WASHINGTON— There really may be something different about the brains of math-heads. Mathematically gifted teens did better than average-ability teens and college students on tests that required the two halves of the brain to cooperate, as reported in the April issue of Neuropsychology, published by the American Psychological Association (APA). In the study, a joint effort of psychologists at the U.S. Army Research Institute for the Behavioral and Social Sciences at Fort Benning, Ga. and the University of Melbourne, Australia, researchers studied 60 right-handed males: 18 mathematically gifted (averaging nearly 14 years in age), 18 of average math ability (averaging just over 13), and 24 college students (averaging about 20). Math giftedness seems to favor boys over girls, appearing an estimated six to 13 times more often. It’s not known why but prenatal exposure to testosterone is suspected to be one influence due to its selective benefit to the right half of the brain. The gifted boys were recruited from a Challenges for Youth-Talented program at Iowa State University. Whereas the average Scholastic Aptitude Test (SAT) math score for college-bound high-school seniors is 500 (out of 800), the mathematically gifted boys’ average SAT math score in middle school was 620. © 2004 American Psychological Association

Related chapters from BP6e: Chapter 19: Language and Hemispheric Asymmetry
Related chapters from MM:Chapter 15: Language and Our Divided Brain
Link ID: 5263 - Posted: 06.24.2010

WASHINGTON— There really may be something different about the brains of math-heads. Mathematically gifted teens did better than average-ability teens and college students on tests that required the two halves of the brain to cooperate, as reported in the April issue of Neuropsychology, published by the American Psychological Association (APA). In the study, a joint effort of psychologists at the U.S. Army Research Institute for the Behavioral and Social Sciences at Fort Benning, Ga. and the University of Melbourne, Australia, researchers studied 60 right-handed males: 18 mathematically gifted (averaging nearly 14 years in age), 18 of average math ability (averaging just over 13), and 24 college students (averaging about 20). Math giftedness seems to favor boys over girls, appearing an estimated six to 13 times more often. It’s not known why but prenatal exposure to testosterone is suspected to be one influence due to its selective benefit to the right half of the brain. The gifted boys were recruited from a Challenges for Youth-Talented program at Iowa State University. Whereas the average Scholastic Aptitude Test (SAT) math score for college-bound high-school seniors is 500 (out of 800), the mathematically gifted boys’ average SAT math score in middle school was 620. © 2004 American Psychological Association

Related chapters from BP6e: Chapter 19: Language and Hemispheric Asymmetry
Related chapters from MM:Chapter 15: Language and Our Divided Brain
Link ID: 5262 - Posted: 06.24.2010

Kerri Smith 'Southpaw', 'goofy', or just plain 'lefty' are some of the many names that left-handers have been called. In certain societies, the aversion can go so far that some left-handers are forced to write with their right hand, regardless of their natural tendencies. Now, a study of such 'converted' left-handers has found that the way their brains are organized, and how hard particular regions work, changes as a result of this switch. Some areas of the brain continue to look like those of a practising lefty, whereas other areas switch to the patterns of a righty, the research reveals. "The question now is, 'do converts suffer because of this extra attention that they exert?'," says Stefan Klöppel of University College London, who led the work. The answer to that is as yet unknown. The hand used to write with is generally controlled by the opposite side of the brain — in right-handed people, movement-related areas on the left side of the brain are more active when they move the fingers of their right hand. But converting from being left-handed to right-handed doesn't simply move brain activity to the other half of the brain, Klöppel and his colleagues found. ©2007 Nature Publishing Group

Related chapters from BP6e: Chapter 19: Language and Hemispheric Asymmetry
Related chapters from MM:Chapter 15: Language and Our Divided Brain
Link ID: 10502 - Posted: 06.24.2010

