Chapter 19. Language and Hemispheric Asymmetry
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By Michelle Roberts Health editor, BBC News online Scientists say they have devised a helmet that can quickly determine whether a patient has had a stroke. It could speed diagnosis and treatment of stroke to boost chances of recovery, the scientists say. The wearable cap bounces microwaves off the brain to determine whether there has been a bleed or clot deep inside. The Swedish scientists who made the device plan to give it to ambulance crews to test after successful results in early studies with 45 patients. When a person has a stroke, doctors must work quickly to limit any brain damage. If it takes more than four hours to get to hospital and start treatment, parts of their brain tissue may already be dying. But to give the best treatment, doctors first need to find out if the stroke is caused by a leaky blood vessel or one blocked by a clot. A computerised tomography (CT) scan will show this, but it can take some time to organise one for a patient, even if they have been admitted as an emergency to a hospital that has one of these scanners. Any delay in this "golden hour" of treatment opportunity could hamper recovery. To speed up the process, researchers in Sweden, from Chalmers University of Technology, Sahlgrenska Academy and Sahlgrenska University Hospital, have come up with a mobile device that could be used on the way to hospital. The helmet uses microwave signals - the same as the ones emitted by microwave ovens and mobile phones but much weaker - to build a picture of what is going on throughout the brain. BBC © 2014
A selfie video that a 49-year-old Toronto-area woman took to show numbness and slurred speech she was experiencing helped doctors to diagnose her as having a mini-stroke, after she had earlier been given a diagnosis of stress. When Stacey Yepes’s face originally froze and she had trouble speaking in April, she remembered the signs of stroke from public service announcements. After the symptoms subsided, she went to a local emergency room, but the tests were clear and she was given tips on how to manage stress. The numbing sensation happened again as she left the hospital. When the left side of her body went numb while driving two days later, she pulled over, grabbed her smartphone and hit record. "The sensation is happening again," the Thornhill, Ont., woman says at the beginning of the video posted on YouTube by Toronto’s University Health Network. "It’s all tingling on left side," as she points to her lower lip, trying to smile. Yepes remembers that doctors said to breathe in and out and to try to manage stress, and she says she's trying. "I don’t know why this is happening to me." About a minute later, she shows that it’s hard to lift up her hand. "I think it was just to show somebody, because I knew it was not stress-related," she said in an interview. "And I thought if I could show somebody what was happening, they would have a better understanding." After going to Mount Sinai Hospital in downtown Toronto, Yepes was referred to Toronto Western Hospital’s stroke centre. © CBC 2014
Link ID: 19740 - Posted: 06.17.2014
As the popularity of soccer grows among children, doctors and researchers say the dangers of concussions need to be taken more seriously in the sport. When researchers at St. Michael's Hospital in Toronto reviewed the evidence on concussions and heading in soccer this winter, they found a higher incidence of concussions among females than males playing the world's most popular sport. Doctors warn that heading — purposely using the head to control and hit the ball — is a unique aspect of the beautiful game that needs more attention. Heading the ball isn’t necessarily going to cause an overt concussion with symptoms, but the accumulation of those impacts over time could cause difficulties with thinking, concentration and memory, said study author Monica Maher, a graduate student at the University of Toronto, and a former soccer goalkeeper. Maher doesn't want people to stop playing soccer or stop heading the ball. She does suggest limits on head exposure in younger children and padding on goal posts to prevent injury to the youngest players. Dr. David Robinson, a sports medicine physician at McMaster University in Hamilton, sees 10 to 15 concussions a week, including many related to soccer. "It's not a stretch to think that these chronic subconcussive blows may be softening the brain, injuring the brain over time," Robinson said. He calls it a step forward that balls are becoming lighter for young people. He reminds parents and coaches that if a concussion is suspected, it's best to remove an athlete from play. As for the differences in injury rates between males and females, Maher pointed to a few potential explanations: © CBC 2014
