Chapter 14. Attention and Consciousness
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|By Nathan Collins A car detects when a driver starts to nod off and gently pulls over. A tablet or laptop senses its user is confused and offers assistance. Such interventions seem futuristic, but in fact they may not require any technological breakthroughs: a recent study suggests that with the aid of a standard camera, a simple computer program can learn to read people's eye movements to determine what they are doing and perhaps how they are feeling. Psychologists at the University of South Carolina were curious if a computer could figure out what a person was up to based on their eye movements. They first had 12 people engage in four tasks, including reading lines of text and searching photographs for a specific printed letter. Each person repeated the tasks 35 to 50 times while a camera recorded how their eyes moved. Using a subset of those data, the team trained a simple computer program, called a naive Bayes classifier, to identify which of the four tasks each person was doing. In the remaining trials, the classifier correctly determined which task the person was working on 75 percent of the time, well above the 25 percent expected by chance. Because the computer program is based on a flexible algorithm that is simple but powerful, this set-up could most likely be used to identify emotions or mental states such as confusion or fatigue, the researchers suggest in the paper, which appeared in September 2013 in PLOS ONE. With only a brief training period, a car's onboard computer—existing models are more than powerful enough—could learn how a driver's gaze changed as he or she became more exhausted. Further work, the authors suggest, could lead to devices capable of identifying and aiding people in need of assistance in a variety of situations. © 2014 Scientific American
By Neuroskeptic A neuroscience paper published before Christmas drew my eye with the expansive title: “How Thoughts Give Rise to Action“ Subtitled “Conscious Motor Intention Increases the Excitability of Target-Specific Motor Circuits”, the article’s abstract was no less bold, concluding that: These results indicate that conscious intentions govern motor function… until today, it was unclear whether conscious motor intention exists prior to movement, or whether the brain constructs such an intention after movement initiation. The authors, Zschorlich and Köhling of the University of Rostock, Germany, are weighing into a long-standing debate in philosophy, psychology, and neuroscience, concerning the role of consciousness in controlling our actions. To simplify, one school of thought holds that (at least some of the time), our intentions or plans control our actions. Many people would say that this is what common sense teaches us as well. But there’s an alternative view, in which our consciously-experienced intentions are not causes of our actions but are actually products of them, being generated after the action has already begun. This view is certainly counterintuitive, and many find it disturbing as it seems to undermine ‘free will’. That’s the background. Zschorlich and Köhling say that they’ve demonstrated that conscious intentions do exist, prior to motor actions, and that these intentions are accompanied by particular changes in brain activity. They claim to have done this using transcranial magnetic stimulation (TMS), a way of causing a localized modulation of brain electrical activity.
Link ID: 19370 - Posted: 03.17.2014
Linda Carroll TODAY contributor The stimulants used to treat ADHD might be making kids fat, a new study suggests. A study of more than 160,000 youngsters found that kids with Attention Deficit and Hyperactivity Disorder who received stimulants were at increased risk of becoming obese as they hit their teens. In contrast, kids with ADHD who took non-stimulant medications or got no therapy were very comparable, in terms of weight gain, to kids who didn’t have the disorder. “Our data suggest that stimulant use during childhood might have lifelong effects,” said Dr. Brian Schwartz, the study’s lead author and a professor of environmental health sciences, epidemiology, and medicine at the Johns Hopkins Bloomberg School of Public Health and senior investigator at the Geisinger Center for Health Research. “They might reset all sorts of physical properties and appetite parameters.” The new research may have uncovered a growing public health issue, Schwartz said. “Our data would seem to offer a lot of cause for concern with respect to prescribing stimulants,” he explained. Schwartz and his colleagues started the study because they were perplexed by the apparent paradox of hyperactive kids being prone to obesity. They scrutinized 12 years-worth of medical information from 163,820 Pennsylvania children, 13,427 of whom received an ADHD diagnosis.
