The audio for the interviews was then played back to another group of test subjects. Even without seeing the speakers, the listeners were able to hear the different types of smile the speaker made as he or she went through the wacky interview.
"A voice contains a variety of acoustical characteristics" said Drahota. "It's possible that we interpret these 'flavours' in someone's voice almost without noticing."
(Image: Another smile ..., a Creative Commons Attribution-ShareAlike photo from Ferdinand Reus's Flickr stream)