Hold the line: Overheard phone calls more distracting than room full of people chatting

People are more distracted by other individuals talking on their mobile phones than by listening in to background conversations between people in the same room, a study has found.

Tests show that an overheard conversation on the phone is significantly more memorable - as well as distracting - for someone involuntarily listening in than if the conversation took place between two people in the same place.

Scientists believe they may have demonstrated why mobile phone conversations often seem more intrusive in a railway carriage or on a bus than the general hubbub of people talking to one another in the background.

“This is the first study to use a realistic situation to show that overhearing a cell-phone conversation is a uniquely intrusive and memorable event,” said Victoria Galvan of the University of San Diego, who led the study published in the on-line journal PLOS ONE.

“We were interested in studying this topic since cell-phone conversations are so pervasive and could impact bystanders to those conversations at work and in other settings of everyday life,” Dr Galvan said.

The study was based on tests carried out on a group of volunteers who were asked to carry out anagram puzzles while, unknown to them, researchers conducted a scripted conversation in the background, either between two people in the room or between someone on a mobile phone and an unknown caller.

“Participants only heard the conversation one time and were unaware that it was part of the study. Participants who overheard the one-sided conversation found the conversation more distracting and annoying,” Dr Galvan said.

“They also remembered more words from the conversation and were more confident in some of their answers on the surprise memory test,” she said.

Rosa Vessal, a co-author of the study, said that a possible explanation for the finding is that people find it easier to follow a two-way conversation and so their brains do not have to work as hard in figuring out what is going on.

“Research suggests that bystanders may pay more attention to a cell-phone conversation because the content of the conversation is unpredictable. Not knowing where the conversation is heading is what makes cell-phone calls more distracting,” Dr Vessal said.

Open-plan offices and communal work places where people routinely make or take phone calls may actually be less productive because of this, according to Dr Galvan, although there is no easy solution if phone calls are needed for the job.

“It's possible that performance could be even greater in an environment with less one-sided conversations. In some situations, this is not feasible; people will need to communicate with co-workers and clients via telephones or impractical to implement because some work places are inherently noisy,” she said.

“But if it was simple to implement and didn't hamper communication, it might be a good idea to have some work areas in which typical conversations were promoted while one-sided phone calls were limited,” she added.

“Bystanders who are exposed to these personal conversations may not have much control over the situation, thereby increasing their levels of annoyance and frustration,” Dr Galvan said.

“Research has shown that bystanders in situations where they are not free to leave - for example, waiting for or using public transportation - often find cell-phone conversations annoying,” she said.