This column is brought to you care of what the Australians call a "shonky molly-dooker." Not so much a left-hander as a leftish-hander. What I do is write and draw with my left hand but approach everything else the – ha-ha – right way. This anomaly has led me, over the years, to pay more than passing attention to what you might call the science of left-handedness. If it can find a believable explanation for why shonky molly-dookerness should persist in human evolution, maybe an extension of that reasoning will tell me something essential about myself. That's why my eyes opened when I started to read a recent paper published in the journal Brain by Sandra Witelson and her colleagues at McMaster University. They were interested in coming up with an as accurate as possible measure of the relationship of brain size to braininess. They approached people dying of cancer in a Hamilton hospital and asked whether they would take IQ tests. Afterwards, the scientists did an autopsy on the brains to see how volume compared with IQ score. The test group was divided between men and women and right- and left-handers. The handedness was measured because previous evidence has accumulated that there might be relationship between handedness and brain size. © CBC 2006

Related chapters from BP6e: Chapter 1: Biological Psychology: Scope and Outlook; Chapter 19: Language and Hemispheric Asymmetry
Related chapters from MM:Chapter 1: An Introduction to Brain and Behavior; Chapter 15: Language and Our Divided Brain
Link ID: 8400 - Posted: 06.24.2010

(Bethesda, MD) – The phrase, “the right hand doesn’t know what the left hand is doing,” has its roots in a passage of the Bible (Matthew 6:3). If there is truth to this old saying, the reasons may have as much to do with the way the brain obtains information from the arms as it does from the observations of ancient scribes. Most individuals are either left- or right-handed. How the skills they have learned from the dominant arm (or hand) are transferred to the non-dominant arm have long intrigued physiologists and neurologists. Copyright © 2003, The American Physiological Society,

Related chapters from BP6e: Chapter 19: Language and Hemispheric Asymmetry; Chapter 11: Motor Control and Plasticity
Related chapters from MM:Chapter 15: Language and Our Divided Brain; Chapter 5: The Sensorimotor System
Link ID: 3577 - Posted: 06.24.2010

by Greg Miller For most people, it's trivially easy to reach for an object with one hand and keep the other hand still. But in people with a rare inherited condition, when the brain orders one hand to move, the other hand performs the same movement at the same time. Now scientists think they've found a gene mutation that's responsible for this "mirror movement" disorder. The find could yield insights into how the brain gets wired during development. The discovery is exciting, says Susan Ackerman, a neurogeneticist at the Jackson Laboratory in Bar Harbor, Maine, who was not involved in the research. The mutation affects a receptor for a signaling molecule called netrin that is involved in one of the best-studied pathways in developmental neuroscience, she says, but all of that work has been done in animals such as mice, worms, and fruit flies. "To my knowledge, this is the first indication that it's really important in humans too." Mirror movements are a rare and puzzling phenomenon. Babies often exhibit mirror movements in which, for example, an intentional grasping movement with one hand or a kick with one leg is accompanied by a similar involuntary movement by the other side. But these anomalies almost never persist into adulthood, says Guy Rouleau, a neurologist at the University of Montreal in Canada. However, Rouleau and colleagues have recently identified two families—one in Iran and one in Canada—in which some individuals exhibit mirror movements as adults. © 2010 American Association for the Advancement of Science.

Related chapters from BP6e: Chapter 11: Motor Control and Plasticity; Chapter 19: Language and Hemispheric Asymmetry
Related chapters from MM:Chapter 5: The Sensorimotor System; Chapter 15: Language and Our Divided Brain
Link ID: 14027 - Posted: 06.24.2010

