MONDAY, Sept. 27 (HealthDay News) -- Overhearing someone talk on a cell phone can be very annoying because it makes it hard, if not impossible, to concentrate on what you're doing, according to a new study.

Hearing just one side of the conversation is much more distracting than hearing both sides and erodes your attention to other tasks, explained Lauren Emberson, a psychology Ph.D. candidate at Cornell University.

She played recordings of one side and both sides of a conversation to volunteers as they tried to complete computer tasks that required attention, such as using a mouse to track a moving dot. The participants did much worse on the task when they could hear only half of the conversation, she discovered.

Your brain tends to ignore predictable things, but pays more attention to unpredictable situations. When you hear both sides of a conversation, it flow predictably. But just one side of phone conversation is quite unpredictable, Emberson explained -- that's why it's so hard to shut out.

The study appears in the journal Psychological Science.

Talking on a cell phone in public "has a really profound effect on the cognition of people around you, and it's not because they're eavesdropping or they're bad people. Their cognitive mechanism basically means that they're forced to listen," Emberson said in an Association for Psychological Science news release.

More information

For more on evolving cell phone etiquette, please visit PBS's Media Shift.