—By Indre Viskontas and Chris Mooney We've all been mesmerized by them—those beautiful brain scan images that make us feel like we're on the cutting edge of scientifically decoding how we think. But as soon as one neuroscience study purports to show which brain region lights up when we are enjoying Coca-Cola, or looking at cute puppies, or thinking we have souls, some other expert claims that "it's just a correlation," and you wonder whether researchers will ever get it right. Sam Kean But there's another approach to understanding how our minds work. In his new book, The Tale of the Dueling Neurosurgeons, Sam Kean tells the story of a handful of patients whose unique brains—rendered that way by surgical procedures, rare diseases, and unfortunate, freak accidents—taught us much more than any set of colorful scans. Kean recounts some of their unforgettable stories on the latest episode of the Inquiring Minds podcast. "As I was reading these [case studies] I said, 'That's baloney! There's no way that can possibly be true,'" Kean remembers, referring to one particularly surprising case in which a woman's brain injury left her unable to recognize and distinguish between different kinds of animals. "But then I looked into it, and I realized that, not only is it true, it actually reveals some important things about how the brain works." Here are five patients, from Kean's book, whose stories transformed neuroscience: 1. The man who could not imagine the future: Kent Cochrane (KC), pictured below, was a '70s wild child, playing in a rock band, getting into bar fights, and zooming around Toronto on his motorcycle. But in 1981, a motorcycle accident left him without two critical brain structures. Both of his hippocampi, the parts of the brain that allow us to form new long-term memories for facts and events in our lives, were lost. That's quite different from other amnesiacs, whose damage is either restricted to only one brain hemisphere, or includes large portions of regions outside of the hippocampus. Copyright ©2014 Mother Jones
by Bethany Brookshire Human vocal chords can produce an astonishing array of sounds: shrill and fearful, low and sultry, light and breathy, loud and firm. The slabs of muscle in our throat make the commanding sound of a powerful bass and a baby’s delightful, gurgling laugh. There are voices that must be taken seriously, voices that play and voices that seduce. And then there’s vocal fry. Bringing to mind celebrity voices like Kim Kardashian or Zooey Deschanel, vocal fry is a result of pushing the end of words and sentences into the lowest vocal register. When forcing the voice low, the vocal folds in the throat vibrate irregularly, allowing air to slip through. The result is a low, sizzling rattle underneath the tone. Recent studies have documented growing popularity of vocal fry among young women in the United States. But popular sizzle in women’s speech might be frying their job prospects, a new study reports. The findings suggest that people with this vocal affectation might want to hold the fry on the job market — and that people on the hiring side of the table might want to examine their biases. Vocal fry has been recognized since the 1970s, but now it’s thought of as a fad. Study coauthor Casey Klofstad, a political scientist at the University of Miami in Goral Gables, Fla., says that the media attention surrounding vocal fry generated a lot of speculation. “It is a good thing? Is it bad? It gave us a clear question we could test,” he says. Specifically, they wanted to study whether vocal fry had positive or negative effects on how people who used the technique were perceived. Led by Rindy Anderson from Duke University, the researchers recorded seven young men and seven young women speaking the phrase “Thank you for considering me for this opportunity.” Each person spoke the phrase twice, once with vocal fry and once without. Then the authors played the recordings to 800 participants ages 18 to 65, asking them to make judgments about the candidates based on voice alone. © Society for Science & the Public 2000 - 2013
Damage to certain parts of the brain can lead to a bizarre syndrome called hemispatial neglect, in which one loses awareness of one side of their body and the space around it. In extreme cases, a patient with hemispatial neglect might eat food from only one side of their plate, dress on only one side of their body, or shave or apply make-up to half of their face, apparently because they cannot pay attention to anything on that the other side. Research published last week now suggests that something like this happens to all of us when we drift off to sleep each night. The work could help researchers to understand the causes of hemispatial neglect, and why it affects one side far more often than the other. It also begins to reveal the profound changes in conscious experience that take place while we fall asleep, and the brain changes that accompany them. Hemispatial neglect is a debilitating condition that occurs often in people who suffer a stroke, where damage to the left hemisphere of the brain results in neglect of the right half of space, and vice versa. It can occur as a result of damage to certain parts of the frontal lobes, which are involved in alertness and attention, and the parietal lobes, which process information about the body and its surrounding space. In clinical tests, patients with hemispatial neglect are typically unaware of all kinds of stimuli in one half of space – they fail to acknowledge objects placed in the affected half of their visual field, for example and cannot state the location of touch sensations on the affected side of their body. Some may stop using the limbs on the affected side, or even deny that the limbs belong to them. Patients with neglect can usually see perfectly well, but information from the affected side just does not reach their conscious awareness. © 2014 Guardian News and Media Limited
