The next time you go on a date, don't worry about whether your hair is perfectly combed or your palms are a little sweaty, or if you can possibly eat a taco at the restaurant without getting meat stuck in your teeth and guacamole all over your lap. What you say is what matters to the person across the table, at least when it comes to your "thes".

Last week, Scientific American published an article on social psychologist and author of the upcoming book, The Secret Life of Pronouns, James Pennebaker. Pennebaker recorded the four-minute-long conversations of 80 speed daters, attempting to predict if each couple would—or wouldn't—want to go on a second date. On the tapes, he wasn't looking for awkward pauses or even lonely sighs, but instead for each person's use of seemingly innocuous words like "an," "as" and "her."


These words—also known as function words—send out signals during conversations. For example, using a lot of "thes" can make a person seem more formal or distant, while using a lot of personal pronouns can indicate a more revealing or intimate speaker—say, somebody who might tell stories about "her" or "him" or "them." When examined, function words create emotional-linguistic portraits that may reveal if two people share the same mind-set. "We aren't even aware of it as we talk," says Dr. Pennebaker. "We need a computer to record and analyze each sentence."
 
Enlisting that computer, his team predicted which couples were going to go out again—often with better accuracy than the individuals had on their own. "A lot of the time, the guy would say, 'That speed date was amazing!'" says Pennebaker. "And she would say, 'Oh God, that was awful.' Which is perfectly in line with our findings about function words. The two people walked away with different impressions. They're not on the same page."

In another related study, Pennebaker analyzed the writing of famous poet couple Elizabeth Barrett Browning and Robert Browning as well as that of famous poet couple Ted Hughes and Sylvia Plath. The former (married harmoniously for 15 years until Elizabeth's death in 1881) used many of the same function words, while the later (divorced cataclysmically after six years) failed to share the same love of "it"...and "we" and "us."