April 21, 2010  -- Jealousy can be so powerful that it can leave a person "functionally blinded," unable to see key images in their immediate environment. That's the core finding of a study by two psychologists at the University of Delaware, who have been running for cover ever since their study was published in the journal Emotion a few days ago.

Steven Most, a cognitive psychologist, and Jean-Philippe Laurenceau, a specialist in social relationships, conducted two experiments involving a total of 52 romantically involved couples on the Newark campus. They wanted to see if jealousy can be strong enough to cause "emotion-induced blindness."

Their research shows that women who admitted they were jealous when their guy ogled photos of other women (presumably female students at the university who were "accessible") couldn't concentrate on a basic computer task well enough to recognize simple images that flashed quickly across the monitor.

The problem, judging by many reports on the research, is the work showed that women could be blinded by jealousy, but not necessarily men.

Why Women but Not Men?

It was juicy fodder for the Internet, leading one writer to claim the conclusions proved that "scientists hate women." Other comments, which Laurenceau labeled "venomous," cast doubt upon the scientists' credentials, intelligence, and intentions.

"We're definitely not women haters," Laurenceau said in a telephone interview. "I'm married to one, and I have a daughter."

The study targeted women, Most said, because the sample needed to be homogeneous, and men and women apparently have different attitudes about jealousy. Previous studies have also focused on women, so this adds to that data, and the researchers are considering doing other experiments targeting men, although it's not clear if that is going to happen.

In the meantime, the study does show just how vulnerable our perception can be to emotions. The women who participated in the study really were "blinded" by jealousy, Most said, but not in a literal sense.

Jealousy Scrambles Message to the Brain

"The eyes are fine," he said, but the message to the brain was scrambled. The result was "emotion-induced failures of visual perception," as the title of their study put it.

To conduct the experiments, each couple was tested independently of the other couples. The romantic partners sat in a room, separated by a curtain, each facing a different computer monitor.

The woman's task was to watch as images flashed on the screen, visible for only about one-sixteenth of a second.

Most of the views were landscapes, but she was supposed to pick out "target images," buildings tilted 90 degrees to the left, or 90 degrees to the right. The fifth slide before each target image was of an emotional subject, something gruesome or disgusting.

Her partner was told initially to evaluate the attractiveness of some landscapes on his monitor. But about midway through the experiment, the game plan was changed. Instead of landscapes, the male was told to judge the attractiveness of females as they appeared on his monitor. So really the only thing that changed was the guy was looking at girls instead of landscapes.

Jealousy Left Women Participants 'Functionally Blind'

Many of the female participants were really uneasy with that change of direction, they later told the experimenters. And the results showed that the more jealous they became, the more targeted images they missed.

Jealousy, it seems, had left them "functionally blind."

That happens frequently in our daily lives, Most said, although it's not always caused by jealousy.

"There's plenty of examples, especially in auto accidents, where someone is looking right at something, and yet they don't see it," he added. "The eyes are working just fine, but there's something about the visual system in the brain that has a little hiccup."

In the experiments, it was more than a hiccup. Jealousy, Laurenceau said, "is a signal that something is wrong and a relationship might be ending. It's a very strong feeling of insecurity, and you are almost primed to look for other potentially threatening information in the environment. It could be that the disturbing images represented other threats."

Brain Seems Wired to Prioritize Emotional Information

So the female participant sees a photo of a woman being assaulted, or some other grotesque image, and when the building on its side flashes across her screen five images later, she misses it.

"The brain seems to be wired to prioritize emotional information," Most said. "If there's something that's inherently emotional right in front of us, our brain says pay attention to this regardless of whether you want to or not, and the consequence is that we don't see something that comes right afterward."

Laurenceau acknowledged that the subjects in the study were somewhat vulnerable. The women averaged about 19 years of age. All the participants were students at the university.

"For 19-year-olds a big part of their lives is to have relationships," he said. "Last semester I taught a class of freshmen. The point of the class was to help them transition into college. And the biggest things they were focusing on were making friends, dating, and getting good grades, in that order.

"So we picked a population where jealousy would be extremely relevant," Laurenceau said.

Is There a Difference in How Men and Women Handle Jealousy?

So would the same findings apply to more mature relationships? That would likely depend on the security of the relationship, he said.

And is there a difference in how men and women deal with jealousy, and how it affects their visual perception?

Both researchers said that question is beyond the focus of their studies.

Others, however, have suggested that there are considerable differences between the genders. Evolutionary psychologists have argued that men tend to get more jealous than women if it has to do with sexual infidelity, and women get more jealous than men if there's a threat of emotional infidelity.

Regardless of age, and regardless of the type of emotion, and regardless of gender, jealousy and other feelings become particularly powerful in the context of our relationship with others.

It is in social relationships, Most said, that "we experience our strongest emotions." And sometimes, according to this research, those emotions can be strong enough to render us temporarily blinded. Whether male or female.