One-Sided Conversations

One-Sided Conversations Photo Credit: Clipart.com

Overhearing one end of a cell phone conversation may distract you in ways that a two-way conversation wouldn't.


Cell phone half-alogues. I'm Bob Hirshon and this is Science Update.

Hearing someone else talk on a cell phone can be incredibly distracting. A new report in the journal Psychological Science may explain why.
Cornell University psychologist Lauren Emberson and her colleagues played different versions of a recorded cell phone call to people taking a computerized attention test.


And we find that when people listened to only half the conversation, they perform markedly worse than when they hear both halves of a conversation.

In fact, hearing the full conversation didn't impact their performance at all. And the half-conversations were distracting only when they could be clearly understood. As to why, Emberson notes that unpredictable patterns are known to be more distracting than predictable ones. And she suspects that our brains are easily lured into making sense of the one-ended phone calls. I'm Bob Hirshon, for AAAS, the science society.

Making Sense of the Research

It may seem hard to believe, but there was a time not long ago when we would almost never hear someone carrying on a phone conversation in a public place. Today, we hear them everywhere, all the time. But no matter how used we are to the experience, it can seem hard to tune out a one-sided, cell phone conversation, at least compared to one where every speaker is physically in the room. 

Emberson and her colleagues decided to test this common observation scientifically. Sure, some people say they find one-sided phone calls distracting, but is that really the case? To find out, they set up an experiment. They started by recording cell-phone conversations between pairs of undergraduate students (with their permission, of course). They recorded each speaker on a different audio track, so they could manipulate the recording to play back just one side of the conversation, or both.

Next, they brought in a group of other volunteers to perform two different computerized tasks that tested different types of attention. In one task, the user had to track a dot with the computer mouse as it moved around the screen. Emberson compares this kind of attention to driving a car on an empty highway: it's continuous, but not terribly demanding, and the level of attention required doesn't change. The other task was more like driving in traffic: the user had to memorize four letters of the alphabet, and push a button when she saw any of those letters on the screen. Her score went down if she either failed to respond to the target letter, or mistakenly responded to an incorrect letter. This is the kind of attention that involves reacting to new information, and making frequent snap judgments. 

The volunteers performed these tasks when listening to either the full conversation, a half-conversation, or silence. Listening to a whole cell phone conversation didn't affect the volunteers' attention: they performed as well in this condition as they did with no background noise at all. However, they scored lower when listening to a one-sided conversation. 

That indicates that the half-conversations were more distracting, but why? Past studies suggested that we're more distracted by unpredictable stimuli than predictable ones. The one-sided conversations were unpredictable in at least two ways: First, one never knew when the speaker would stop talking, and then start up again, so the sound itself was unpredictable. Second, because the listener was missing half the conversation, the actual content of the other half was unpredictable as well. 

To separate these two effects, the researchers performed another experiment, where they ran the one-sided conversations through an audio filter that made them impossible to understand. These conversations would still have the unpredictable sound, but not the unpredictable content —since no content at all was communicated. In this condition, the distraction effect went away; subjects performed as well on the attention task as they did in the full-conversation or silence conditions.

Taken together, the results suggest that when we hear a one-sided conversation, our brains automatically try to make sense of the missing information, even if we don't really care about what they're saying. Since our attention is limited, the tendency to decipher the phone call fights with whatever we're trying to pay attention to at the time. It also suggests that if you're the one making the phone call, your neighbors probably can't help but eavesdrop a little bit—so be careful what you say.

Now try and answer these questions:

  1. Why did the researchers conduct this study?
  2. Explain how the methods the researchers used helped to answer the question scientifically.
  3. What was the purpose of the follow-up experiment, in which the speakers were made impossible to understand?
  4. Based on these results, do you think a one-sided conversation in a foreign language would be distracting? Why or why not?

You may want to check out the October 22, 2010, Science Update Podcast to hear further information about this Science Update and the other programs for that week. This podcast's topics include: why listening to half of a cell-phone conversation is so distracting, how we choose which hand to use, why we'll pay more if we can touch a product, and the mechanisms behind a fast-acting antidepressant.

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