Learning a second language can have a positive effect on the brain, even if it is taken up in adulthood, a University of Edinburgh study suggests. Researchers found that reading, verbal fluency and intelligence were improved in a study of 262 people tested either aged 11 or in their seventies. A previous study suggested that being bilingual could delay the onset of dementia by several years. The study is published in Annals of Neurology. The big question in this study was whether learning a new language improved cognitive functions or whether individuals with better cognitive abilities were more likely to become bilingual. Dr Thomas Bak, from the Centre for Cognitive Ageing and Cognitive Epidemiology at the University of Edinburgh, said he believed he had found the answer. Using data from intelligence tests on 262 Edinburgh-born individuals at the age of 11, the study looked at how their cognitive abilities had changed when they were tested again in their seventies. The research was conducted between 2008 and 2010. All participants said they were able to communicate in at least one language other than English. Of that group, 195 learned the second language before the age of 18, and 65 learned it after that time. The findings indicate that those who spoke two or more languages had significantly better cognitive abilities compared to what would have been expected from their baseline test. The strongest effects were seen in general intelligence and reading. The effects were present in those who learned their second language early, as well as later in life. BBC © 2014
By GRETCHEN REYNOLDS A new study found subtle differences in the brains of college football players when compared to other students.Tim Larsen for The New York TimesA new study found subtle differences in the brains of college football players when compared to other students. The brains of college football players are subtly different from the brains of other students, especially if the players have experienced a concussion in the past, according to an important new brain-scan study that, while restrained in its conclusions, adds to concerns that sports-related hits to the head could have lingering effects on the brain, even among the young and healthy. Almost all of us have heard by now that concussions are more injurious than was once believed. It’s been widely reported that the autopsied brains of some professional football and hockey players who experienced repeated hits to the head showed signs of severe and progressive brain damage. Meanwhile, recent studies with living animals suggest that the brain may respond to even mild concussive blows with inflammatory and other reactions that, while designed to spur healing, could also contribute to tissue damage. But many fundamental questions about the long-term impacts of blows to the head during sports remain unanswered, including which portions of the brain are most affected, whether any brain changes also affect the ability to think, and if playing a contact sport might alter the structure and function of the brains of athletes, even ones who have never experienced a confirmed concussion. So, for a study published last week in JAMA, researchers at the Laureate Institute for Brain Research and the University of Tulsa, both in Tulsa, Okla., and other institutions, started delving into those issues by turning to the university’s Division I football team. Tulsa is, of course, in the heart of football country. But the researchers say they met no resistance from the school, team or players. © 2014 The New York Times Company
Keyword: Brain Injury/Concussion
Link ID: 19644 - Posted: 05.21.2014
By NATASHA SINGER Joseph J. Atick cased the floor of the Ronald Reagan Building and International Trade Center in Washington as if he owned the place. In a way, he did. He was one of the organizers of the event, a conference and trade show for the biometrics security industry. Perhaps more to the point, a number of the wares on display, like an airport face-scanning checkpoint, could trace their lineage to his work. A physicist, Dr. Atick is one of the pioneer entrepreneurs of modern face recognition. Having helped advance the fundamental face-matching technology in the 1990s, he went into business and promoted the systems to government agencies looking to identify criminals or prevent identity fraud. “We saved lives,” he said during the conference in mid-March. “We have solved crimes.” Thanks in part to his boosterism, the global business of biometrics — using people’s unique physiological characteristics, like their fingerprint ridges and facial features, to learn or confirm their identity — is booming. It generated an estimated $7.2 billion in 2012, according to reports by Frost & Sullivan. Making his rounds at the trade show, Dr. Atick, a short, trim man with an indeterminate Mediterranean accent, warmly greeted industry representatives at their exhibition booths. Once he was safely out of earshot, however, he worried aloud about what he was seeing. What were those companies’ policies for retaining and reusing consumers’ facial data? Could they identify