By Bruce Bower CHICAGO — Give the chimpanzees living at Uganda’s Toro-Semliki Wildlife Reserve a hand for having the mental moxie to dig water-collection holes along the edge of a river that flows only during rainy months. In fact, give them two hands, because wells dug by these chimps show no evidence of having been fashioned by either right-handers or left-handers, according to anthropologist Linda Marchant of Miami University in Oxford, Ohio. Evidence of ambidexterity in Semliki chimps counters a suggestion from other researchers, based largely on studies of captive animals, that chimps often favor one hand over the other when performing various tasks. If it exists, chimp handedness interests researchers because it may reflect an evolutionary move toward a brain organized more like that of people — with one hemisphere dominating over the other and prompting either right- or left-handedness —than has often been assumed. “We see no signs of handedness among the Semliki chimps, which appears to be the condition in the wild,” said anthropologist and study coauthor William McGrew of the University of Cambridge in England. Marchant presented her team’s new findings on April 3 at the American Association of Physical Anthropologists annual meeting. Rather than excluding hand preferences altogether among wild chimps, findings at Semliki indicate that chimps use both hands equally on physically demanding jobs, such as well digging, remarked Elizabeth Lonsdorf, director of the Lester E. Fisher Center for the Study and Conservation of Apes at Lincoln Park Zoo in Chicago. © Society for Science & the Public 2000 - 2009

Related chapters from BP6e: Chapter 19: Language and Hemispheric Asymmetry; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 15: Language and Our Divided Brain
Link ID: 12728 - Posted: 06.24.2010

By ANAHAD O’CONNOR Already burdened with the minor mishaps that arise from living in a world designed for righties, their lot in life seemed to worsen considerably in the 1980s, when a study argued that southpaws had several times the risk of chronic headaches — and immune disorders — as their right-handed counterparts. The reason, it was theorized, had something to do with variations in fetal brain development, though no precise explanation was given. But a raft of evidence now suggests that the migraine finding, though intriguing, was less fact than statistical artifact. A more extensive study published in March by German scientists examined a group of 100 patients who had received a diagnosis of migraine based on standards set by the International Headache Society. After finding no evidence of a link between handedness and migraines, the scientists pooled data from five other studies and conducted a meta-analysis. Still, there was no evidence of a relationship — a conclusion echoed by many similar studies. Several studies have also examined whether there is any relationship between left-handedness and increased risk of immune disorders. The findings are inconclusive. Proponents argue that fetal exposure to high levels of testosterone could be responsible, and they point out that left-handedness is more common in men than women. Critics say more research is needed. THE BOTTOM LINE Most studies have found that being left-handed does not increase the risk of migraines. Copyright 2008 The New York Times Company

Related chapters from BP6e: Chapter 19: Language and Hemispheric Asymmetry; Chapter 8: General Principles of Sensory Processing, Touch, and Pain
Related chapters from MM:Chapter 15: Language and Our Divided Brain; Chapter 5: The Sensorimotor System
Link ID: 11526 - Posted: 06.24.2010

Bruce Bower The concept of identity theft assumes an entirely new meaning for people with brain injuries that rob them of their sense of self—the unspoken certainty that one exists as a person in a flesh—bounded body with a unique set of life experiences and relationships. Consider the man who, after sustaining serious brain damage, insisted that his parents, siblings, and friends had been replaced by look-alikes whom he had never met. Everyone close to him had become a familiar-looking stranger. Another brain-injured patient asserted that his physicians, nurses, and physical therapists were actually his sons, daughters-in-law, and coworkers. He identified himself as an ice skater whom he had seen on a television program. The sense of "I" can also go partially awry. After a stroke had left one of her arms paralyzed, a woman reported that the limb was no longer part of her body. She told a physician that she thought of the arm as "my pet rock." Other patients bequeath their physical infirmities to phantom children. For instance, a woman blinded by a brain tumor became convinced that it was her child who was sick and blind, although the woman had no children. Copyright ©2006 Science Service.

Related chapters from BP6e: Chapter 19: Language and Hemispheric Asymmetry
Related chapters from MM:Chapter 15: Language and Our Divided Brain
Link ID: 8520 - Posted: 06.24.2010

By Anna Salleh, ABC Science Online — There may be more left-handed people than we realize, an international study has found. If we include the number of people who throw a ball, strike a match or use a pair of scissors with their left hand, the researchers say the world looks more of a left-handed place. Australian researcher Sarah Medland of the Queensland Institute of Medical Research in Brisbane and team publish the research in the current issue of the journal Laterality. Left-handed people face problems in a world where most things, from scissors to can-openers and computers to power tools, are designed for right-handers. In the past left-handers faced even greater problems. Some schoolchildren were forced, under threat of the strap, to write with their right hand, regardless of their natural tendency. Medland and team hoped to shed light on the contribution of cultural factors like this on the distribution of handedness. Copyright © 2004 Discovery Communications Inc.

