As Socrates, Doug Engelbart and many others have noted, we shape our tools, then they shape us. Writing was a useful invention, but our memory has suffered from it. Calculators are handy tools, but my students are not so great at doing arithmetic in their heads.
Like any other medium, the Internet is changing our cognitive abilities. We remember fewer phone numbers now that we have smart phones and when online we read quickly, superficially and carelessly, focusing our attention on the upper left hand portion of the screen. Our attention spans have been reduced and there is evidence that multitasking is inefficient.
But, it is not all bad news. Anyone who has watched a child construct 3-D worlds in Mindcrafter knows that they are masters at storing mental models of complex structures and navigating through them. There have also been studies showing that video game players are faster at making some kinds of decisions than non-gamers. (I bet basketball point guards, baseball players and football quarterbacks are great video game players).
A team of researchers led by Adam Gazzaley at UC San Francisco has just published a study showing improved cognitive ability in older people after practicing with a specially designed video game called NeuroRacer.
Playing the game helped older people multitask by improving their working memory and sustained attention. As their skills increased, so did activity in the prefrontal cortex of the brain, which is associated with cognitive control, in a manner that correlated with improvements in sustained-attention tasks. Activity also increased in a neural network linking the prefrontal cortex with the back of the brain.
The study was published in Nature and you can hear a podcast on it here and see a video summary here.
Studies like this one strike me as rather "brittle" -- focused on narrow abilities from which it hard to generalize, but the research is just beginning.