individuals without their explicit consent? Were they running face-matching queries for government agencies on the side? Now an industry consultant, Dr. Atick finds himself in a delicate position. While promoting and profiting from an industry that he helped foster, he also feels compelled to caution against its unfettered proliferation. He isn’t so much concerned about government agencies that use face recognition openly for specific purposes — for example, the many state motor vehicle departments that scan drivers’ faces as a way to prevent license duplications and fraud. Rather, what troubles him is the potential exploitation of face recognition to identify ordinary and unwitting citizens as they go about their lives in public. Online, we are all tracked. But to Dr. Atick, the street remains a haven, and he frets that he may have abetted a technology that could upend the social order. © 2014 The New York Times Company
Link ID: 19630 - Posted: 05.18.2014
|By Sam Kean It is possible to take the idea of left/right differences within the brain too far: it’s not like one side of the brain talks or emotes or recognizes faces all by itself while the other one just sits there twiddling its neurons. But the left and right hemispheres of the human brain do show striking differences in some areas, especially with regard to language, the trait that best defines us as human beings. Scientists suspect that left-right specialization first evolved many millions of years ago, since many other animals show subtle hemispheric differences: they prefer to use one claw or paw to eat, for instance, or they strike at prey more often in one direction than another. Before this time, the left brain and right brain probably monitored sensory data and recorded details about the world to an equal degree. But there’s no good reason for both hemispheres to do the same basic job, not if the corpus callosum—a huge bundle of fibers that connects the left and right brain—can transmit data between them. So the brain eliminated the redundancy, and the left brain took on new tasks. This process accelerated in human beings, and we humans show far greater left/right differences than any other animal. In the course of its evolution the left brain also took on the crucial role of master interpreter. Neuroscientists have long debated whether certain people have two independent minds running in parallel inside their skulls. That sounds spooky, but some evidence suggests yes. For example, there are split-brain patients, who had their corpus callosums surgically severed to help control epilepsy and whose left and right brain cannot communicate as a result. Split-brain patients have little trouble drawing two different geometric figures at the same time, one with each hand. Normal people bomb this test. (Try it, and you’ll see how mind-bendingly hard it is.) Some neuroscientists scoff at these anecdotes, saying the claims for two separate minds are exaggerated. But one thing is certain: two minds or no, split-brain people feel mentally unified; they never feel the two hemispheres fighting for control, or feel their consciousness flipping back and forth. That’s because one hemisphere, usually the left, takes charge. And many neuroscientists argue that the same thing happens in normal brains. One hemisphere probably always dominates the mind, a role that neuroscientist Michael Gazzaniga called the interpreter. (Per George W. Bush, you could also call it “the decider.”) © 2014 Scientific American
Link ID: 19625 - Posted: 05.16.2014
by Nathan Collins There's a new twist in mental health. People with depression seem three times as likely as those without it to have two brain lobes curled around each other. The brains of people with depression can be physically different from other brains – they are often smaller, for example – but exactly why that is so remains unclear. In humans, some studies point to changes in the size of the hippocampi, structures near the back of the brain thought to support memory formation. "There are so many studies that show a smaller hippocampus in almost every psychiatric disorder," says Jerome Maller, a neuroscientist at the Monash Alfred Psychiatry Research Centre in Melbourne, Australia, who led the latest work looking at brain lobes. "But very few can actually show or hypothesize why that is." Maller thinks he has stumbled on an explanation. He had been using a brain stimulation technique known as transcranial magnetic stimulation as a therapy for antidepressant-resistant depression. This involved using fMRI scans to create detailed maps of the brain to determine which parts to stimulate. While pouring over hundreds of those maps, Maller noticed that many of them showed signs of occipital bending. This is where occipital lobes – which are important for vision – at the back of the brain's left and right hemispheres twist around each other. So he and his colleagues scanned 51 people with and 48 without major depressive disorder. They found that about 35 per cent of those with depression and 12.5 per cent of the others showed signs of occipital bending. The difference was even greater in women: 46 per cent of women with depression had occipital bending compared with just 6 per cent of those without depression. © Copyright Reed Business Information Ltd.
