Sali Tagliamonte and Derek Denis claim in a New Scientist article that IM allows teenagers to deploy a "robust mix" of colloquial and formal language.
In a paper to be published in the spring 2008 issue of American Speech, the researchers argue that, far from ruining teenagers' ability to communicate, IM lets them show off what they can do with language.
"IM is interactive discourse among friends that is conducive to informal language," Denis told New Scientist. "But at the same time, it is a written interface which tends to be more formal than speech."
Denis and Tagliamonte analysed more than one million words of IM communications and 250,000 spoken words produced by 72 people aged between 15 and 20.
They found that, although IM shares some of the patterns used in speech, its vocabulary and grammar tend to be relatively conservative.
Abbreviations made up just 2.4 percent of the vocabulary of IM conversations, which the researchers describe as an "infinitesimally small" proportion.
And rumours of the demise of 'you' would appear to have been greatly exaggerated, as it was preferred to 'u' a whopping nine times out of 10.