Being chauffeured around by buses was always fine with Lauren Emberson, until someone in a nearby seat picked up a cell phone and started yammering away.

“It instantly became a different ride. I couldn’t read at all,” said Emberson, a psychology Ph.D. candidate at Cornell University.

As the offending chatter continued, Emberson found herself inexplicably hanging on every word. “I would chastise myself for listening in,” she said. “But then I started thinking it wasn’t voluntary.”

So, Emberson’s commuting observations became the basis of a study — just published in the journal Psychological Science — of the uniquely annoying qualities of “halfalogues,” a newly coined term for one side of a conversation. By recording cellphone discussions between roommates, and then having each person recap the gab session solo, Emberson and her collaborators were able to gather dialogues, monologues and these halfalogues.

Then they had other subjects try to complete attention-demanding tasks while hearing one of these types of speech. As expected, performance didn’t really dip when dialogues and monologues were in the background.

“People are really good at filtering things out,” Emberson said. But bet you can guess what happened with halfalogues playing. “Even though they wanted to ignore it, they couldn’t,” said Emberson, who admits feeling relief at the finding. “I wasn’t being a bad person eavesdropping all those years.”

Her team hypothesized that it’s not the disrupted flow of speech that’s the problem. It’s the fact that listeners’ brains feel forced to fill in the blanks they’re missing. That’s why they did a follow-up study, having subjects again attempt those tasks with noise in the background. But although the recordings followed the same linguistic patterns as speech, it was too muffled to understand, and thus, wasn’t as distracting.

The tasks the subjects couldn’t focus on weren’t exactly driving in city traffic, but it is a bit disturbing to think that bus drivers could be thrown off by someone speaking into an earpiece.

But the bigger lesson may be for folks who confuse their seats with phone booths. “People have the impression no one is listening to them. But they’re listening whether or not they want to be,” said Emberson, who now feels a bit more justified in telling noisy neighbors to knock it off.

Photo by Attila Kisbenedek/Getty Images