by Anil Ananthaswamy Children born with split brains – whereby the two hemispheres of their brains are not connected – can develop new brain wiring that helps to connect the two halves, according to brain scans of people with the condition. Such circuitry is not present in normal brains, and explains how some people with split brains can still maintain normal function. It also suggests that the developing brain is even more adaptable than previously thought. Research into people with split brains goes back to the 1960s, when neuroscientists studied people who had undergone brain surgery to treat particularly severe epilepsy. The surgery involved cutting the corpus callosum, the thick bundle of neuronal fibres that connects the brain's two halves. This disconnection prevented epileptic seizures spreading from one brain hemisphere to the other. The recipients of such split-brain surgery showed a form of disconnection syndrome whereby the two halves of their brains could not exchange information. For instance, if a patient touched an object with their left hand without seeing the object, they would be unable to name it. That is because sensory-motor signals from the left hand are processed in the right hemisphere. To put a name to the object, the tactile information from the hand has to reach the brain's left hemisphere, the seat of language. With the central connection between hemispheres severed, the object's naming information cannot be retrieved. Conversely, if that person were to touch an object with their right hand without seeing it, the sensory-motor signals from that hand would go to the left hemisphere, which hosts the brain's language centres, making naming the object easy. However, children born without a corpus callosum – and therefore whose two brain hemispheres are separated – can often pass such tactile naming tests when they are old enough to take them. Their brain hemispheres are obviously communicating, but it wasn't clear how. © Copyright Reed Business Information Ltd
By Eric Niiler, Scientists studying head injuries have found something surprising: Genes may make some people more susceptible to concussion and trauma than others. A person’s genetic makeup, in fact, may play a more important role in the extent of injury than the number of blows a person sustains. While this research is still in its infancy, these scientists are working toward developing a blood test that may one day help a person decide — based on his her or her genetic predisposition — whether to try out for the football team, or perhaps take up swimming or chess instead. “Until now, all the attention has been paid to how hard and how often you get hit,” said Thomas McAllister, a professor of clinical psychiatry at the Indiana University School of Medicine. “No doubt that’s important. But it’s also becoming clear that’s it’s probably an interaction between the injury and the genetics of the person being injured.” This research is being spurred by fears that some athletes and many returning soldiers may face a lifetime of problems from head injuries. The National Football League agreed to settle a class-action concussion lawsuit by retired players last August for $765 million, although a judge rejected the agreement. In addition, the Pentagon estimates that 294,000 troops, many of whom served in Iraq and Afghanistan, suffered some kind of brain injury since 2000. “More and more we are noticing our servicemen are coming home with significant problems with brain function,” said Daniel Perl, a neuropathologist at the Center for Neuroscience and Regenerative Medicine at the Pentagon’s Uniformed Services University for Health Sciences in Bethesda. “We don’t know much about the biology of this. We need to get down to cellular level of resolution, how the brain starts to repair itself.” © 1996-2014 The Washington Post
By SAM KEAN UNTIL the past few decades, neuroscientists really had only one way to study the human brain: Wait for strokes or some other disaster to strike people, and if the victims pulled through, determine how their minds worked differently afterward. Depending on what part of the brain suffered, strange things might happen. Parents couldn’t recognize their children. Normal people became pathological liars. Some people lost the ability to speak — but could sing just fine. These incidents have become classic case studies, fodder for innumerable textbooks and bull sessions around the lab. The names of these patients — H. M., Tan, Phineas Gage — are deeply woven into the lore of neuroscience. When recounting these cases today, neuroscientists naturally focus on these patients’ deficits, emphasizing the changes that took place in their thinking and behavior. After all, there’s no better way to learn what some structure in the brain does than to see what happens when it shorts out or otherwise gets destroyed. But these case snippets overlook something crucial about people with brain damage. However glaring their deficits are, their brains still work like ours to a large extent. Most can still read and reason. They can still talk, walk and emote. And they still have the same joys and fears — facts that the psychological caricatures passed down from generation to generation generally omit. The famous amnesiac H. M., for instance, underwent radical brain surgery in 1953 and had most of the hippocampus removed on both sides of his brain; afterward, he seemed to lose the ability to form new long-term memories. Names, dates, directions to the bathroom all escaped him now. He’d eat two breakfasts if no one stopped him. Careful testing, however, revealed that H. M. could form new motor memories — memories of things like how to ride a bicycle — because they rely on different structures in the brain. This work established that memory isn’t a single, monolithic thing, but a collection of different faculties. © 2014 The New York Times Company
By Deborah Tuerkheimer Almost a decade into a 20-year prison sentence for murdering a baby in her care, 43-year-old Jennifer Del Prete was ordered freed on bond late last week. The ruling is one of a growing number that reflect skepticism on the part of judges, juries, and even prosecutors about criminal convictions based on the medical diagnosis of shaken baby syndrome. The case is also a critical turning point. The certainty that once surrounded shaken baby syndrome, or SBS, has been dissolving for years. The justice system is beginning to acknowledge this shift but should go further to re-examine and perhaps overturn more past convictions. Doctors once believed that three neurological symptoms—bleeding beneath the outer layer of membranes surrounding the brain (subdural hemorrhaging), bleeding in the retina, and brain swelling—always meant that a baby had been shaken. Because it was accepted that a baby with these three symptoms would show the effect of brain damage immediately, the “triad,” as it became known, was also used to establish the identity of the abuser—the last person with the baby. SBS was, in essence, a medical diagnosis of murder. Beginning in the 1990s, hundreds of cases were prosecuted based on this conception of SBS. The evidence of guilt was strikingly similar from case to case. This includes the Illinois prosecution of Jennifer Del Prete. In 2002, Del Prete was working at a small home day care in a Chicago suburb. One day, when she went to feed the 4-month-old baby in her care, she says she discovered the infant limp. Because the baby had the telltale triad of SBS symptoms, doctors were sure that Del Prete had shaken the baby to death. She denied it, and there were no witnesses. But based on the testimony of medical experts—primarily a pediatrician—she was convicted of murder in the first degree. © 2014 The Slate Group LLC.
