In today's plugged in, online, information‑saturated world, it's good to be a skilled multi‑tasker, right?  Unless you're able to "tweet", chat, and update your Facebook status all at the same time, you're sure to fall behind the curve.

Or maybe not

According to  one study, habitual multi‑taskers actually have trouble concentrating on more than one thing at once. The researchers, at Stanford, studied about one-hundred multi‑tasking students to see how well they performed on simple tests.

For example, identifying pairs of letters flashing on a computer screen and recognizing a letter that was the same as one shown two or three letters earlier.

Now, you might assume that students used to habitual multi‑tasking would be good at this.  But you'd be wrong.  The researchers found that the heavy multi‑taskers were also the most easily distracted.

They actually had a harder time carrying out simple letter identification tasks than lighter multi‑taskers.  Chronic multi‑taskers were also slower at switching between tasks.

So what does this mean?

Well, it suggests that, at some basic level, the human brain isn't really wired for multi‑tasking. Generally speaking, we're better able to concentrate on one thing at a time.

Other studies have come to similar conclusions--like ones showing that talking on a cell phone or texting while driving are great ways to up the likelihood of getting in an accident.

As for why multi‑tasking is so prominent and even encouraged at work and in school--that will require further study.