by Michael Marshall Low levels of mercury in the diet of male white ibises cause the birds to mate with each other rather than with females. As a result many of the females can't breed, and fewer chicks are produced. It's the first time a pollutant has been found to change an animal's sexual preference. Many chemicals can "feminise" males or reduce fertility, but males affected in these ways still prefer females. Mercury is extremely toxic, particularly in the form of methylmercury, which reduces breeding in wild birds by disrupting their parenting behaviours. To find out if it also affected mating, Peter Frederick of the University of Florida in Gainesville and Nilmini Jayasena of the University of Peradeniya, Sri Lanka, captured 160 young white ibises from south Florida. They gave them food laced with methylmercury and monitored them closely. The birds were split into four groups. One group ate food with 0.3 parts per million methylmercury, which most US states would regard as too high for human consumption. A second group got 0.1 ppm, and the third 0.05 ppm, a low dose that wild birds would be exposed to frequently. The fourth group received none. All three dosed groups had significantly more homosexual males than the control group. Male-male pairs courted, built nests together and paired off for several weeks. Higher doses increased the effect, with 55 per cent of males in the 0.3 ppm group affected. Male-male matings were responsible for 81 per cent of unproductive nests in the dosed groups. © Copyright Reed Business Information Ltd.

Keyword: Sexual Behavior; Neurotoxins
Link ID: 14729 - Posted: 12.02.2010

by Ed Yong IT WAS a bunch of robins that started it. The birds were locked in cages in Frankfurt, Germany, where they were being studied by biologist Hans Fromme. When the time came when they would normally migrate to sunny Spain, Fromme noticed they were becoming restless. What's more, they always tried to flee their cages in the same direction. This was in the late 1950s, and the thinking at the time was that migrating birds navigated using the sun, moon and stars. The cages were in a shuttered room, though, so the robins must have worked out which direction was which some other way. Magnetism was one possibility. The idea that migrating birds navigate across continents and oceans with the help of an internal compass had been suggested a century earlier by a Russian zoologist, but attempts to prove it had failed. That changed in 1966, when zoologist Wolfgang Wiltschko showed that the direction in which the robins attempted to escape could be changed by powerful magnets. His work suggested that most birds can sense the Earth's magnetic field, although many of his peers refused to believe it. "You don't want a stupid little bird doing something you don't do", says Roswitha Wiltschko of the University of Frankfurt, who together with her husband Wolfgang has been studying this ability for four decades. Their studies and others have proved the sceptics utterly wrong; we now know that a wide array of animals, from beetles to bats, rely on the Earth's magnetic field to help them navigate. © Copyright Reed Business Information Ltd.

Keyword: Animal Migration
Link ID: 14728 - Posted: 12.02.2010

by Carrie Arnold Chilling out might be the key to losing the weight you gained over Thanksgiving. New research shows that dieting makes the brain more sensitive to stress and the rewards of high-fat, high-calorie treats. These brain changes last long after the diet is over and prod otherwise healthy individuals to binge eat under pressure. Most research on weight loss has focused on tweaking appetite regulation—helping people eat less, get full faster, and have fewer cravings. But once we lose weight, we have trouble keeping it off. Even weight-loss surgery doesn't always help people maintain their more svelte physiques. Maybe, thought Tracy Bale, a neuroscientist at the University of Pennsylvania, the problem is stress. Stress causes the body to release the hormone cortisol, which fuels the blood with energy in the form of sugar, enabling us to flee from potential dangers. Over time, high stress levels lead to chronically elevated cortisol levels that can cause increased appetite and weight gain. Bale and her co-authors hypothesized that dieting leaves people more susceptible to the chronic stresses of everyday life, making even the strongest dieter yearn for a pint of ice cream or a hot, cheesy pizza. Although one hot fudge sundae won't cause significant weight gain, persistent stress could lead to a pattern of binge or comfort eating that undoes previous weight loss. © 2010 American Association for the Advancement of Science.