by Colin Barras Enough of the cheap jibes: Neanderthals may have been just as clever as modern humans. Anthropologists have already demolished the idea that Neanderthals were dumb brutes, and now a review of the archaeological record suggests they were our equals. Neanderthals were one of the most successful of all hominin species, occupying much of Europe and Asia. Their final demise about 40,000 years ago, shortly after Homo sapiens walked into their territory, is often put down to the superiority of our species. It's time to lay that idea to rest, say Paola Villa at the University of Colorado in Boulder and Wil Roebroeks at Leiden University in the Netherlands. Just as smart as you For instance, there is evidence that Homo sapiens could use fire to chemically transform natural materials into glue 70,000 years ago, but Neanderthals were performing similarly complex chemical syntheses at least 200,000 years ago. And although 70,000-year-old engraved ochre from South Africa is seen as evidence that our species had developed sophisticated symbolism and perhaps even language, similar artefacts have been found at 50,000-year-old Neanderthal sites in Spain. What's more, Neanderthals might have been able to talk. Late last year we learned that our extinct cousins had a hyoid, a small bone in the neck that plays a big role in speech, very like ours. Evidence has even emerged that Homo sapiens may have learned some skills by copying Neanderthals. Yet despite all of this evidence, the idea that Neanderthals were our inferiors still persists. © Copyright Reed Business Information Ltd.
By Gabriella Rosen Kellerman By 1664, the year he published his most famous book of neuroanatomy, Cerebri Anatome, Dr. Thomas Willis was already renowned in Britain for saving lives. Fourteen years earlier, the corpse of executed murderer Anne Green had been delivered to Willis and some of his colleagues for autopsy. Upon opening the coffin—the story goes—the doctors heard a gasp. Ms. Green, they discovered, had been hanged but not executed. Thanks to the resuscitation efforts of Willis and his colleagues, Green survived, and was given a stay of execution. She died fifteen years later. The episode supposedly drew jealousy from Willis’s contemporaries, who could have had no idea just how many lives Willis’s work would one day save. Among the important discoveries included in Cerebri Anatome, considered the founding text of neurology, is the Circle of Willis, a map of the interconnecting arteries at the base of the brain. Such circular connections among arteries are called anastomoses. They enable blood to reach vital tissue along multiple routes so that when one is blocked, the blood has an alternative outlet. The Circle of Willis is perhaps most important because of its implications for stroke. Stroke, which is the third leading cause of death in this country, occurs when blood flow to the brain is disrupted. This can occur when an artery gets blocked with plaque or a clot (called an ischemic stroke) or when at artery bursts (called hemorrhagic stroke). Many of these problems, particularly the latter kind of stroke, occur in the Circle of Willis. © 2014 Scientific American
Link ID: 19564 - Posted: 05.03.2014
Fork-tailed drongos, glossy black African songbirds with ruby-colored eyes, are the avian kingdom’s masters of deception. They mimic the alarm calls of other species to scare animals away and then swipe their dupes’ dinner. But like the boy who cried wolf, drongos can raise the alarm once too often. Now, scientists have discovered that when one false alarm no longer works, the birds switch to another species’ warning cry, a tactic that usually does the trick. “The findings are astounding,” says John Marzluff, a wildlife biologist at the University of Washington, Seattle, who was not involved in the work. “Drongos are exceedingly deceptive; their vocabularies are immense; and they match their deception to both the target animal and [its] past response. This level of sophistication is incredible.” Since 2008, Tom Flower, an evolutionary biologist at the University of Cape Town, has followed drongos in the Kuruman River Reserve in the Kalahari Desert. He’s habituated and banded about 200 of the robin-sized birds, and, using food rewards, has trained individuals to come to him when he calls. After getting its snack, the drongo quickly returns to its natural behavior—catching insects and following other bird species or meerkats—while Flower