Sept. 22, 2010 -- Overhearing a cell phone conversation is not only annoying but distracting because it leads the brain into trying to decipher what the person on the other end of the call is saying, making concentration more difficult, a new study shows.
Cornell University doctoral student Lauren Emberson, BSc, and colleagues enlisted 41 volunteers to test whether their thinking abilities were most affected by listening to two people talking in conversation, a monologue, silence, or only one side of a conversation, called a “halfalogue.”
The results were clear -- the participants listening to only one side of a conversation had lower scores on a series of cognitive tests that required attention and focus.
Emberson tells WebMD in an email that listening to only one side of a conversation drains concentration, because the brain must work harder to figure out what the other person might be saying.
Prediction a Key to Understanding
People who hear only one side of a conversation get less information and thus can’t predict what’s being said, Emberson tells WebMD.
When listening to a monologue or to a two-sided conversation, it’s easier to predict what speakers will say next. But the human brain can’t make predictions, she says, when it hears only one side, which also may explain why people become annoyed when they overhear others on cell phones.
Emberson tells WebMD the study shows that “hearing both halves is not distracting, but hearing one half of a conversation is. Our paper also includes a control [comparison] study showing that when the information content of the speech is unintelligible, the half of a conversation doesn’t affect your attention.”
The same is likely true when people are trying to read or watch TV at the same time someone is talking nearby on a cell phone or even a landline, she says.
Predicting Is a Reflex
“Attention is reflexively shifted to their conversation because of the unpredictability of the speech,” Emberson tells WebMD.
She enlisted two pairs of college roommates as they talked on a cell phone, then recorded each conversation both as a dialogue, in which both women could be heard by a listener, and as a halfalogue, in which only one side of the conversation could be discerned. Then each woman recapped the conversation in a monologue. The recordings were played back as volunteers performed various tasks on a computer, such as tracking a moving dot using a mouse.
She says people just can’t help it -- that human brains pay more attention to things that aren’t predictable.
Emberson tells WebMD that she came up with the idea for the study while commuting by bus and noticed that she couldn’t read or even concentrate on music when someone nearby was talking on a cell phone.
“I used to think that I was eavesdropping, but these results suggest it is beyond my control, that my attention is reflexively shifted to their conversation because of the unpredictability of the speech,” Emberson tells WebMD.
She says in a news release that overhearing half of a conversation “has a really profound effect on the cognition of the people around you, and it’s not because they’re eavesdropping or they’re bad people. Their cognitive mechanism basically means that they’re forced to listen.”
How to Deal With Halfalogues
So here’s what Emberson tells WebMD people might consider when being subjected to a halfalogue.
- Ask the person on the mobile device to put the conversation on speaker phone, which would make what they say less distracting.
- Put in earplugs, which would make “the effect of the unpredictability of the speech go away.”
The research has possible ramifications that go beyond what is already known - that talking on cell phones distracts drivers. It’s likely that a passenger in a car using a cell phone could also distract a driver’s attention, though this notion needs more research.
The study is published in the Sept. 21 issue of Psychological Science.