Keyword: Obesity; Stress
Link ID: 14727 - Posted: 12.02.2010

David Stock It's a cold London evening, and I've arranged to meet a friend. We're ostensibly heading to the cinema, but exactly where, or to see what, neither of us yet know. After wandering the back streets of Ladbroke Grove, guided on our way by polite yet impersonal men in white coats, we arrive at a grandiose and eerie mansion. We're robed in standard-issue medical gowns and ushered inside to collect our "prescriptions" of alcoholic or non-alcoholic medicine, then left to shuffle aimlessly down non-descript whitewashed corridors, afraid to make eye contact with any of the two hundred or so other "residents". By this point you'd be forgiven for thinking that New Scientist has finally noted my erratic behaviour and put word to my psychiatrist, and for a moment I might have agreed. Locked inside the walls of what purports to be The Oregon State Hospital, I am experiencing what it might be like to be detained for psychiatric assessment. This is Secret Cinema, an environment in which to experience film rather than just watch it. The film is One Flew Over the Cuckoo's Nest, of course. My initial anxiety subsides and I begin to enjoy the madness of my surroundings. "Spiders...do you see the spiders?" one inmate asks. "No," I reply. "They're like communists, everywhere," he says, pointing. When I ask what he means he responds: "I'm tired." At every turn I am met with fresh strangeness, from maniacal goose heads, to a choir of angelic voices, urns of the cremated or an impromptu yoga therapy session. © Copyright Reed Business Information Ltd.

Keyword: Schizophrenia
Link ID: 14726 - Posted: 12.02.2010

By Laura Sanders A rose sniffed through a snotty nose may not smell so sweet. Enzymes in mice’s nasal mucus transform certain scents before the nose can detect them, a new study finds. The results, published December 1 in the Journal of Neuroscience, show that lowly mucus may feature prominently in the sense of smell. “It is completely unexpected that snot would play a potential role in changing how we perceive odors,” says neuroscientist Leslie Vosshall at Rockefeller University in New York City. “Most people and most scientists pay no attention at all to mucus.” But there’s more to mucus than what meets the nose: The thick goo that serves to lubricate the nose is teeming with proteins and protein-chopping enzymes. Some of these molecules are thought to catch smells and shuttle them to odor receptors in the nose. Other components may protect the body from toxic chemicals by chopping them up into less harmful pieces. But no one knew whether this chopping action had any effect on smell perception. In the new study, Ayumi Nagashima and Kazushige Touhara of the University of Tokyo added particular odorants to tiny amounts of mucus sucked out of a mouse’s nose and tested the resulting chemical composition of the mix. After five minutes of sitting in mucus, about 80 percent of almond-smelling benzaldehyde was converted into benzyl alcohol (a scent found in some teas and plants) and the odorless benzoic acid. Inactive enzymes in boiled mucus couldn’t do this odor conversion, the team found. © Society for Science & the Public 2000 - 2010

Keyword: Chemical Senses (Smell & Taste)
Link ID: 14725 - Posted: 12.02.2010

By Alvaro Pascual-Leone We tend to believe that our brains work as well as they can. Thus, we assume that if you are good at math, it means that your brain is superior to the brains of those who find math more challenging. Of course, we have come to realize that people are better at some things than at others. Being better in math does not mean being smarter at everything. But we assume that, at least within a given domain, better behavioral performance implies superior brains, because we take it for granted that the brain is working as well as it can to optimize behavior. However, a growing number of instances in clinical neurology and a growing body of research in cognitive neuroscience reveal that this assumption is incorrect. (Many are discussed in “The Paradoxical Brain,” a new book edited by Narinder Kapur and coming out next year from Cambridge University Press.) For example, if the brain optimizes behavior, disruption of normal brain activity ought to lead to a loss of function, and never to enhancement. And yet, in some instances, disruption of brain activity with noninvasive transcranial magnetic stimulation or transcranial direct current stimulation -- both methods that use devices outside the skull to affect the workings inside -- can result in a paradoxical behavioral improvement. Take a recent example: In the November 23 issue of Current Biology, researchers led by Roi Cohen Kadosh of Oxford University report that noninvasive brain stimulation can promote the “number sense.” © 2010 Scientific American

Keyword: Attention; Laterality
Link ID: 14724 - Posted: 12.02.2010

Eating disorders are sending more U.S. children to hospital and pediatricians should be on the lookout for patients suspected of having a problem, according to a new report. Among children younger than 12 with eating disorders, hospitalizations jumped 119 per cent between 1999 and 2006, says the clinical report in Monday's edition of the American Academy of Pediatrics. It is estimated 0.5 per cent of adolescent girls in the United States have anorexia nervosa (self-starvation), and one to two per cent meet criteria for bulimia nervosa (bingeing and purging), the report said. Since eating disorders can affect any organ system, pediatricians should monitor patients for medical or nutritional problems, and ensure treatment such as medical care, mental-health treatment and nutritional intervention, the report's authors recommended. "Pediatricians are encouraged to advocate for legislation and policies that ensure appropriate services for patients with eating disorders, including medical care, nutritional intervention, mental-health treatment and care co-ordination," conclude report author Dr. David Rosen of the University of Michigan and his co-authors. There is an increasing recognition of eating disorders in males, who make up 10 per cent of all cases. The disorders are increasingly seen in children. © CBC 2010