Think women can’t do math? You’re wrong—but new research shows you might not change your mind, even if you get evidence to the contrary. A study of how both men and women perceive each other's mathematical ability finds that an unconscious bias against women could be skewing hiring decisions, widening the gender gap in mathematical professions like engineering. The inspiration for the experiment was a 2008 study published in Science that analyzed the results of a standardized test of math and verbal abilities taken by 15-year-olds around the world. The results challenged the pernicious stereotype that females are biologically inferior at mathematics. Although the female test-takers lagged behind males on the math portion of the test, the size of the gap closely tracked the degree of gender inequality in their countries, shrinking to nearly zero in emancipated countries like Sweden and Norway. That suggests that cultural biases rather than biology may be the better explanation for the math gender gap. To tease out the mechanism of discrimination, two of the authors of the 2008 study, Paola Sapienza and Luigi Zingales, economic researchers at Northwestern University’s Kellogg School of Management in Evanston, Illinois, and the University of Chicago Booth School of Business in Illinois, respectively, teamed up with Ernesto Reuben, an experimental psychologist at Columbia Business School in New York City, to design an experiment to test people's gender bias when it comes to judging mathematical ability. Study participants of both genders were divided into two groups: employers and job candidates. The job was simple: As accurately and quickly as possible, add up sets of two-digit numbers in a 4-minute math sprint. (The researchers did not tell the subjects, but it is already known that men and women perform equally well on this task.) © 2014 American Association for the Advancement of Science.
Think you’ll always pick chocolate over a bag of chips? Don’t be so sure. Researchers have found that if they can get people to pay more attention to a particular type of junk food, they will begin to prefer it—even weeks or months after the experiment. The finding suggests a new way to manipulate our decisions and perhaps even encourage us to pick healthy foods. “This paper is provocative and very well done,” says Antonio Rangel, a neuroeconomist at the California Institute of Technology in Pasadena, who was not involved in the new study. “It is exciting because it’s a proof of concept that a relatively simple intervention can have this long-lasting effect.” Economists who study decision-making had previously found that, when deciding between multiple items, people tend to let their gaze linger on the things that they end up choosing. This observation has motivated companies to pursue flashy packaging to attract consumers’ eyes. Tom Schonberg, a neuroscientist at the University of Texas, Austin, wondered whether people’s preferences could be changed before being faced with such a decision by training their brains to pay more attention to certain items. His first task was figuring out what kind of junk food people preferred. He and his colleagues recruited more than 200 university students and set up an auction-style program that asked them how much they were willing to pay for 60 different kinds of snacks, from M&M’s to Fritos. Then, the participants went through a 30- to 50-minute computer training program that showed photos of foods that the participants had already rated. When some treats appeared on the screen, a short tone would play and signal the subject to press a button as fast as possible. When other treats popped up, the computer remained silent and the subject refrained from pressing the button. © 2014 American Association for the Advancement of Science
|By Jason G. Goldman Most people don't spend much time pondering the diameter of their pupils. The fact is that we don't have much control over our pupils, the openings in the center of the irises that allow light into the eyes. Short of chemical interventions—such as the eyedrops ophthalmologists use to widen their patients' pupils for eye exams—the only way to dilate or shrink the pupils is by changing the amount of available light. Switch off the lamp, and your pupils will widen to take in more light. Step out into the sun, and your pupils will narrow. Mechanical though they may be, the workings of pupils are allowing researchers to explore the parallels between imagination and perception. In a recent series of experiments, University of Oslo cognitive neuroscientists Bruno Laeng and Unni Sulutvedt began by displaying triangles of varying brightness on a computer screen while monitoring the pupils of the study volunteers. The subjects' pupils widened for dark shapes and narrowed for bright ones, as expected. Next, participants were instructed to simply imagine the same triangles. Remarkably, their pupils constricted or dilated as if they had been staring at the actual shapes. Laeng and Sulutvedt saw the same pattern when they asked subjects to imagine more complex scenes, such as a sunny sky or a dark room. Imagination is usually thought of as “a private and subjective experience, which is not accompanied by strongly felt or visible physiological changes,” Laeng says. But the new findings, published in Psychological Science, challenge that idea. The study suggests that imagination and perception may rely on a similar set of neural processes: when you picture a dimly lit restaurant, your brain and body respond, at least to some degree, as if you were in that restaurant. © 2014 Scientific American
by Tom Siegfried Max Planck, who shook the world with his discovery of quantum physics, also offered a warning. “One must be careful,” he said, “when using the word, real.” It was good advice. As physicists explored the quantum domain, they found that usual ideas about reality did not apply. Reality in the realm of atoms was nothing like the world of rocks and baseballs and planets, where Newton’s laws of motions ruled with rigor. Among atoms, the rules were more like Olympic ice skating judging, with unpredictable scores. Gradually physicists, engineers and even screenwriters became familiar with quantum weirdness and used it in lasers, computers and movie plots. Quantum reality might be crazy, but it’s our reality, and most scientists, anyway, have become more or less used to it. Nevertheless, Planck’s warning still applies. Perhaps the quantum picture of reality is another illusion, just like Newton’s was. Human insight into nature may not yet have penetrated reality’s ultimate veil. In other words, maybe reality always dresses itself up in Newtonian or Einsteinian or quantum clothing, and science hasn’t yet seen what reality looks like naked. And that might explain why nature has been able to protect so many of its mysteries from science’s prying eyes — mysteries like the identity of dark matter, the math describing quantum gravity, the mechanism underlying consciousness. And whether humans have free will. Maybe reality always dresses itself up in Newtonian or Einsteinian or quantum clothing, and science hasn’t yet seen what reality looks like naked. © Society for Science & the Public 2000 - 2013.