Related chapters from BP6e: Chapter 19: Language and Hemispheric Asymmetry
Related chapters from MM:Chapter 15: Language and Our Divided Brain
Link ID: 6108 - Posted: 06.24.2010

Out of Left Field: Studies of chimpanzees finally give southpaws a fair shake By Jocelyn Selim At the Yerkes Regional Primate Research Center in Atlanta, a large chimpanzee named Winston is taking part in an unusually pleasant experiment. Using his left hand, he reaches over and grabs a length of PVC pipe from primatologist Bill Hopkins, then he uses his right to scoop out some peanut butter smeared inside. "Winston's a righty," Hopkins says, offering another piece of pipe to a smaller chimp hovering nearby. This one grabs the pipe with his right hand and digs out the peanut butter with his left. "That's Winston's younger brother," Hopkins says. Over the past 10 years, Hopkins's research has offered the first definitive proof that apes, like humans, have hand preferences: A third of the Yerkes chimpanzees are lefties and the rest are righties. But Winston and his brother point to an even more intriguing pattern: The younger the sibling, the more likely he or she is to be a lefty. And if handedness is clearly tied to birth order in chimps, it could throw a monkey wrench into theories of handedness in humans as well. Granted, those theories already have a lot of explaining to do. Among humans, lefties are more likely than righties to suffer from dyslexia, schizophrenia, stuttering, and other disorders. But lefties are also more likely to be Mensa members, musicians, and U.S. presidents (Bill Clinton, George Bush Sr., and Ronald Reagan are all left-handed). And al-though left-handedness runs in families—notably in Queen Elizabeth II, Prince Charles, and Prince William—more than two-thirds of all lefties are born to right-handed couples. Even identical twins often have opposite hand preferences. © Copyright 2002 The Walt Disney Company.

Related chapters from BP6e: Chapter 19: Language and Hemispheric Asymmetry
Related chapters from MM:Chapter 15: Language and Our Divided Brain
Link ID: 1199 - Posted: 06.24.2010

By Peter F. MacNeilage, Lesley J. Rogers and Giorgio Vallortigara The left hemisphere of the human brain controls language, arguably our greatest mental attribute. It also controls the remarkable dexterity of the human right hand. The right hemisphere is dominant in the control of, among other things, our sense of how objects interrelate in space. Forty years ago the broad scientific consensus held that, in addition to language, right-handedness and the specialization of just one side of the brain for processing spatial relations occur in humans alone. Other animals, it was thought, have no hemispheric specializations of any kind. Those beliefs fit well with the view that people have a special evolutionary status. Biologists and behavioral scientists generally agreed that right-handedness evolved in our hominid ancestors as they learned to build and use tools, about 2.5 million years ago. Right-handedness was also thought to underlie speech. Perhaps, as the story went, the left hemisphere simply added sign language to its repertoire of skilled manual actions and then converted it to speech. Or perhaps the left brain’s capacity for controlling manual action extended to controlling the vocal apparatus for speech. In either case, speech and language evolved from a relatively recent manual talent for toolmaking. The right hemisphere, meanwhile, was thought to have evolved by default into a center for processing spatial relations, after the left hemisphere became specialized for handedness. In the past few decades, however, studies of many other animals have shown that their two brain hemispheres also have distinctive roles. Despite those findings, prevailing wisdom continues to hold that people are different. Many investigators still think the recently discovered specializations of the two brain hemispheres in nonhumans are unrelated to the human ones; the hemispheric specializations of humans began with humans. © 1996-2009 Scientific American Inc.