tags along. Drongos also keep an eye out for raptors and other predators. When they spot one, they utter metallic alarm cries. Meerkats and pied babblers, a highly social bird, pay attention to the drongos and dash for cover when the drongos raise an alarm—just as they do when one of their own calls out a warning. Studies have shown that having drongos around benefits animals of other species, which don’t have to be as vigilant and can spend more time foraging. But there’s a trade-off: The drongos’ cries aren’t always honest. When a meerkat has caught a fat grub or gecko, a drongo is apt to change from trustworthy sentinel to wily deceiver. © 2014 American Association for the Advancement of Science.
Brian Owens If you think you know what you just said, think again. People can be tricked into believing they have just said something they did not, researchers report this week. The dominant model of how speech works is that it is planned in advance — speakers begin with a conscious idea of exactly what they are going to say. But some researchers think that speech is not entirely planned, and that people know what they are saying in part through hearing themselves speak. So cognitive scientist Andreas Lind and his colleagues at Lund University in Sweden wanted to see what would happen if someone said one word, but heard themselves saying another. “If we use auditory feedback to compare what we say with a well-specified intention, then any mismatch should be quickly detected,” he says. “But if the feedback is instead a powerful factor in a dynamic, interpretative process, then the manipulation could go undetected.” In Lind’s experiment, participants took a Stroop test — in which a person is shown, for example, the word ‘red’ printed in blue and is asked to name the colour of the type (in this case, blue). During the test, participants heard their responses through headphones. The responses were recorded so that Lind could occasionally play back the wrong word, giving participants auditory feedback of their own voice saying something different from what they had just said. Lind chose the words ‘grey’ and ‘green’ (grå and grön in Swedish) to switch, as they sound similar but have different meanings. © 2014 Nature Publishing Group
Does reading faster mean reading better? That’s what speed-reading apps claim, promising to boost not just the number of words you read per minute, but also how well you understand a text. There’s just one problem: The same thing that speeds up reading actually gets in the way of comprehension, according to a new study. When you read at your natural pace, your eyes move back and forth across a sentence, rather than plowing straight through to the end. Apps like Spritz or the aptly named Speed Read are built around the idea that these eye movements, called saccades, are a redundant waste of time. It’s more efficient, their designers claim, to present words one at a time in a fixed spot on a screen, discouraging saccades and helping you get through a text more quickly. This method, called rapid serial visual presentation (RSVP), has been controversial since the 1980s, when tests showed it impaired comprehension, though researchers weren’t quite sure why. With a new crop of speed-reading products on the market, psychologists decided to dig a bit more and uncovered a simple explanation for RSVP’s flaw: Every so often, we need to scan backward and reread for a better grasp of the material. Researchers demonstrated that need by presenting 40 college students with ambiguous, unpunctuated sentences ("While the man drank the water that was clear and cold overflowed from the toilet”) while following their subjects’ gaze with an eye-tracking camera. Half the time, the team crossed out words participants had already read, preventing them from rereading (“xxxxx xxx xxx drank the water …”). Following up with basic yes-no questions about each sentence’s content, they found that comprehension dropped by about 25% in trials that blocked rereading versus those that didn’t, the researchers report online this month in Psychological Science. Crucially, the drop was about the same when subjects could, but simply hadn’t, reread parts of a sentence. Nor did the results differ much when using ambiguous sentences or their less confusing counterparts (“While the man slept the water …”). Turns out rereading isn’t a waste of time—it’s essential for understanding. © 2014 American Association for the Advancement of Science.