Link ID: 19319 - Posted: 03.04.2014
By STEPHEN P. HINSHAW and RICHARD M. SCHEFFLER BERKELEY, Calif. — THE writing is on the chalkboard. Over the next few years, America can count on a major expansion of early childhood education. We embrace this trend, but as health policy researchers, we want to raise a major caveat: Unless we’re careful, today’s preschool bandwagon could lead straight to an epidemic of 4- and 5-year-olds wrongfully being told that they have attention deficit hyperactivity disorder. Introducing millions of 3- to 5-year-olds to classrooms and preacademic demands means that many more distracted kids will undoubtedly catch the attention of their teachers. Sure, many children this age are already in preschool, but making the movement universal and embedding transitional-K programs in public schools is bound to increase the pressure. We’re all for high standards, but danger lurks. The American Academy of Pediatrics now endorses the idea that the diagnosis of A.D.H.D. can and should begin at age 4, before problems accumulate. In fact, Adderall and other stimulants are approved for treatment of attentional issues in children as young as 3. Early intervention for children with A.D.H.D. could provide great relief. Children who go untreated have major difficulties in school and with their peers, and they have higher-than-normal rates of accidents and physical injuries. The problem is that millions of American children have been labeled with A.D.H.D. when they don’t truly have it. Our research has revealed a worrisome parallel between our nation’s increasing push for academic achievement and increased school accountability — and skyrocketing A.D.H.D. diagnoses, particularly for the nation’s poorest children. © 2014 The New York Times Company
by Helen Thomson People in a vegetative state showed signs of awareness after electric brain stimulation – and minimally conscious people were able to communicate again TALK about an awakening. People who have been in a minimally conscious state for weeks or years have been temporarily roused using mild electrical stimulation. Soon after it was applied to their brains, 15 people with severe brain damage showed signs of consciousness, including moving their hands or following instructions using their eyes. Two people were even able to answer questions for 2 hours before drifting back into their previous uncommunicative state. "I don't want to give people false hope – these people weren't getting up and walking around – but it shows there is potential for the brain to recover functionality, even several years after damage," says Steven Laureys at the University of Liège in Belgium, who led the research. People with severe brain trauma often fall into a coma. If they "awaken", by showing signs of arousal but not awareness, they are said to be in a vegetative state. This can improve to a state of minimal consciousness, where they might show fluctuating signs of awareness, which come and go, but have no ability to communicate. External stimulation of the brain has been shown to increase arousal, awareness and aspects of cognition in healthy people. So Laureys and his colleagues wondered if it would do the same in people with severe brain damage. They used transcranial direct current stimulation (tDCS), which doesn't directly excite the brain, but uses low-level electrical stimulation to make neurons more or less likely to fire. © Copyright Reed Business Information Ltd.
