Jan. 3, 2008 -- Smiling affects how we speak, to the point that listeners can actually identify the type of smile based on sound alone, according to a new study that also determined some people have "smilier" voices overall than others.
The research adds to the growing body of evidence that smiling and other expressions pack a strong informational punch and may even impact us on a subliminal level.
"When we listen to people speaking, we may be picking up on all sorts of cues, even unconsciously, which may help us interpret the speaker," lead author Amy Drahota told Discovery News.
Drahota, a research fellow in the School of Health Sciences and Social Work at the University of Portsmouth, and colleagues Alan Costall and Vasudevi Reddy recorded volunteers as they went through a rather silly interview that required them to utter the words, "I do in the summer" -- no matter the question.
Examples of questions included, "Do you ever sunbathe?" and, "Do you go skinny dipping?"
"The question schedule was deliberately built up to begin serious and then become gradually more amusing and strange, and potentially slightly embarrassing," Drahota explained.
"All the while the speakers were 'admitting' what they do in the summer -- even if it wasn't true -- and additionally the interview must have seemed most peculiar to the speakers and this would have made them smile."
The researchers videotaped the volunteers and then categorized their smile types. It's believed that some 50 different types of smiles exist, ranging from triumphant ones to those that convey bitterness. For the purposes of this study, however, the scientists focused on four types.
Drahota described the first as an open smile "in which the lips are drawn back, the cheeks are raised and crows-feet wrinkles appear around the eyes." Technically this is called a Duchenne smile, which may be the truest and most intense of all.
The second smile type is like the Duchenne, only minus the "smiley eyes." The third is a suppressed smile, "where the speaker is trying to hide their smile by pulling their lips in or down as they speak." Finally, they denoted times when the speakers weren't smiling at all.
The audio for the interviews was then played back to another group of test subjects. Even without seeing the speakers, the listeners were usually able to identify the type of smile the speaker made as he or she went through the wacky interview.
The findings have been accepted for publication in the journal Speech Communication.
Drahota and her team suspect our smile-sense has to do with changes in pitch.
"When we listen to speech we hear the general pitch, and people associate a rise in pitch with more smiley sounding voices," she said, adding that "we might also be picking up on more subtle cues, like the spread of frequencies within the voice, and how intense the voice is."
A person with a naturally short vocal tract may therefore sound more smiley than others at all times.
How we perceive such smiles may influence our behavior.
Piotr Winkielman, associate professor of psychology at the University of California at San Diego, unconsciously primed some of his study participants with happy faces.
To do this, he showed them photos of faces. Pictures with the happy faces flashed by quickly, before the viewers could consciously detect them, while neutral faces were presented for longer periods. The photo viewers were then offered a drink and asked how much they would pay for it.
Volunteers primed with the subliminal smiles drank more and offered to pay up to triple the price of the offered beverage, which was just a sugary Kool-Aid mixture.
"This is the first demonstration that you can influence consequential, real-world behavior without affecting conscious feeling," Winkielman said. "We can change what you do without changing how you feel."
In future, studies on smiles and other expressions might improve synthetic voices used for disabled individuals. They could also benefit a host of other applications, such as computer games, automated phone systems, text-to-speech technologies and more.
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School of Health Sciences and Social Work at the University of Portsmouth