Fuel for Thought

Day after day an overbear-ing colleague grates on your nerves. It’s a battle to keep your irritation under wraps. Suddenly, during a particu-larly long encounter, you snap—you lose your temper and give your shocked co-worker a piece of your mind.

Most of us blame our-selves for such lapses in willpower, but new research suggests that willpower may not be available in an unlimited supply. Scientists have discovered that a single, brief act of self-control expends some of the body’s fuel, which undermines the brain’s ability to exert further self-discipline.

Researchers at Florida State University asked volunteers to perform tasks such as ignoring a distracting stimulus while watching a video clip or suppressing racial stereotypes during a fi ve-minute social interaction. These seemingly trivial efforts depleted glucose in the bloodstream and hindered volunteers’ ability to maintain mental discipline during subsequent tasks. When the study participants were given a sugar drink to boost their blood glucose levels, their performance returned to

normal. Volunteers who drank an artifi cially sweetened drink remained impaired.

“These fi ndings show us that willpower is more than a metaphor,” notes Matthew Gailliot, a graduate student in psychology who led the research. “It’s metabolically expensive to maintain self-control.”

“These are remarkably provocative results,” says Kathleen Vohs, a psychologist at the University of Minnesota. Her research suggests that those who exercise self-control are more likely to make impulse purchases—a fi nding that fi ts with the glucose depletion model. Vohs observes that one tantalizing implication of the results is that self-control may be toughest for people whose bodies do not utilize blood glucose properly, such as those with type 2 diabetes. Unfortunately, such people cannot benefi t from the news that a sugar drink restores mental reserves. Nor should anyone take the fi ndings as license to go on frequent sugar benders in the name of willpower. Although glucose’s precise role in self-regulation is not yet clear, Vohs says, “We can be assured that it’s going to be more nuanced than that.” —Siri Carpenter

The Face of a Winner

Most of us think we elect our leaders based on their politics. But new research reveals that it might be the candidates’ faces that count.

Anthony Little of the University of Stirling in Scotland and his colleagues modifi ed the faces of candidates from eight different political races in the U.K., the U.S. and New Zealand. Using a com-puter, he combined the real faces with a picture of an “average” face made from a com posite of sev-eral different people. The resulting images pre-served the politicians’ important facial features but rendered the contestants unrecognizable.

Then, volunteers in the lab examined each new pair of runners and decided who would be a better leader based on the faces alone. In all eight races, they chose the face of the politician who had won the actual election—George W. Bush redefeated John Kerry, and Tony Blair upset John Major once again.

Research has shown that people make a lot of judgments about others based on their faces and that most will agree about whether a face looks aggressive, intelligent or kind, for example. The tendency to judge individuals by their faces might have been useful early in human history, when our ancestors lived in small groups and chose leaders based entirely on personal characteristics, Little says. For instance, in dangerous times people tend to prefer dominant faces, as signaled by features such as a prominent chin and heavy brow.

Little says that it is unlikely that only the face counts in a political election. But the research does suggest that part of our gut feelings about candidates comes from unconscious assessments we make based solely on their faces. —Kurt Kleiner

■ Adoptive parents spend more time and money on their kids than biological parents do, found a study of two-parent fami-lies carried out at Indi-ana University Blooming-ton and the University of Connecticut. In addition to spending more quality time reading or convers-ing with their children, adoptive parents devot-ed a greater percentage of their total income to their kids. These results, the sociologists suggest, may mean that kids are not necessarily better off with their birth parents—contrary to widespread belief.

■ Researchers have found the fi rst physiological evi-dence that subliminal im-ages do register subcon-sciously. Brain scans showed that even though volunteers were not aware of a series of quick-ly fl ashed images, their vi-sual-processing centers activated in response to the pictures. The study, from University College London, did not address whether subliminal imag-es could infl uence thought or behavior.

■ Hormones get the blame for many teen behaviors. Now add to the list over-reactions to emotional situations. In response to stress, all bodies pro-duce the hormone THP, which reduces anxiety and calms brain activity in adults and children. In adolescents, however, THP has the opposite ef-fect—it excites the brain and increases anxiety—reported investigators at the State University of New York Downstate Medical Center. The sci-entists say this discovery could lead to new treat-ments for teen depres-sion and mental illness.

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Study participants “elected” George W. Bush’s modifi ed face (left) rather than John Kerry’s (right).

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