The neuroscientist Daniel Levitin warns that rapidly switching between tasks on digital media damages our concentration.
He outlines his concern about the effects on the brain in his book The Organised Mind: Thinking Straight in the Age of Information Overload.
Levitin says each time we dispatch an email, we feel a sense of accomplishment, and our brain gets a dollop of reward hormones telling us we accomplished something.
When we look at a Twitter feed or Facebook update, we encounter something novel and feel more connected socially (in a kind of weird, impersonal cyber way) and get another dollop of reward hormones.
As Levitin puts it, it is the dumb, novelty-seeking portion of the brain that induces this feeling of pleasure, not the planning, scheduling, higher-level thought centres in the prefrontal cortex.
Levitin says the modern emphasis on multitasking effectively rewards the brain for losing focus and for constantly searching for external stimulation. To make matters worse, the prefrontal cortex has a novelty bias, meaning that its attention can be easily hijacked by something new - like the shiny objects we use to entice infants, puppies and kittens.
"The very brain region we need to rely on for staying on task is easily distracted. We answer the phone, look up something on the internet, check our email, send an SMS, and each of these things tweaks the novelty - seeking, reward-seeking centres of the brain... all to the detriment of our staying on task. It is the ultimate empty-caloried brain candy."
Levitin argues that instead of reaping the big rewards that come from sustained, focused effort, we instead reap empty rewards from completing a thousand little sugar-coated tasks.
The neuroscientist highlights research from the psychologist Glenn Wilson, who calls the phenomenon "infomania".
One of his studies found that just being in a situation where you are trying to concentrate on a task, and an email is sitting unread in your inbox, can reduce your effective IQ by 10 points. Wilson showed that the cognitive losses from this digital multitasking are even greater than the effects of smoking cannabis.
Levitin's findings seem to be confirmed by the latest international research in schools.
In recent years some Irish schools have placed great emphasis on new technology, encouraging pupils to use laptops and iPads. The use of new technology is heavily advertised in school brochures, but a recent report from the OECD show that it doesn't improve test scores. The OECD found there was "no appreciable improvements in student achievement in reading, mathematics or science in the countries that had invested heavily in ICT [Information and Communications Technology] for education".
The OECD's report found that increasing digital access in education without proper controls can lead to difficulties including "information overload".