Keyword: Anorexia & Bulimia
Link ID: 14723 - Posted: 11.30.2010

By ABIGAIL ZUGER, M.D. Who has seen the mind? Neither you nor I — nor any of the legions of neuroscientists bent on opening the secrets of that invisible force, as powerful and erratic as the wind. The experts are definitely getting closer: the last few decades have produced an explosion of new techniques for probing the blobby, unprepossessing brain in search of the thinking, feeling, suffering, scheming mind. But the field remains technologically complicated, out of reach for the average nonscientist, and still defined by research so basic that the human connection, the usual “hook” by which abstruse science captures general interest, is often missing. Carl Schoonover took this all as a challenge. Mr. Schoonover, 27, is midway through a Ph.D. program in neuroscience at Columbia, and thought he would try to find a different hook. He decided to draw the general reader into his subject with the sheer beauty of its images. So he has compiled them into a glossy new art book. “Portraits of the Mind: Visualizing the Brain From Antiquity to the 21st Century,” newly published by Abrams, includes short essays by prominent neuroscientists and long captions by Mr. Schoonover — but its words take second place to the gorgeous imagery, from the first delicate depictions of neurons sketched in prim Victorian black and white to the giant Technicolor splashes the same structures make across 21st-century LED screens. Copyright 2010 The New York Times Company

Keyword: Miscellaneous
Link ID: 14722 - Posted: 11.30.2010

Jeremy Laurance Why do beautiful people have more daughters? Because beauty is more important for a woman than a man, according to evolutionary psychologist Satoshi Kanazawa. Why are most suicide bombers Muslim? Because they don't get enough sex. Why are liberals more intelligent than conservatives? Because liberalism is "evolutionarily novel." The London School of Economics researcher and author of Ten Politically Incorrect Truths about Human Nature is accustomed to defending his provocative assertions against outraged critics. He acknowledges that some of his ideas may seem "immoral, contrary to our ideals or offensive". But he insists they are true and supported by scientific evidence that he has continued to collect since his book was published in 2007. "Like it or not, human nature is simply not politically correct," he says. Now, in a study to be published in Reproductive Sciences, he has adduced new evidence for what he describes as one of the most celebrated principles in evolutionary biology which explains why attractive people have more female children. So how does the research stack up? 1 Beautiful people have more daughters Known as the Trivers-Willard hypothesis this states that if parents have any traits they can pass on to their children and that will be better for one sex than the other, they they will have more children of that sex. ©independent.co.uk

Keyword: Evolution; Sexual Behavior
Link ID: 14721 - Posted: 11.30.2010

By DUFF WILSON Two prominent authors of a 1999 book teaching family doctors how to treat psychiatric disorders provided acknowledgment in the preface for an “unrestricted educational grant” from a major pharmaceutical company. From the book “Recognition and Treatment of Psychiatric Disorders: A Psychopharmacology Handbook for Primary Care.” But the drug maker, then known as SmithKline Beecham, actually had much more involvement than the book described, newly disclosed documents show. The grant paid for a writing company to develop the outline and text for the two named authors, the documents show, and then the writing company said it planned to show three drafts directly to the pharmaceutical company for comments and “sign-off” and page proofs for “final approval.” “That doesn’t sound unrestricted to me,” Dr. Bernard Lo, a medical ethicist and chairman of an Institute of Medicine group that wrote a 2009 report on conflicts of interest, said after reviewing the documents. “That sounds like they have ultimate control.” The 269-page book, “Recognition and Treatment of Psychiatric Disorders: A Psychopharmacology Handbook for Primary Care,” is so far the first book among publications, namely medical journal articles, that have been criticized in recent years for hidden drug industry influence, colloquially known as ghostwriting. “To ghostwrite an entire textbook is a new level of chutzpah,” said Dr. David A. Kessler, former commissioner of the Food and Drug Administration, after reviewing the documents. “I’ve never heard of that before. It takes your breath away.” Copyright 2010 The New York Times Company

