The participants were given free cellphones to use for the test period but didn't know what researchers were investigating.
In the study, 100 per cent of the participants used emoticons, but they did not use them very often, with only 4 per cent of all their sent text messages containing one or more emoticons.
"We believe that our study represents the first naturalistic and longitudinal study that collects real emoticon use from text messages 'in the wild'," said Philip Kortum, one of the study's authors.
"Texting does not appear to require as much socio-emotional context as other means of nonverbal communications," Kortum said.