One of the things that Pennebaker did was record and transcribe conversations that took place between people on speed dates. He fed these conversations into his program along with information about how the people themselves were perceiving the dates. What he found surprised him.

“We can predict by analyzing their language, who will go on a date — who will match — at rates better than the people themselves,” he says.

Specifically, what Pennebaker found was that when the language style of two people matched, when they used pronouns, prepositions, articles and so forth in similar ways at similar rates, they were much more likely to end up on a date.

“The more similar [they were] across all of these function words, the higher the probability that [they] would go on a date in a speed dating context,” Pennebaker says. “And this is even cooler: We can even look at … a young dating couple… [and] the more similar [they] are … using this language style matching metric, the more likely [they] will still be dating three months from now.”