Link ID: 19301 - Posted: 02.27.2014
by Tom Siegfried If freedom is just another word for nothing left to lose, then “free will” is just another phrase for ability to choose. Bad, wasn’t it? But if free will is an illusion, as many scientists and philosophers have argued, then you shouldn’t blame me. On the other hand, I do blame myself. Because like most bloggers, and possibly even the several dozen humans who don’t blog, I think I decided for myself what to write. Besides, as many investigators of this issue have pointed out, it’s not so obvious that free will is illusory now that quantum mechanics has inserted some randomness into nature. Sadly, though, that reasoning doesn’t get you very far. There’s randomness in the quantum world, all right, just like the unpredictable sequence of winning numbers on a roulette wheel. But in the long run all the numbers turn up about equally often. Free will isn’t worth much if you can’t use it to beat a casino. And as MIT physicist Scott Aaronson points out, quantum math is similar: It gives the odds about what various possible things will happen, and those odds are always predicted precisely. The probability distribution of results is always just what the quantum math says it will be. Aaronson doesn’t see any free will there. Still, the free will question has elicited some sophisticated musing from quantum physicists who like to contemplate the interface of mentality and physical reality. It seems reasonable enough to reexamine such an old question in the light of the latest understanding of the universe. It may be that modern physics can offer a perspective giving hope for those who like to make up their own mind. © Society for Science & the Public 2000 - 2013.
Link ID: 19299 - Posted: 02.27.2014
Sara Reardon Two monkeys sit at computer screens, eyeing one another as they wait for a promised reward: apple juice. Each has a choice — it can either select a symbol that results in juice being shared equally, or pick one that delivers most of the juice to itself. But being selfish is risky. If its partner also chooses not to share, neither gets much juice. This game, the ‘prisoner’s dilemma’, is a classic test of strategy that involves the simultaneous evaluation of an opponent’s thinking. Researchers have now discovered — and manipulated — specific brain circuits in rhesus macaques (Macaca mulatta) that seem to be involved in the animals’ choices, and in their assessments of their partners’ choices. Investigating the connections could shed light on how social context affects decision-making in humans, and how disorders that affect social skills, such as autism spectrum disorder, disrupt brain circuitry. “Once we have identified that there are particular neural signals necessary to drive the processes, we can begin to tinker,” says Michael Platt, a neurobiologist at Duke University in Durham, North Carolina. Neurobiologists Keren Haroush and Ziv Williams of Harvard Medical School in Boston, Massachusetts, zoomed in on neural circuits in rhesus macaques by implanting electrode arrays into a brain area called the dorsal anterior cingulate cortex (dACC), which is associated with rewards and decision-making. The arrays recorded the activity of hundreds of individual neurons. When the monkeys played the prisoner’s dilemma (see ‘A juicy experiment’) against a computer program, they rarely chose to cooperate. But when they played with another monkey that they could see, they were several times more likely to choose to share the juice. © 2014 Nature Publishing Group
|By Lila Stanners Beauty seems mysterious and subjective. Scientists have long attempted to explain why the same object can strike some individuals as breathtaking and others as repulsive. Now a study finds that applying stimulation to a certain brain area enhances people's aesthetic appreciation of visual images. First, participants viewed 70 abstract paintings and sketches and 80 representational (realistic) paintings and photographs and rated how much they liked each one. Then they rated a similar set of images after receiving transcranial direct-current stimulation or sham stimulation. Transcranial direct-current stimulation sends small electrical impulses to the brain through electrodes attached to the head. The technique is noninvasive and cannot be felt, so subjects in the trials were not aware when they received real stimulation. The researchers aimed the impulses at the left dorsolateral prefrontal cortex, an area just behind the brow that is known to be a region critical for emotional processing. They found that the stimulation increased participants' appreciation of representational images, according to the study published online in October 2013 inSocial Cognitive and Affective Neuroscience. The scientists believe the stimulation facilitated a shift from object recognition to aesthetic appraisal for the figurative images; the abstract art was probably being processed by a different area of the brain. This study is one of many recent successful attempts at subtly altering cognition with noninvasive brain stimulation. Some experiments have found that stimulating certain areas allows people to solve math problems or puzzles that formerly had them stumped. Other work suggests these techniques can enhance motor learning, helping athletes or musicians improve at a new sport or a new instrument more rapidly. Experts are quick to point out, however, that these effects are modest enhancements at best—thought induction remains firmly in the realm of science fiction. © 2014 Scientific American
