Online dating is rough enough when people are all above-board and honest about themselves, their past, their plans and preferences. But, when you throw dishonesty into the mix, it can get ugly fast. No one wants to wind up investing time in ursine a relationship that started off on lies, online or off.

Two professors are now shedding some light on how liars behave on online dating sites.

“Generally, people don’t want to admit they’ve lied,” says Catalina Toma, communication science professor at the University of Wisconsin–Madison. “But we don’t have to rely on the liars to tell us about their lies. We can read their handiwork.”

Using personal descriptions written for Internet dating profiles, Toma and Jeffrey Hancock, communication professor at Cornell University, have identified clues as to whether the author was being deceptive.

The researchers compared the actual height, weight and age of 78 online daters to their profile information and photos on four matchmaking websites. A linguistic analysis of the group’s written self-descriptions published in the February issue of the Journal of Communication revealed patterns in the liars’ writing.

The more deceptive a dater’s profile, the less likely they were to use the first-person pronoun “I.”

“Liars do this because they want to distance themselves from their deceptive statements,” Toma says.

The liars often employed negation, a flip of the language that would restate “happy” as “not sad” or “exciting” as “not boring.” And the fabricators tended to write shorter self-descriptions in their profiles — a hedge, Toma expects, against weaving a more tangled web of deception.

“They don’t want to say too much,” Toma says. “Liars experience a lot of cognitive load. They have a lot to think about. They less they write, the fewer untrue things they may have to remember and support later.”

Liars were also careful to skirt their own deception. Daters who had lied about their age, height or weight or had included a photo the researchers found to be less than representative of reality, were likely to avoid discussing their appearance in their written descriptions, choosing instead to talk about work or life achievements.

The toolkit of language clues gave the researchers a distinct advantage when they re-examined their pool of 78 online daters.

“The more deceptive the self-description, the fewer times you see ‘I,’ the more negation, the fewer words total — using those indicators, we were able to correctly identify the liars about 65 percent of the time,” Toma says.

A success rate of nearly two-thirds is a commanding lead over the untrained eye. In a second leg of their study, Toma and Hancock asked volunteers to judge the daters’ trustworthiness based solely on the written self-descriptions posted on their online profiles.

“We asked them to tell us how trustworthy the person who wrote each profile was. And, as we expected, people are just bad at this,” Toma says. “They might as well have flipped a coin … They’re looking at the wrong things.”

About 80 percent of the 78 profiles in the study, which was supported by the National Science Foundation, strayed from the truth on some level.

“Almost everybody lied about something, but the magnitude was often small,” Toma says.

Weight was the most frequent transgression, with women off by an average of 8.5 pounds and men missing by 1.5 pounds on average. Half lied about their height, and nearly 20 percent changed their age.

Studying lying through online communication such as dating profiles opens a door on a medium in which the liar has more room to maneuver.

“Online dating is different. It’s not a traditional interaction,” Toma says.

For one, it’s asynchronous. The back-and-forth of an in-person conversation is missing, giving a liar the opportunity to respond at their leisure or not at all. And it’s editable, so the first telling of the story can come out exactly like the profile-writer would like.

“You have all the time in the world to say whatever you want,” Toma says. “You’re not expected to be spontaneous. You can write and rewrite as many times as you want before you post, and then in many cases return and edit yourself.”

Toma says the findings are not out of line with what we know about liars in face-to-face situations.

“Online daters’ motivations to lie are pretty much the same as traditional daters’,” she says. “It’s not like a deceptive online profile is a new beast, and that helps us apply what we can learn to all manners of communication”

But don’t go looking just yet for the dating site that employs Toma’s linguistic analysis as a built-in lie detector.

“Someday there may be software to tell you how likely it is that the cute person whose profile you’re looking at is lying to you, or even that someone is being deceptive in an e-mail,” Toma says. “But that may take a while.”