October 3, 2006

U of C scientists show speakers convey meaning without words

How you speak could be just as important as what you say, according to a group of University scientists. They have published a study showing that humans unconsciously adjust their speech in order to convey information not contained in words themselves.

The study, published in the August 2006 issue of the Journal of Memory and Language, describes the phenomenon, termed “analog acoustic expression,” as a kind of verbal gesturing.

People sometimes gesture with their hands during speech to help communicate information not contained in their words alone. In analog acoustic expression, people unconsciously vary speech properties like loudness, rate, and pitch to do the same thing, explained Hadas Shintel, a research associate in the Center for Cognitive and Social Neuroscience at the U of C.

“This kind of modulation of speech can provide information to [the] listener,” Shintel said.

Shintel co-authored the study with Howard Nusbaum, chairman of the University’s Department of Psychology, and Arika Okrent, a 2002 Ph.D. graduate in psychology at the University.

“Analog” is used to differentiate the phenomenon from arbitrary words, which often have no definite connection to what they represent. For example, the sound of the word “chair” has no inherent connection to a physical chair.

“The relation is purely a matter of convention,” said Shintel. In analog acoustic expression, however, “the sound pattern is related to the meaning it conveys.”

The phenomenon can take place in a number of different ways, according to Shintel.

“People can vary their speech rate when describing objects that move at different speeds, or they can raise and lower their pitch when describing upward or downward motion,” she said.

For example, if a speaker wanted a baseball game to go faster, he might say, “Baseball should be morelikethis,” with the last three words uttered quickly together. But if he wanted it to go slower, he might remark “Baseball should be more…like…this,” saying the last three words slowly, perhaps even with pauses.

This variation in speech rate communicates a speaker’s desire for increased or decreased speed, although the words themselves do not.

Researchers have known for a while that people intentionally adjust their speech to express emotion, but analog acoustic expression is a largely unconscious phenomenon used to express more information than the words themselves contain.

“I think we are not necessarily aware of analog acoustic expression in everyday life; it is these slightly more ‘expressive’ examples that stand out and draw attention,” Shintel said.

To demonstrate the phenomenon, the researchers had subjects describe the up-and-down motion of a dot on a screen, in addition to reading the sentences “It is going up” and “It is going down” with no accompanying visual action.

In both cases, researchers noticed an uptick in pitch as the subjects described upward motion and a corresponding reduction in pitch with downward motion.

They also had the subjects describe the movement of a dot from left to right at varying speeds. The researchers noticed that people spoke more quickly as the dot sped up, demonstrating that analog acoustic expression was used to communicate information not contained in the words “The dot is moving left” or “The dot is moving right.”

Analog acoustic expression provides an exciting field for further research, researchers say. Shintel wants to determine if the phenomenon is related to hand gestures, another non-arbitrary method humans use to convey meaning.

She also suspects people use analog acoustic expression to convey more complex information than the simple movement of a dot used in this study.

“Investigating this phenomenon can help us have a better understanding of the sources of information that are available in spoken language,” which can give a better understanding of language development and comprehension, she said.