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Fear, erotica, and temporary blindness
November/December 2005
by Trey Popp '97
Graphic depictions of violence and sex have been blamed for everything from high crime rates to teenage pregnancy. But a pair of recent psychological experiments indicate that when it comes to racy pictures, the Victorians may have been right all along: they can make you go blind. Well, temporarily.
For a study in the August issue of the Psychonomic Bulletin & Review, Yale psychologists Steven Most, Marvin Chun, and David Widders, along with David Zald of Vanderbilt University, asked subjects to complete a straightforward task. They were to view a sequence of several hundred pictures, each of which appeared for one-tenth of a second on a computer monitor, and pick out “target” images of landscapes or buildings. Sprinkled through the series of emotionally neutral pictures were several that depicted emotionally disturbing sights, such as a knife pressed against a woman’s neck or a gruesomely flayed hand. These images upset participants enough to momentarily blind them to the pictures immediately following: when a target image appeared within one-fifth of a second after a disturbing image, subjects' accuracy rates fell from 85 to 71 percent. (Readers can take a version of the test at http://exploration.vanderbilt.edu/news/news_rubberneck.htm.) In an as yet unpublished study, Most substituted erotic pictures for disturbing ones. The result was the same.
“People’s attention seems to linger over the emotional image, even after it has passed,” Most says. “One result is that competing stimuli may fail to reach awareness.” He has dubbed the phenomenon “attentional rubbernecking,” comparing it to the way drivers slow down and peer into the wreckage of car accidents.
While disturbing images have long been considered special in their ability to distract attention, Most’s follow-up study suggests that other kinds of pictures may be equally distracting—and for the same reason. For example, people generally find erotic pictures pleasing. And yet, since participants reacted to them in the same way, Most hypothesizes that any image that evokes an intense emotion—good or bad—has the potential to stop us in our tracks.
Neuroimaging evidence suggests that a brain structure called the amygdala is heavily involved in what Most terms the “information bottleneck.” The amygdala makes many connections to other areas of the brain, some of which, such as the frontal and parietal lobes, are involved in the process of paying attention. It also plays a role in processing emotions. Most thinks this area “gets stuck on the emotional information, and we are temporarily unable to reorient attention to other things.”
Could momentary blindness have any evolutionary advantage? Most observes that closely interlinked emotion and attention systems could allow threatening information to be quickly prioritized—giving human beings a jump on predators. And in selecting a sexual mate, a flash of nudity certainly merits a bit of extra attention.
Gene swapping
by Jessica Ruvinsky '95
Mice and men share 99 percent of their genes. So much the worse for the mouse. Scientists have begun work on a dictionary of the human genome—and they’re building it out of mice.
With the help of a so-called “jumping” gene from the cabbage looper moth, scientists from Yale and from Fudan University in China are now able to break genes at will in mice and other vertebrates. The ability to tinker efficiently with the genetics of higher organisms is a breakthrough that will reveal the functions of genes and may also help advance gene therapy for diabetes, AIDS, and other ailments. The discovery is reported in the August 12 issue of the journal Cell.
Jumping genes, more formally known as transposons, are naturally occurring bits of DNA that move themselves around the genome. (The kernels of Indian corn change color because of transposons.) Since 1982, geneticists have been working with transposons in fruit flies to find out what individual genes do—taking advantage of the fact that a transposon landing in the middle of a working gene breaks it. The jumping gene system “provides a tremendous tool,” says Tian Xu, professor and vice chair of genetics at Yale’s School of Medicine. “By looking at what goes wrong, we can understand what the gene we’ve tampered with normally does.”
Scientists had searched in vain for 30 years for a transposon that they could easily manipulate in vertebrates. Xu’s team tried a long shot: a moth transposon whimsically named piggyBac.
Xu has now shown that piggyBac can remain stable in human and mouse cell lines and through five generations of mice, a discovery that has considerable promise for both basic and applied science. Over the last three decades, scientists have elucidated the functions of only ten percent of the mouse genome. In the next three years, Xu and colleagues at Fudan plan to use piggyBac to determine the remaining 90 percent.
Equally important, the transposon can also carry novel genes into the genome. This ability has enabled Xu and his team to put human tumor-suppressing genes into mice to learn how tumors grow and how they may be stopped.
