What we say may not reveal as much about ourselves as how we say it, says a UT professor in his upcoming book.

Professor and Psychology Department Chair James Pennebaker and his students have been researching the significance of word use for more than 15 years.

“The basic idea here is that the words we use in everyday language reflect people’s psychological state,” Pennebaker said.

University spokeswoman Michelle Bryant said Pennebaker’s book, “The Secret Life of Pronouns: What Our Words Say About Us,” is a compilation of his research studies, and will be available on Aug. 30.

Pennebaker said there are two general types of words — content words and function words — and that his research focuses on the less-studied function words.

Function words include pronouns, prepositions, articles and other small words, while content words include nouns, verbs, adjectives and adverbs, Pennebaker said.

He said that although there are fewer than 500 function words in the English language, these account for more than half of all words used every day and can help determine what people focus on while speaking.

“It’s not what you’re talking about that predicts your psychological state, it’s how you talk,” Pennebaker said

Pennebaker’s results come from dozens of studies undertaken by him and his students on thousands of people in laboratories, online, historical archives and even across multiple languages.

His laboratory developed a computer text analysis program, called Linguistic Inquiry Word Count, that takes any computerized text and analyzes the percentage of different words as well as other language dimensions.

The researchers found out people who lie tend to use simpler language and avoid the “I” pronoun, providing researchers with what is essentially a linguistic lie detector with 67-percent accuracy, Pennebaker said.

Related to the same pronoun, his team found that people who are depressed tend to use the “I” pronoun more.

“The way people are using pronouns tells us where they are paying attention,” he said.

The higher rate of the “I” pronoun indicates the person is more self-conscious and less involved with the world around them, Pennebaker said.

His team also analyzed speed dating and found that couples with matching language patterns are more likely to continue dating, a prediction that was more accurate than participant’s own self-assessment.

It is only fairly recently that researchers have been able to the understand the connection between psychological states and the words people use, said David Beaver, an associate professor in the department of linguistics.

“This is a very general phenomenon. You can apply it in very simple interactions in a classroom, or you can apply it on a political level to look at the behavior of world leaders,” Beaver said.

He said there is increasingly greater interest in this field of research from military, political, commercial and academic groups, stemming from the wide applicability of easily learning about individuals through their language.

Beaver and Pennebaker are currently working on a research study looking at how people keep secrets and whether they use deceptive language differently from how they use sincere language.