From cable TV news pundits to red-meat speeches in Iowa and New Hampshire, our nation’s deep political stereotypes are on full display: conservatives paint self-indulgent liberals as insufferably absent on urgent national issues, while liberals say fear-mongering conservatives are fixated on exaggerated dangers to the country.

A new study from the University of Nebraska-Lincoln (UNL) suggests there are biological truths to such broad brushstrokes.

In a series of experiments, researchers closely monitored physiological reactions and eye movements of study participants when shown combinations of both pleasant and unpleasant images. Conservatives reacted more strongly to, fixated more quickly on, and looked longer at the unpleasant images; liberals had stronger reactions to and looked longer at the pleasant images compared with conservatives.

To gauge participants’ physiological responses, they were shown a series of images on a screen. Electrodes measured subtle skin conductance changes, which indicated an emotional response. The cognitive data, meanwhile, was gathered by outfitting participants with eyetracking equipment that captured even the most subtle of eye movements while combinations of unpleasant and pleasant photos appeared on the screen.

While liberals’ gazes tended to fall upon the pleasant images, such as a beach ball or a bunny rabbit, conservatives clearly focused on the negative images — of an open wound, a crashed car or a dirty toilet, for example.

Consistent with the idea that conservatives seem to respond more to negative stimuli while liberals respond more to positive stimuli, conservatives also exhibited a stronger physiological response to images of Democratic politicians — presumed to be a negative to them — than they did on pictures of well-known Republicans. Liberals, on the other hand, had a stronger physiological response to the Democrats — presumed to be a positive stimulus to them — than they did to images of the Republicans.

By studying both physiological and cognitive aspects, the researchers established unique new insights into the growing notion that political leanings are at least partial products of our biology, UNL political scientist and study co-author Kevin Smith said.

UNL political scientist and co-author John Hibbing said the results might mean that those on the right are more attuned and attentive to aversive elements in life and are more naturally inclined to confront them. From an evolutionary standpoint, that makes sense, he said.

The results also are consistent with conservatives’ support of policies to protect society from perceived external threats (support for increased defense spending or opposition to immigration) and internal ones as well (support for traditional values and being tough on crime), Hibbing said.

Rather than believing those with opposite political views are uninformed or willfully obtuse, the authors said, political tolerance could be enhanced if it was widely understood that political differences are based in part on our physiological and cognitive differences.

“When conservatives say that liberals are out of it and just don’t get it, from this standpoint, that’s true,” Hibbing said. “And when liberals say ‘What are (conservatives) so frightened of? Is the world really that dangerous?’ Given what each side sees, what they pay attention to, what they physiologically experience — the answer is both sides are right.”

The study, funded in part by the National Science Foundation, is to be published in Philosophical Transactions of the Royal Society B on Jan. 23.

Note: this story was written based on a statement issued by the University of Nebraska-Lincoln. We have since been informed by UNL that it has placed an embargo on the article until January 23 and has removed its statement from the Web, so we are unable to provide further details at this time. — Ed.