Younger tweeters, the University of Twente doctoral student found, were more likely to talk about themselves, use text speak, use ALL CAPITALIZED words and employ alphabetical lengthening, like writing “niiiiiiice” instead of “nice.” Among the top features associated with young people were the word school—which makes sense given that they’re more likely to be in it—the pronoun I, the articulated laughter haha and the classic happy face “:)”.

Older tweeters, meanwhile, were more likely to tweet out well-wishing phrases like good morning and take care. And their style is the kind we’d associate with better education: They used more complex language, longer tweets, longer words and more prepositions like for, to and under. The elder crowd also has a higher usage of links and hashtags. Nguyen theorizes that this is related to a stronger desire to share information and “impression management.”

Though an automated system analyzing word use did a better job picking out the age of tweeters, Nugyen found that it was much harder for both automatons and humans to predict the age of older users. The variables they studied show little change after about 30 years of age, Nguyen tells TIME: “For example, the difference between the language of a 13-year-old and a 18-year-old is much larger (on average) than the difference between the language of a 40- or 50-year-old.”