Best friends or married couples may think they communicate pretty well with each other, but psychologists have found they may not -- at least, not as well as they think.

And in some cases, the spouses communicate no better than strangers.

“People commonly believe that they communicate better with close friends than with strangers. That closeness can lead people to overestimate how well they communicate,” said Boaz Keysar, a professor in psychology at the University of Chicago and a leading expert on communications.

The reason, the researchers said, was due to a phenomenon they call the "closeness-communication bias."

To test their theory, Keysar’s colleague Kenneth Savitsky, professor of psychology at Williams College in Williamstown, Mass., devised an experiment resembling an old-fashioned parlor game to study communication styles between married couples.

During the experiment, two sets of couples sat in chairs with their backs to each other and tried to discern the meaning of ambiguous phrases the other said. In all, 24 married couples participated.

The researchers had each participant say some phrases commonly used in everyday conversations. The participant’s spouse would answer what they thought was the meaning to the phrase, then one of the strangers would answer.

The spouses consistently overestimated their ability to communicate, and did so more with their partners than with strangers.

“A wife who says to her husband, 'it’s getting hot in here,' as a hint for her husband to turn up the air conditioning a notch, may be surprised when he interprets her statement as a coy, amorous advance instead,” said Savitsky, the study’s lead author.

According to Savitsky, the speakers expected their spouse to understand them better than the strangers, but accuracy rates for spouses and strangers were statistically identical.

“This result is striking because speakers were more confident that they were understood by their spouse. Some couples may indeed be on the same wavelength, but maybe not as much as they think,” said Savitsky.

Similar experiment

Savitsky conducted a similar experiment with sixty Williams College students to test if close friends had the same trouble communicating as some married people do.

Like in the study of married couple, the students overestimated their effectiveness in communicating with friends.

So what gives? Why do we have trouble communicating with the people closest to us?

Keysar chalks it up to familiarity; when a speaker assumes that a well-known acquaintance has all the information the speaker has, he or she doesn’t feel the need to provide a long explanation.

But when people meet a stranger, they automatically provide more information because they don’t have a “closeness bias” in that encounter.

In the same way, listeners may wrongly assume that a comment or request from a close acquaintance is based on knowledge that the two have in common -- a mistake the listener would not make with a stranger.

In order to test that idea, a team at Keysar’s lab set up an experiment where two students sat across from each other, separated by a box with square compartments containing various objects. Some of the objects were not visible to one of the students.

The student who was speaking asked their partner to move one of the objects. Unbeknownst to the speaker, his or her request could sometimes be interpreted in two different ways. For example, if the speaker asked his or her partner to move a "mouse," it could either mean a computer mouse or a stuffed animal that only the partner could see.

The study revealed that when partners were asked to move an object with an ambiguous name, they would hesitate longer when the speaker was a friend.

Faster to focus

But when the speaker was a stranger, the partner would be faster to focus on the object that the speaker could see, and ignore the object that the speaker did not know about.

This showed that the participants were more likely to take an egocentric position when working with a friend, neglecting to consider the possibility that the friend didn’t share the same information they had.

“Our problem in communicating with friends and spouses is that we have an illusion of insight. Getting close to someone appears to create the illusion of understanding more than actual understanding,” said co-author Nicholas Epley, a professor of behavioral science at the University of Chicago Booth School of Business.

"The understanding, 'What I know is different from what you know' is essential for effective communication to occur," Savitsky said. "It is necessary for giving directions, for teaching a class or just for having an ordinary conversation. But that insight can be elusive when the ‘you’ in question is a close friend or spouse."

The paper, "The Closeness-Communications Bias: Increased Egocentrism among Friends versus Strangers," was published in the January issue of the Journal of Experimental Social Psychology.