Related chapters from BP6e: Chapter 19: Language and Hemispheric Asymmetry; Chapter 6: Evolution of the Brain and Behavior
Related chapters from MM:Chapter 15: Language and Our Divided Brain
Link ID: 12982 - Posted: 06.24.2010

By C. CLAIBORNE RAY Q. Is left-handedness less common in women? A. Studies of Western populations usually find that left-handedness is somewhat less common in women, but perhaps because left-handedness is hard to define, the difference varies by several percentage points. One large study in 1971 used a standard called the Edinburgh Handedness Inventory, which asks which hand is used for different tasks, and found that 90 percent of women were right-handed, as against 86 percent of men. But a smaller 1988 study using the same inventory found no significant difference by sex, and a large Internet study done for the BBC for another purpose found sex differences that varied by ethnic group. Anthropologists’ studies of traditional cultures in Africa and elsewhere found a wide range of differences, from no left-handed women at all to levels approximating those in Western studies. Some researchers have suggested that the trend for more men to be left-handed is not universal or may be affected by social norms, with left-handed men stubbornly clinging to left-handedness while left-handed women are more easily persuaded to join the majority. Copyright 2006 The New York Times Company

Related chapters from BP6e: Chapter 19: Language and Hemispheric Asymmetry; Chapter 12: Sex: Evolutionary, Hormonal, and Neural Bases
Related chapters from MM:Chapter 15: Language and Our Divided Brain; Chapter 8: Hormones and Sex
Link ID: 9175 - Posted: 06.24.2010

By C. CLAIBORNE RAY A. “In both humans and other mammals, as the body became more complex and reacted to environmental stressors, the brain developed in response to that,” said Dr. Philip E. Stieg, chief of neurosurgery at NewYork-Presbyterian Hospital/Weill Cornell. “We do not know what specific stimulus changed or caused a species that has a single brain lobe to evolve to have two hemispheres. It was probably a series of stimuli.” All animals that show complex responses have two hemispheres, Dr. Stieg said. A worm, for example, reacts to simple sensory input with a simple set of motor responses, he said. But the human brain deals with not just complex sensory input, but more diverse and complex motor responses mixed with an array of emotional and cognitive interplays. The result, he said, is that parts of the different hemispheres of the cerebral cortex, the top part of the brain, developed specialties. For just a few examples, he said, “the dominant side of the temporal lobes (the left in 97 percent of us) have speech and visual pathways; the parietal lobes, straight up from the ear, are intermixed on the dominant side, with the left handling speech; and the sensory function of one side of the body is handled by the other side, so that if the brain is bruised on the right side of the parietal lobe, and I hit you on the left side of the body, you might not pay attention to it.” Patients can have half their brain cut out to treat severe seizures and still function, but not at the same cognitive level, Dr. Stieg said. Copyright 2008 The New York Times Company

Related chapters from BP6e: Chapter 19: Language and Hemispheric Asymmetry
Related chapters from MM:Chapter 15: Language and Our Divided Brain
Link ID: 12180 - Posted: 06.24.2010

Nora Schultz Who ever heard of a fish being in two minds about something? Yet it seems that like humans, fish process information - and perhaps emotions - on different sides of the brain. Fish growing up in the wild among predators use their left eye to look at novel objects, while their offspring raised in captivity use the right eye. This suggests that life experiences can affect which side of the brain fish use, and even, says Victoria Braithwaite of the University of Edinburgh, UK, that they have emotional mindsets, since different sides of the brain may correspond to a curious or suspicious attitude. "The lab-reared fish could process information about novel objects in the left brain [which means they are looking at things with their right eye] because they feel more comfortable, whereas their parents are more cautious." “Lab-reared fish could process information about novel objects in the left brain because they feel more comfortable”Humans use their left and right brain lobes differently, the most well-known consequence being handedness. Brain lateralisation has been found in an increasing number of other species in recent years. "Especially for animals that have to cope with many predators, it is an advantage if they can use one hemisphere to keep an eye on predators while they use the other hemisphere to do other things," says Culum Brown, now at Macquarie University in Sydney, Australia. © Copyright Reed Business Information Ltd