Keyword: Depression; Schizophrenia
Link ID: 14720 - Posted: 11.30.2010

By NED BLOCK In “Self Comes to Mind,” the eminent neurologist and neuroscientist Antonio Damasio gives an account of consciousness that might come naturally to a highly caffeinated professor in his study. He emphasizes wakefulness, self-awareness, reflection, rationality, “knowledge of one’s own existence and of the existence of surroundings.” That is certainly one kind of consciousness, what one might call self-consciousness. But there is also a different kind, as anyone who knows what it is like to have a headache, taste chocolate or see red can attest. Self-consciousness is a sophisticated and perhaps uniquely human cognitive achievement. Phenomenal consciousness by contrast — what it is like to experience — is something we share with many animals. A person who is drunk or delirious or dreaming can be excruciatingly conscious without being wakeful, self-aware or aware of his surroundings. The term “conscious” was first introduced into academic discourse by the Cambridge philosopher Ralph Cudworth in 1678, and by 1727, John Maxwell had distinguished five senses of the term. The ambiguity has not abated. Damasio’s distinctive contributions in “Self Comes to Mind” are an account of phenomenal consciousness, a conception of self­consciousness and, most controversially, a claim that phenomenal consciousness is dependent on self-consciousness. Copyright 2010 The New York Times Company

Keyword: Attention
Link ID: 14719 - Posted: 11.30.2010

By Amanda Schaffer Last week, researchers at the University of Colorado published a psych experiment that seems almost too good to be true. They showed that two 15-minute writing exercises, administered to an intro physics class early in the semester, could substantially boost the scores of female students. Even more curious: the exercises had nothing to do with physics. Instead, students were asked to write about things that mattered to them, like creativity or relationships with family and friends. How could a few paragraphs on personal values translate into enduring better mastery of pulleys and frictionless planes? When it comes to math and science classes, women can be subtly hampered by negative stereotypes about their gender. This is the idea of stereotype threat, advanced by psychologists Joshua Aronson and Claude Steele, and now solidly established, as I've written in Slate before. Stereotype threat can roar into action when members of any stereotyped group are primed to think about belonging to it—in other words, when women focus on being female or African-Americans on being black. It causes performance problems, but stereotype threat can also be countered, often in simple ways. As the Colorado writing exercises show, getting women to focus on things they care about can buck them up. The lesson is that small doses of affirmation can do a lot of good. Here's what we know about how stereotype threat works: In the 1990s, researchers found that women taking a math exam who were told that the test had "shown gender differences in the past" scored lower than other women with equivalent math backgrounds. Similarly, women asked to watch commercials in which ditzy ladies gushed about brownie mix afterward expressed less interest in quantitative pursuits. Stereotype threat is a universal offender: It can sabotage white men on the basketball court or men more broadly on a test of social sensitivity. © Copyright 2010 Washington Post.Newsweek Interactive Co. LLC

Keyword: Sexual Behavior
Link ID: 14718 - Posted: 11.30.2010

by Jennifer Carpenter In F. Scott Fitzgerald's short story, "The Curious Case of Benjamin Button," an old man gets younger with each passing day, a fantastic concept recently brought to life on film by Brad Pitt. In a lab in Boston, a research team has used genetic engineering to accomplish something similarly curious, turning frail-looking mice into younger versions of themselves by stimulating the regeneration of certain tissues. The study helps explain why certain organs and tissues break down with age and, researchers say, offers hope that one day such age-related deterioration can be thwarted and even reversed. As we age, many of our cells stop dividing. Our organs, no longer able to rejuvenate themselves, slowly fail. Scientists don't fully understand what triggers this, but many researchers suspect the gradual shrinking of telomeres, the protective DNA caps on the end of chromosomes. A little bit of telomere is lost each time a cell divides, and telomerase, the enzyme that maintains caps, isn't typically active in adult tissues. Another piece of evidence: People with longer telomeres tend to live longer, healthier lives, whereas those with shorter telomeres suffer more from age-related diseases, such as diabetes, Alzheimer's, and heart disease. Several years ago, Ronald DePinho, molecular biologist and director of the Belfer Institute of the Dana-Farber Cancer Institute, and colleagues at Harvard Medical School in Boston genetically engineered mice to lack a working copy of the telomerase gene. The animals died at about 6 months—that's young for mice, which usually live until they are about 3 years old—and seemed to age prematurely. At an early age, their livers and spleens withered, their brains shrank, and they became infertile. By early adulthood, these mice exhibited many of the maladies seen in 80-year-old humans. © 2010 American Association for the Advancement of Science.

