Women are twice as likely as men to use emoticons in text messages, according to a new study from Rice University.

The symbols, which began as happy and sad smiling faces but have since morphed into dozens of expressions, have become hugely popular in text messages and email.

The new study used smartphone data from men and women over six months and analysed 124,000 text messages.

The participants were given free iPhones to use for the test period but didn't know what researchers were investigating.

The team says the study was unique.

'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, assistant professor of psychology at Rice and one of the study's authors.

Texting has become one of the most popular forms of communication in society worldwide.

This year alone, it is estimated that 8 trillion text messages will be tapped out across the world.

In the Rice study, 100 percent of the participants used emoticons, but they did not use them very often, with only 4 percent of all their sent text messages containing one or more emoticons.

'Texting does not appear to require as much socio-emotional context as other means of nonverbal communications,' Kortum said.

'It could be due to texting's simplicity and briefer communication, which removes some of the pressures that are inherent in other types of non-face-to-face communication, like email or blogs.'

The study also confirms previous research that women are more emotionally expressive in nonverbal communication; however, in this research, the authors found that while women may use emoticons more than men, the men used a larger variety of emoticons to express themselves.

Participants in the Rice study texted a wide variety of emoticons.

Seventy-four different emoticons were used, but the top three emoticons happy, sad and very happy made up 70 percent of the total emoticons sent by the study participants.

Kortum and his co-authors pointed out that their study is a glimpse into the complex nature of real mediated communications.

They said that additional inquiry in real-world settings are needed to understand the complexities of human communications through technology.