Related chapters from BP6e: Chapter 19: Language and Hemispheric Asymmetry; Chapter 15: Emotions, Aggression, and Stress
Related chapters from MM:Chapter 15: Language and Our Divided Brain; Chapter 11: Emotions, Aggression, and Stress
Link ID: 10469 - Posted: 06.24.2010

by Nora Schultz HANDICRAFTS were never my strong point at school. For each project I attempted, I'd struggle with tools and techniques that didn't suit a left-hander like me, which often made me wonder why humans are wired to prefer using one side of the body over the other. Apart from a few wrist aches, though, my handedness hasn't been too much of a burden. Contrast this with the bad luck of a toad that fails to jump away from a snake approaching from its right, just because its right eye is much worse at spotting the danger than its left. Clearly, such asymmetry can have fatal consequences. All the more perplexing, then, that creatures across the animal kingdom - including mammals, birds, fish and invertebrates - prefer to use one paw, eye or even antenna for certain tasks, even though they may then be let down in crucial situations by their weaker side. The cause of this trait, called lateralisation, is fairly simple: one side of the brain, which generally controls the opposite side of the body, is more dominant than the other when processing certain tasks. Why would animal brains ever have evolved a characteristic that seems to put them in harm's way? Armed with a spate of ingenious cognitive tests, a group of animal psychologists think they've finally found the answer, in the shape of some previously overlooked benefits to a lopsided brain-body connection. Not before time. Up until the not-too-distant past, it had been broadly assumed that handedness was a uniquely human trait that evolved as a by-product of our amazing capacity for language. © Copyright Reed Business Information Ltd

Related chapters from BP6e: Chapter 19: Language and Hemispheric Asymmetry
Related chapters from MM:Chapter 15: Language and Our Divided Brain
Link ID: 14026 - Posted: 06.24.2010

by Linda Geddes IF HYPNOSIS leaves you unmoved, blame the wiring in your brain. It seems those who find it easier to fall into a trance are more likely to have an imbalance in the efficiency of their brain's two hemispheres. The finding backs hotly disputed claims of a biological basis for hypnosis. Around 15 per cent of people are thought to be extremely susceptibleMovie Camera to hypnosis, while another 10 per cent are almost impossible to hypnotise. The rest of us fall somewhere in between. Sceptics argue that rather than being in a genuine trance, some of us are simply more suggestible and therefore more likely to act the part. However, recent studies have hinted that during hypnosis, there is less connectivity between different regions, and less activity in the rational, left side of the brain, and more in the artistic right side. Such findings suggest hypnosis is more than acting. To see if there are also differences between the brains of susceptible and unresponsive volunteers when they were awake, Peter Naish of the Open University in Milton Keynes, UK, used a standard test of hypnotic susceptibility, that combines motor and cognitive tasks, to identify 10 volunteers of each type. He then gave each volunteer a pair of spectacles with an LED mounted on the left and right side of the frame. The two LEDs flashed in quick succession, and the volunteers had to say which flashed first. Naish repeated the task until the gap between the flashes was so short that the volunteers could no longer judge the correct order. © Copyright Reed Business Information Ltd.

Related chapters from BP6e: Chapter 19: Language and Hemispheric Asymmetry
Related chapters from MM:Chapter 15: Language and Our Divided Brain
Link ID: 13695 - Posted: 06.24.2010