Keyword: Alzheimers
Link ID: 14717 - Posted: 11.30.2010

By Susan Milius Not to reopen any emotional scars from Thanksgiving dinner, but an unusual study of an animal social network suggests that ending up as the butt of unfriendly interactions could be in part inherited. The study, in yellow-bellied marmots, gives the first look beyond people at what facets of social relationships might have genetic components, says coauthor Daniel Blumstein of UCLA. It’s receiving incoming social attention, particularly in grouchy interactions, that showed a small but intriguing genetic influence, Blumstein says. Aspects of initiating interactions in a network, whether to dish out snubs or snuggles, showed no evidence of heritability, according to the paper posted online November 29 in the Proceedings of the National Academy of Sciences. “I am completely blown away by this paper,” says James Fowler, professor of medical genetics and political science at the University of California, San Diego. In human networks, he and his colleagues have found the marmotlike pattern of heritability in aspects of received social ties but not in initiated ones. Fowler had suspected that the asymmetry in people came from a quirk of limiting the number of friends in the study. Marmots didn’t have that limitation though, he says, “so the idea that there may be something systematic here between species is extremely interesting.” Marmots don’t have Facebook yet, but animals living among clusters of burrows in Colorado do interact enough for observers to plot networks with each marmot as a node. An exchange might be friendly, such as a marmot grooming a neighbor or settling down tranquilly nearby. Or a social interaction might go sour, with one marmot nipping or chasing another. © Society for Science & the Public 2000 - 2010

Keyword: Aggression; Genes & Behavior
Link ID: 14716 - Posted: 11.30.2010

Analysis by Tim Wall Female cichlid fish seem to want heroes not zeros, according to researchers at Stanford University. The female fish prefer pugnacious piscine pugilists. The African cichlid females' brains showed signs of anxiety after witnessing a preferred mate lose a fight with another fish. At the same time, seeing their chosen male beat down his opponent resulted in increased activity in parts of the female's brain associated with reproduction and pleasure. Humans might show some of those same responses, because the brain areas involved in the cichlid's response are similar and perform comparable functions in humans, fish, and in fact all other vertebrates, said Russ Fernald, a professor of biology at Stanford in a press release. "It is the same as if a woman were dating a boxer and saw her potential mate get the crap beat out of him really badly," Julie Desjardins, a postdoctoral biology researcher and lead author of the paper published in Proceedings of the National Academy of Sciences. "She may not consciously say to herself, 'Oh, I'm not attracted to this guy anymore because he's a loser.' But her feelings might change anyhow." In humans the subconscious change could result from failure in any competitive situation, such as losing a game or failing to get a promotion, not just physical violence, said Desjardins. Also, human males might feel a similar loss of interest if a female failed in a competition. © 2010 Discovery Communications, LLC.

Keyword: Sexual Behavior; Aggression
Link ID: 14715 - Posted: 11.30.2010

Ed Yong There’s a chemical that can subtly shift your childhood memories of your own mother. In some people, it paints mum in a more saintly light, making them remember her as closer and more caring. In others, the chemical has a darker influence, casting mum as a less caring and more distant parent. All of this becomes heavily ironic when you consider that the chemical in question – a hormone called oxytocin – is often billed as the “hormone of love”, and even marketed as “Liquid Trust”. As a new study shows, the reality is much more complicated. Describing oxytocin as the “hormone of love” is like describing a computer as a “writing tool” – it does other things too, some of which aren’t pleasant. Oxytocin is a versatile actor, whose resume includes all sorts of jobs in sex, reproduction, social behaviour and emotions. It can increase trust among people and make them more cooperative (this works in meerkats, too). It can increase the social skills of autistic people. It’s released during orgasm. It affects lactating breasts, contracting wombs and the behaviour of sheep mothers towards their newly born lambs. The list goes on: drug addiction, generosity, depression, empathy, learning, memory. Despite these many roles, oxytocin is often reduced to a misleading label. While “hormone of love” may be great for catchy headlines and compelling marketing slogans, they are ultimately misleading. Jennifer Bartz from the Mount Sinai School of Medicine has found that oxytocin can have completely opposite effects on the way people behave, depending on how they view their relationships to other people. © 2010, Kalmbach Publishing Co.

