Plenty of folks say they’re great multi-taskers. Listen to the professor while texting? No problem, they say.  Drive and talk on the phone?  No biggie.

But, unfortunately for those who brag about their natural talent to pay attention to everything happening around them, science just isn’t quite on board. A study published Wednesday from Linköping University in Sweden finds that your brain can really only concentrate on one thing at a time.

The concept is pretty simple. When you’re concentrating on a visual task like driving, for instance, your brain will adjust its levels of concentration to accommodate the demand. Hearing, in this case, would be diminished.

“The brain is really clever, and helps us to concentrate on what we need to do. At the same time, it screens out distractions that are extraneous to the tas k. But the brain can't cope with too many tasks: only one sense at a time can perform at its peak. This is why it's not a good idea to talk on the phone while driving,” Jerker Rönnberg, a professor of psychology with a focus on disability research at LU, said.

The researchers took 32 students from the university and gave them visual tasks to perform while capturing images of their brains with an fMRI camera while they worked. For example, the students were asked to do things like take an exam. Meanwhile, the researchers changed the level of background noise in the room.

The images showed that activity in the auditory cortex, the region of the brain responsible for hearing, decreased when given visual tasks to complete. The more difficult the task, the less the auditory cortex saw activity. At the same time, when hard visual tasks were handed down, activity in the part of the brain that deals with emotions also decreased.