Why Overheard Phone Calls Are Distracting

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Overhearing a one-sided cellphone call is more distracting than eavesdropping on both sides of a conversation, a new study finds.

There are now as many cellphone subscriptions as there are people on Earth, according to the International Telecommunication Union, the United Nations telecommunications agency. As mobile phones increasingly permeate society, with people spending an estimated 2.30 trillion minutes using wireless devices over the last year, scientists want to study the impact cellphones might have on daily life.

"People find cellphone conversations annoying — survey results indicate that up to 82 percent of people do," Veronica Galván, a cognitive psychologist at the University of San Diego, told TechNewsDaily. "We were curious to see what cognitive effects overhearing cellphone conversations might have, since they are now so pervasive in everyday life."

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To see how precisely cellphone chatter might distract people, Galván and her team had about 150 volunteers complete a task where they had to unscramble letters to form words — for instance, rearrange "suohe" to form "house." As the volunteers performed the task, the scientists carried out a short, scripted conversation in the background that volunteers were unaware was part of the study. Half the volunteers overheard one side of a chat carried out on a cellphone, while the rest overheard the conversation as a discussion between two people in the room with them. The discussions involved a mundane topic, such as shopping for furniture, a birthday party and meeting a date at the mall.

The people who overheard the one-sided mobile phone call thought the background conversation was far more distracting than those who heard it as a chat between two people.

"This is the first study to use a realistic situation to show that overhearing a cellphone conversation is a uniquely intrusive and memorable event," Galván said.

People not only thought cellphone conversations were more attention-grabbing, but they also remembered more words and content from the cellphone discussions than they did from two-sided conversations and made fewer errors recognizing which words were part of the phone call. Past research suggests this is due to how one-sided conversations are more unpredictable than ones where people can hear both sides of a discussion.

"Not knowing where the conversation is heading is what makes cellphone calls more distracting," said study co-author Rosa Vessal at the University of San Diego.

Galván recalled how distracting cellphone calls could be in her own life.

"We'd been doing the study for a couple of months, and I was at the store looking at clothes, and the lady next to me was on a cellphone saying, 'Yeah, he was in jail last night,'" Galván said. "I had no idea what she was talking about — it was just a snipped-off conversation without context, and it really was different from a conversation you could hear both sides of."

In the future, the researchers plan on seeing whether people are more susceptible to distraction while eavesdropping on cellphone calls and performing certain kinds of tasks rather than others.

"It's going to difficult to ever get rid of cellphones, since they're now such an important means of communication," Galván said. "Still, it's my guess that some tasks are more susceptible to distraction by cellphone conversations than others, and so it's possible calls might get more restricted in areas where they might distract people from important tasks."

Galván, Vessal and their colleague Matthew Golley detailed their findings online March 13 in the journal PLOS ONE.