People talk on their cell phones everywhere - in stores, in parks, in the hallway outside my office. Although I hate overhearing someone's phone conversation, I'm frequently forced to listen to half a conversation because people near me are talking on their cell phones. I find it annoying and distracting. I'm willing to guess that you've also been annoyed and distracted by overheard cell phone conversations.

I've written a few blog posts regarding the dangers of trying to navigate while talking on a cell phone (Hang Up and Drive; Unicycling Clowns, Train Wrecks, and Pilots Forgetting to Land) or while texting (Texting Zombies). In essence, using a cell phone makes you less aware of the world around you and thus more dangerous while driving or walking. In this post, I am writing about the problems posed for the people surrounding that person blabbing away on that cell phone.

I've recently come across research concerning the effects of overhearing cell phone conversations. Interestingly, overhearing someone's cell phone conversation is worse than overhearing two people talking face-to-face.

First, and not surprisingly, people find overhearing cell phone conversations annoying. In a very funny experiment, Monk, Carroll, Parker, and Blythe tested people's reactions to overhearing cell phone and face-to-face conversations. Their researchers (2 female students) conducted short conversations in public. They had their conversations either face-to-face or over a cell phone. They also varied volume - either normal conversation level or loud. After they finished their conversation, one of the women turned to the person near them and asked them questions about the experience of overhearing someone's conversation. ("Hi, we're conducting research on how overhearing other people's conversations affect people in public places." I like the image of the researcher turning to the bystander, starting that interview, and then asking how intrusive it was and if the people were listening in.) Loud conversations were rated as more intrusive and annoying than normal volume conversations, thus documenting the obvious. But cell phone conversations were always rated as more intrusive and annoying than face-to-face conversations.

Maybe you've noticed this in your own experiences. Sometimes overhearing two people talking can be annoying. But overhearing just one side of a cell phone conversation always seems to be annoying. How annoying? Some people have developed cards to hand rude cell phone users (I've included an image of one such card already filled out).

Those overheard cell phone conversation are not only annoying, they are also distracting. In a paper just published in Psychological Science on-line, Emberson and colleagues studied whether overhearing a cell phone conversation is more distracting than listening to other forms of speech. They gave people some straightforward vigilance tasks to perform - follow a moving dot on a computer screen or respond whenever certain letters and numbers appeared in a long series of letters and numbers. At the same time, the people listened to background speech. Emerson and colleagues played both sides of a cell phone conversation (a dialogue), only one side of a cell phone conversation (a halfalogue - I love this term), one person talking (a monologue), or silence. Overhearing a halfalogue, that is one side of a cell phone conversation, was the most disruptive. Through an additional study, Emberson and colleagues concluded the distraction is caused by the lack of predictability and understandability of hearing only half of a conversation. Even though you are told to ignore the speech and you really try to ignore it, your attention system constantly tries to make sense of the verbal information around you. You can't stop listening. Making sense is easier and less distracting when you hear both sides rather than one side of a conversation.

My conclusion? Using a cell phone in public is just bad. Since you are less aware of the world around you when using your cell phone, you are a hazard on the road and on the sidewalk. In addition, since the people around you have to listen to your halfalogue, you are annoying and distracting. I love my cell phone, but I am pledging to not annoy and distract everyone around me.