The findings support earlier research on the distracting nature of cell phone chats, but most of those have focused on the user, and not bystanders. Studies have shown, for example, that drivers who talk on cell phones, even in hands-free mode, are as likely to get into an accident as a drunk driver because of their slower reaction time and greater chance of missing stop signs and red lights. Even pedestrians who walk and talk are more likely to be engrossed enough by their conversation to miss signs at crosswalks. “I do think some tasks would be susceptible [to impairment] because some attention is captured by the overheard conversation versus a typical two-sided conversation,” says Galván.

Hearing one side of the conversation, for example, makes it more uncertain and unpredictable, so our brains are naturally drawn to filling out the missing parts, even if we aren’t consciously trying to eavesdrop, she says.

“And that may have implications for open work settings, were people can’t help but overhear colleagues’ conversations, whether they are personal or work-related. “What I think is intriguing is that 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 says. “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.”