This may be nothing new to political consultants, but neuroscientists seem to be catching up with the notion that the partisan loyalties of hearts and minds are at least in part dictated by how big, and how active, certain structures of the brain are.
The latest study to support this was published online by the journal Current Biology on April 7, and based on brain imaging of 90 student volunteers (55 of them women) at University College London.
After establishing their political orientation -- very liberal to very conservative on a four-point scale -- through a standard survey of each student, the researchers zeroed in on images of several brain regions thought to guide political leaning.
Lead author Ryota Kanai said the study built on an earlier study by colleagues at UCL who did imaging studies on two members of Parliament and a small number of students, and found differences in the size of two key areas.
In both cases, the researchers found that those holding conservative views tend to have larger amygdale, the almond-shaped organ in the center of the brain that's linked to fear, anxiety and emotion; and a smaller-than-average anterior cingulate, a region of the brain linked to sorting through conflicting information and maintaining a more optimistic outlook. The opposite was true for subjects identified as liberal.
Many psychological reports published over the years have also shown conservatives to be more sensitive to threats in the face of uncertainty, while liberals tend to be more open to new experiences.
Kanai said that while the studies "link such personality traits with specific brain structure,'' they don't take into account other factors or prove that individuals are born with certain brain regions larger or smaller, or that the size adjusts going into adulthood based on life experiences.
"It's very unlikely that actual political orientation is directly encoded into these brain regions, '' Kanai said.
Researchers at Emory University saw things a bit differently as they imaged the brains of avowed hard-core Republicans and Democrats -- 30 each -- during the 2004 presidential campaign. Participants were imaged as they assessed statements in which both candidates had clearly contradicted themselves.
The results, presented at a 2006 conference, showed that the one brain area most associated with reasoning remained stagnant during this process. What they did see light up -- in both groups -- was that anterior cingulate region involved in conflict resolution, but also the orbital frontal cortex, involved in processing emotions, and the posterior cingulate, which is involved in making moral judgments.
Lead author Drew Western figures all those parts of the brain work together to resolve the contradictory comments from the candidate they already favor, while remaining critical of the other guy. And once they had reached conclusions that suited their beliefs, another region of the brain tied to reward and pleasure lit up.
Western, who has written extensively about how our minds sort through facts to reach a desired conclusion, noted that the process is hardly unique to politics, but goes on in many areas of our lives.
Another Emory study, put online April 6 by the Public Library of Science, deals with how we show empathy to those in and out of our social group. Except this time, the model was not conservatives or liberals, but chimpanzees, which were sharing yawns rather than political statements, however related they may be.
Scientists already knew that, along with humans, chimps are the species most likely to pass the inclination to yawn from one to another.
But psychologists at Emory found that, among chimps, yawns are not universal signs of fatigue or boredom, but rather an expression of social connectedness and empathy within a group.
Their study involved 23 adult chimps housed in two separate groups at Emory's Yerkes Primate Research Center. The researchers showed nine-second video clips of other chimps, from both groups, either yawning or doing something else.
Chimps were 50 percent more likely to break into a yawn after watching another member of their clan yawn than when they watched a member of the other group.
The researchers say it's not clear that chimp and human behavior with yawns would be equally exclusive, since chimps naturally live in small social groups, while most humans interact and have varying relationships with far more people.
Other experiments, such as those dealing with seeing someone feeling pain, show humans have more empathy toward members of the same social group than strangers.