Most everyone has had the pleasure of being stuck in close quarters with a person who feels compelled to speak as loudly as possible into their cell phone. Annoying cell phone conversations are such a popular pet-peeve that it’s not uncommon to have “quiet cars” on trains, or signs banning cell phones in certain public locations. It’s quite likely that you have been on a train or bus where two people were talking to each other, and yet you didn’t have the same reaction you had to a person chatting into his phone. Excepting libraries, people chatting with each other rarely provokes public ire. So what is it about cell phone conversations that make them so distracting?

A recent study by Lauren Emberson, published in Psychological Science gives the clue. While volume may be a cause for irritation, it seems that the one-sided nature of cell-phone conversations is what makes them particularly distracting. While asking test subjects to perform tasks while they could overhear conversations (either as dialogues or monologues), it was one sided conversations that had the distracting effect. You can probably recall a situation when you were overhearing a conversation. Not knowing what the person on the other end of the conversation is saying prompts us to fill in the missing pieces of the dialogue. When we can see and hear both sides of the conversation, it is easier to ignore what’s going on. Hearing one side of the story presents a mystery the brain almost can’t help get engrossed in, even if it is someone rattling off a grocery list, or what new shampoo is keeping their poodle looking her best.

Maybe you could be less annoying by repeating everything your chatting partner says so that all the mystery is removed from the situation, and people can better ignore you.