Why Multitasking Makes Us Stupid

03/15/2011 11:28 am ET Updated May 25, 2011

According to recent research by State Farm, twenty percent of drivers are now accessing the Internet while driving. This is just the latest example of dangerous multitasking in cars. We already talk on the phone - even though all the evidence shows that doing so puts us in as much danger as being over the legal alcohol limit. And car manufacturers, who seem to prefer giving us gadgets we don't want in preference to fuel economy that everyone needs, now boast of cars that offer wifi and USB ports.

It's madness of course. Our belief that somehow we can drive and talk, drive and surf, drive and text is just another form of willful blindness. Why? Because all of the scientific evidence shows that there are quite hard limits to our cognitive capacity. We cannot take in infinite amounts of information simultaneously and, when we try to, it's simple: we create a bottleneck and lose control over what gets in and what gets left behind.

That bottleneck also explains why, when we watch TV, we miss so much. All the scrolling text, side bars and stock prices don't make us smarter or better informed; they make us stupid. What we can't do while we are watching such a busy array is think, discriminate or make critical judgments. Because when assaulted by too much information, the first thing we lose is what we need most: critical thinking.

"Resource depletion specifically disables cognitive elaboration," says Harvard psychologist Daniel Gilbert [pdf]. "Not only does doubt seem to be the last to emerge, but it also seems to be the first to disappear."

In other words: because it takes less brain power to believe than to doubt, the busier we are -- the more gullible we become. Which may explain a lot about the state of politics and business these days....