Owen Flanagan, contributor I use the term "neuro-enthusiasta" for those given to excessive excitement over what brain science teaches. I have been warning, often in these pages, of its mostly amusing excesses and its tendency to produce newspaper headlines exclaiming that the brain "lights up" when people think and feel various things. Still, I did not foresee "neuro-" becoming a universal prefix. We have neuro-economics, neuro-theology, neuro-aesthetics and now, if Iain McGilchrist is to be believed, neuro-history. Plato, long before neuroscience, spoke of the struggle in the soul between Reason, Appetite and Temperament. This, neurologically speaking, has turned out to be the struggle between the brain's upper and lower regions. It's so last century. master_emissary_cover.jpgThe new story is the battle between the brain's hemispheres. "The left hemisphere is competitive, and its concern, its prime motivation is power," McGilchrist writes. The right, in contrast, is personal, empathetic and "primary", experiencing things in the lovey-dovey way we did in the old days when we sat around campfires singing Kumbaya. (Music, predictably, is so right brain). If the left hemisphere has its way, McGilchrist warns, the world will seem "relatively mechanical, an assemblage of more or less disconnected 'parts'... utilitarian in ethic; overconfident of its own take on reality, and lacking insight to its problems". © Copyright Reed Business Information Ltd.

Related chapters from BP6e: Chapter 19: Language and Hemispheric Asymmetry
Related chapters from MM:Chapter 15: Language and Our Divided Brain
Link ID: 13586 - Posted: 06.24.2010

By Michael Torrice For many animals, it pays to have a split mind. A brain with multiple lobes helps humans make more efficient decisions, and it allows birds to spot predators quickly. But a new study in fish uncovers possible hidden costs to a divided brain. Scientists once thought that only humans had a split in brain functions, called lateralization, with some tasks performed on the left side and others on the right. More recently, studies in primates, birds, and fish have suggested that asymmetric brains are common in many vertebrates and that more lateralized brains are more efficient. In a recent experiment, for example, parrots with more brain lateralization were more successful at finding seeds hidden among pebbles. But despite this cognitive boost, scientists have observed a great range of brain lateralization among fish and birds. Some of these animals can have almost completely symmetrical brains. So are there disadvantages to lateralization? To find out, Marco Dadda, a psychobiologist at the University of Padova in Italy, and his colleagues focused on goldbelly topminnows (Girardinus falcatus), a species known for its lateralized brain. For 4 years, the scientists bred three minnow groups to have different dominant sides of their brains. They determined the stronger half by watching which way the fish turned to avoid a predator: Turning right 80% of the time meant the right eye--and thus the left brain hemisphere--was dominant, whereas showing no turn preference pointed to a nonlateralized brain. © 2009 American Association for the Advancement of Science.

Related chapters from BP6e: Chapter 19: Language and Hemispheric Asymmetry
Related chapters from MM:Chapter 15: Language and Our Divided Brain
Link ID: 13317 - Posted: 06.24.2010

By Constance Holden The two sides of the brain are responsible for different tasks in many animals. In people, for example, the left side is usually the language center, whereas the right side handles more visual and spatial chores. Now, research on parrots shows that this separation increases brainpower. For many years, researchers thought that the division of labor in the brain, known as cerebral lateralization, was unique to humans. But recent research has shown that such lateralization is actually pervasive in vertebrates. A leading theory suggests that the attribute leads to faster, more accurate problem-solving. The theory holds true for minnows--the ones whose brains are lateralized are better at catching shrimp while simultaneously keeping an eye out for predators--but many other species haven't been tested. Among birds, parrots and crows are renowned for their cleverness. So behavioral ecologist Culum Brown and biologist Maria Magat of Macquarie University in Sydney, Australia, tested 40 parrots from eight different Australian species. Just as right-handedness indicates left-brain dominance in most humans, brain laterality was determined in birds by observing which eye each bird used to fixate on a piece of food and which foot grabbed it. Each bird received a laterality score ranging from 0 (no preference) to 5 (strongly lateralized). The parrots were then given two tests. One involved picking out seeds from a background of similar-looking pebbles; their performance was evaluated by dividing the number of seeds consumed by the number of pecks. The more challenging task required birds to obtain food hanging below their perch on a 50-centimeter-long string. Hauling up the prize is a problem requiring a lot of beak, foot, and eye coordination. © 2009 American Association for the Advancement of Science.

Related chapters from BP6e: Chapter 19: Language and Hemispheric Asymmetry
Related chapters from MM:Chapter 15: Language and Our Divided Brain
Link ID: 13235 - Posted: 06.24.2010