Keyword: Hormones & Behavior; Emotions
Link ID: 14714 - Posted: 11.30.2010

By Karen Weintraub A German researcher recently identified a gene that appears to promote generosity. American scientists are finding that being big-hearted may trigger the brain’s pleasure centers. And Jeff Bell and Jared Douglas Kant are convinced that helping others cope with obsessive-compulsive behaviors made the difference in their own treatment for the disorder. Giving, it seems, is not just a seasonal thing. Altruism appears to be innate, and researchers, doctors, and patients say the act of giving or helping offers deep psychological benefits. “I think it’s a very human phenomenon,’’ said Dr. Helen Riess, an associate professor of psychiatry at Harvard Medical School. Evolution has wired the human brain to promote helpfulness, she said, something like “survival of the nicest.’’ “If we didn’t help others through altruism, we wouldn’t have as many people around,’’ said Riess, also the director of empathy research and training in the department of psychology at Massachusetts General Hospital. “If our village were attacked by invaders, individuals would just get into a hole and save themselves. But instead, they work together. Mutual aid sustains species.’’ The brain responds to such cooperative behavior by releasing the feel-good chemical dopamine, Riess said, and helping someone else improve — or even just watching an improvement — makes us, as empathetic beings, feel better. © 2010 NY Times Co.

Keyword: Emotions; Drug Abuse
Link ID: 14713 - Posted: 11.29.2010

A gene therapy technique which aims to ease memory problems linked to Alzheimer's Disease has been successfully tested in mice. US scientists used it to increase levels of a chemical which helps brain cells signal to each other. This signalling is hindered in Alzheimer's Disease, the journal Nature reported. The Alzheimer's Research Trust said the study suggested a way to keep nerve cells in the brain communicating, Ageing populations in many countries around the world mean that Alzheimer's disease and other forms of dementia are set to increase. Researchers at the Gladstone Institute of Neurological Disease in San Francisco believe that boosting the brain chemical, a neurotransmitter called EphB2, could help reduce or even prevent some of the worst effects of the condition. Their research suggests that the chemical plays an important role in memory, and is depleted in Alzheimer's patients. One of the most noticeable features about the brains of Alzheimer's patients is the build-up of "plaques" of a toxic protein called amyloid. Over time this leads to the death of brain cells. BBC © MMX

Keyword: Alzheimers; Genes & Behavior
Link ID: 14712 - Posted: 11.29.2010

By Maggie Koerth-Baker A crooked tooth. That funky mole. A pimple on your chin. When you stare into the mirror and pick apart the little imperfections, you're doing more than being too hard on yourself. In fact, that behavior—understanding that your reflection is you, and seeing how you differ from other people—is often taken as a demonstration of some complex cognitive gymnastics that not all species can pull off. Since the 1970s psychologists have used mirrors to search for signs of self-awareness in both humans and animals. Along the way, they came to believe that humans were almost universally able to pass a mirror-based self-recognition test by 24 months of age. But a 2004 study published in Child Development called that idea into question. Researchers found the widely accepted finding only applied to kids from Western nations, where most of the previous studies had been done. Now, a study published September 9 in The Journal of Cross-Cultural Psychology is reinforcing that idea and taking it further. Not only do non-Western kids fail to pass the mirror self-recognition test by 24 months—in some countries, they still are not succeeding at six years old. What does it mean? Are kids in places like Fiji and Kenya really unable to figure out a mirror? Do these children lack the ability to psychologically separate themselves from other humans? Not likely. Instead researchers say these results point to long-standing debates about what counts as mirror self-recognition, and how results of the test ought to be interpreted. © 2010 Scientific American,

Keyword: Attention; Evolution
Link ID: 14711 - Posted: 11.29.2010

Anne Trafton, MIT News Office Neuroscientists at MIT and Harvard have made the surprising discovery that the brain sees some faces as male when they appear in one area of a person’s field of view, but female when they appear in a different location. The findings challenge a longstanding tenet of neuroscience — that how the brain sees an object should not depend on where the object is located relative to the observer, says Arash Afraz, a postdoctoral associate at MIT’s McGovern Institute for Brain Research and lead author of a new paper on the work. “It’s the kind of thing you would not predict — that you would look at two identical faces and think they look different,” says Afraz. He and two colleagues from Harvard, Patrick Cavanagh and Maryam Vaziri Pashkam, described their findings in the Nov. 24 online edition of the journal Current Biology. In the real world, the brain’s inconsistency in assigning gender to faces isn’t noticeable, because there are so many other clues: hair and clothing, for example. But when people view computer-generated faces, stripped of all other gender-identifying features, a pattern of biases, based on location of the face, emerges. The researchers showed subjects a random series of faces, ranging along a spectrum of very male to very female, and asked them to classify the faces by gender. For the more androgynous faces, subjects rated the same faces as male or female, depending on where they appeared.

Keyword: Vision; Sexual Behavior
Link ID: 14710 - Posted: 11.29.2010