It may be the last place you want to be judged on your looks, but in a court of law it pays to be attractive.

A new Cornell University study has found that unattractive defendants are 22 percent more likely to be convicted, and tend to get hit with longer, harsher sentences—with an average of 22 months longer in prison recommended by the study's participants.

The study identified two kinds of potential jurors: Those who reason emotionally and give harsher verdicts to unattractive defendants, and those who reason rationally and focus less on defendants' looks. One processes information based on facts, analysis, and logic. The other reasons emotionally and may consider such legally irrelevant factors as a defendant's appearance, race, gender, and class, and report that the less-attractive defendant appeared more like the "type of person" who would commit a crime.

"Our hypothesis going in was that jurors inclined to process information in a more emotional/intuitive manner would be more prone to make reasoning errors when rendering verdicts and recommending sentences. The results bore out our hypothesis on all measures," says lead author Justin Gunnell, a Cornell Law School graduate who began working on the study as a Cornell undergraduate student working with co-author Stephen Ceci, professor of developmental psychology.

The authors said the study, "When Emotionality Trumps Reason," will be published in an upcoming issue of the peer-reviewed journal Behavioral Sciences and the Law.

Participants—169 Cornell psychology undergraduates—took an online survey to determine the degree to which they processed information rationally or emotionally. They were then given a case study with a photograph of an actual defendant and his or her general profile. They read real jury instructions and listened to the cases' closing arguments.

While both groups convicted attractive defendants at similar rates and were less biased in the face of strong evidence or very serious offenses, the jurors' reasoning style tended to play out "in cases where the evidence is ambiguous and the charged offense is somewhat minor," says Gunnell, who now practices commercial litigation in New York City.

Gunnell says the study could contribute to refinements in jury selection techniques. In cases where the evidence strongly favors one side, a lawyer might want to identify rational jurors. But in a case with an emotional tug, a defense attorney might try to screen out highly rational jurors.

"Every person is capable of reasoning via either system and likely uses each system to some degree depending on context," Gunnell says. "The degree to which one system predominates the other is a factor that varies, depending on the individual's natural preference and style."

He said the findings are important because "22 months may not seem like a lot to an outsider, but I guarantee that to the person serving the sentence it will seem like a lot."