged hippocampus (concerned with memory) in the brain. Similar results are found in anyone who practises difficult mental feats such as playing music, learning foreign languages, performing complex maths operations. The rule for all bodily functions, especially nerve and muscle functions, is: "use it or lose it". But The Knowledge and playing Bach fugues are clearly "good" brain activities that reinforce patterns that lead to better performance. What's the problem with digital media?
That's the question Susan Greenfield, neuroscientist, writer and broadcaster, sets out to answer in Mind Change. Does the habitual and apparently sometimes addictive use of digital media have a physical impact on the brain? It would be very strange if it didn't. The obvious difference between acquiring The Knowledge, or any knowledge, old-style, is that all traditional learning tasks require slow, sustained work on material that yields its rewards, with difficulty, in an orderly fashion. When you are playing a piece from a score, distracting passages are not constantly intruding. But when you open something online, everything else is only a few clicks away. As Greenfield says, in pre-digital activities there was always a linear sequence; this is no longer true – the hyperlink destroyed that.
When there is no hard scientific evidence available, Greenfield employs common sense; much of what she says seems obvious, although it's sometimes clothed in obscurantist language: "Your identity is therefore a spatio-temporal phenomenon..." Yes, we exist in space and time – we got that. At times, her concerns for the younger generation lead her into unconvincing advocacy. A smartphone-toting teenager is not going to be very impressed by her endorsement of Enid Byton stories "where the young heroes and heroines were so busy catching smugglers and other villains that they only ever went indoors at mealtimes and to sleep". As it is, computer gamers are developing skills that may one day make them very good drone pilots: a job far removed from anything envisaged in Blyton's world.
Greenfield cites many studies, often with inconclusive or contradictory results; nevertheless there are some startling statistics in this book. According to the UK law firm Divorce Online, Facebook was implicated in 33 per cent of marriage breakups in 2011, which makes it the greatest serial co-respondent of all time. It is the speed of change that is unnerving – Facebook went from start-up to marriage breaker in seven years. Whether it is a reliance on Google and Wikipedia instead of memory; SatNav or Waze instead of maps; online dating instead of meeting socially; the entire world's music available onstream instead of being slowly and expensively acquired – the digital world challenges all our age-old mental processes.
The importance of Mind Change's subject is clear but the book is hard to digest: with pros and cons batted back and forth and hedged about with caveats, there are times when you are almost driven to video games for relief. Strangely, although it's clear from statistics and her commentary that Greenfield is deeply worried about the effects of digital technology on the human psyche she says nothing about the currently fashionable attempt to counter it: mindfulness. Espoused by IT giants such as Twitter, mindfulness is a 21st century update of meditation derived from Buddhism. For most of us, there's a middle way between narcotic thumb-twiddling and zoned-out contemplation.