The simplest sex
by Bruce Fellman
Birds, bees, and educated fleas do it—and so do placozoans. In the October 17 online early edition of the Proceedings of the National Academy of Sciences, Ana Signorovitch and colleagues showed that these sugar-grain-sized multicellular invertebrates are the simplest free-living organisms that have sex.
While the creatures typically reproduce by splitting in two, scientists had suspected that placozoans might also engage in sex. But such activity by extremely small organisms is not easy to spot. “Some animals only reproduce sexually once a year, and others have cryptic sex,” says Signorovitch, an ecology and evolutionary biology graduate student.
The researchers examined the DNA sequences of seven genes in the offspring of ten placozoans. The pattern of mutations and diversity they observed could only have been produced, says Signorovitch, “by the weaving together of genetic lineages that is characteristic of sex.”
Ancient life in 3-D
by Bruce Fellman
Nondescript rocks from Herefordshire, England, most of them no bigger than a baseball, are turning out to be one of the most important fossil finds in recent history. The Herefordshire fossils, formed by an unusual geological event, reveal the soft tissues of many different kinds of ancient invertebrates—structures that for most fossil animals had been only a matter of conjecture.
In the latest paper on the find, published in the August 18 issue of Nature, paleontologist Derek Briggs and his colleagues in England describe the internal anatomy of a 425-million-year-old brachiopod, a clam-like marine organism. (Brachiopods, once extremely abundant, survive today in smaller numbers.) The team has previously described the soft tissues of a sea spider and a tiny crustacean that is the earliest known definitely male animal; they will soon report on the oldest documented larval barnacle.
The fossils are all from an ecological community of animals that lived on the seafloor in the Silurian period, about 600 feet below the ocean surface. A volcanic explosion buried the community in fine ash. When the animal’s flesh decayed, calcite filled in the void that was left, preserving the shape of the tissues. “This gives you a mineral replica of the specimen, right down to the tiniest spines and bumps,” says Briggs.
To capture that detail, the scientists developed a method of grinding down each fossil in ultra-thin layers and taking a picture as each new layer was exposed. The process, which can take several months, destroys the fossil but produces a three-dimensional computer portrait of tissue structures never before observed in ancient organisms.
The brachiopod portrait reveals the animal’s body—in particular its feeding apparatus. Because it also shows several smaller brachiopods anchored to the shell, it provides a glimpse into the makeup of a Silurian ecosystem. “The geological record,” says Briggs, “occasionally provides us with extraordinary windows onto ancient life.”
Good news for Rolex?
by Trey Popp '97
After Hurricane Katrina devastated New Orleans, Americans donated more than $1 billion to the relief effort. Although storm victims were the prime beneficiaries, that outpouring of charity may also have been good news for Rolex retailers and purveyors of vintage Bordeaux. That’s the implication of a study by Ravi Dhar, a marketing professor at the School of Management, and Uzma Khan, a business school professor at Carnegie Mellon. In research to be published in the Journal of Marketing Research, the researchers found that consumers who feel they’ve been altruistic are more likely to splurge on luxury goods.
In one experiment, they asked participants to select a charity organization for which they would willingly volunteer three hours per week. Later, they asked the same people, plus another group of subjects, to choose between buying a pair of designer jeans and a vacuum cleaner, assuming that they had been planning to buy both but could only afford one. Contemplating community service made people twice as likely to choose the jeans. A second study swapped the time commitment for a hypothetical cash donation, and prompted subjects to choose between two pairs of sunglasses, one of which was “more expensive and frivolous.” The results were nearly identical: charitable intentions acted as a license to indulge.
Dhar, who directs SOM’s Center for Customer Insights, says that the “licensing effect” is strongest when people are not conscious of a relationship between successive choices. What’s more, simply thinking about acting altruistically seems to be enough to justify a splurge. “Just saying, ‘I’m the kind of person who volunteers,’ is almost as good as [actually spending] six hours serving food in a soup kitchen,” Dhar explains.
Yet there’s a downside to feeling altruistic: it may decrease the likelihood of subsequent good deeds. At the conclusion of one experiment, participants were given a chance to contribute some of their nominal fee to charity. Those who had already contemplated a hypothetical charitable act proved significantly less generous when the real thing came up.  |