By Michelle Roberts Health editor, BBC News online Doctors have devised a new way to treat amputees with phantom limb pain. Using computer-generated augmented reality, the patient can see and move a virtual arm controlled by their stump. Electric signals from the muscles in the amputated limb "talk" to the computer, allowing real-time movement. Amputee Ture Johanson says his pain has reduced dramatically thanks to the new computer program, which he now uses regularly in his home. He now has periods when he is free of pain and he is no longer woken at night by intense periods of pain. Mr Johanson, who is 73 and lives in Sweden, lost half of his right arm in a car accident 48 years ago. After a below-elbow amputation he faced daily pain and discomfort emanating from his now missing arm and hand. Over the decades he has tried numerous therapies, including hypnosis, to no avail. Within weeks of starting on the augmented reality treatment in Max Ortiz Catalan's clinic at Chalmers University of Technology, his pain has now eased. "The pain is much less now. I still have it often but it is shorter, for only a few seconds where before it was for minutes. BBC © 2014
by Nathan Seppa Women who take acetaminophen during pregnancy are more likely to have a child with attention-deficit/hyperactivity disorder than are women who don’t, according to an analysis of nearly 41,000 pairs of mothers and children in a Danish birth registry. Researchers found that more than half of the women, who gave birth between 1996 and 2002, had used the pain reliever during pregnancy. Calls to the women when the children were 7 years old revealed that children whose moms used any acetaminophen during pregnancy were 37 percent more apt to be diagnosed with ADHD or a related disorder than children whose moms didn’t use the drug. If the women used it in all three trimesters, the apparent risk for offspring was 61 percent higher than for children whose mothers didn’t use the drug. Out of nearly 41,000 children, fewer than 1,000 were diagnosed with ADHD and related disorders. The data establish an association and not cause and effect. But the researchers note that acetaminophen, also sold as Tylenol or Panadol, can cross the placental barrier and may affect hormones in a fetus. Citations Z. Liew et al. Acetaminophen use during pregnancy, behavioral problems, and hyperkinetic disorders. JAMA Pediatrics. Online February 24, 2014. doi:10.1001/jamapediatrics.2013.4914. © Society for Science & the Public 2000 - 2013.
Sara Reardon Freddie Lee Hall loved to gamble, although he usually lost. Winning was better: then he gladly gave the money back to the friends he'd won it from, along with all the wages he earned picking fruit in rural Florida. His friends praised him for this. It made him feel good. And Hall needed to feel good — as court documents make abundantly clear. As a child growing up in the impoverished town of Webster, Florida, he had struggled to keep up with 16 brothers and sisters, who were much smarter than he was. If he failed to understand something, his mother beat him, once while he was tied up in a bag strung over a fire. He stuttered, never learned to read and feared the dark. He was unable to live alone. “Even though he was full grown, mentally he was a child,” his sister Diana told the court. “I had hoped to protect Freddie Lee from the outside world.” But the outside world found him. In 1978, Hall and his friend Mack Ruffin decided to rob a convenience store. They needed a car, so they forced 21-year-old Karol Hurst, who was pregnant, to drive into the woods, where they raped and killed her. Later, one of the pair also shot and killed a sheriff's deputy. When the two men were caught, tried and convicted of murder, the court decided that Hall was the likely ringleader. Ruffin was eventually sentenced to life in prison; Hall was sentenced to death. Next month, after 35 years of failed appeals to have that death sentence commuted to life imprisonment, Hall will have his case heard before the US Supreme Court. His guilt is not in question: the issue is Florida's use of IQ test scores in sentencing him to death. © 2014 Nature Publishing Group,
By ALAN SCHWARZ Jerry, 9 years old, dissolved into his Game Boy while his father described his attentional difficulties to the family pediatrician. The child began flitting around the room distractedly, ignoring the doctor’s questions and squirming in his chair — but then he leapt up and yelled: “Freeze! What do you think is the problem here?” Nine-year-old Jerry was in fact being played by Dr. Peter Jensen, one of the nation’s most prominent child psychiatrists. On this Sunday in January in New York, Dr. Jensen was on a cross-country tour, teaching pediatricians and other medical providers how to properly evaluate children’s mental health issues — especially attention deficit hyperactivity disorder, which some doctors diagnose despite having little professional training. One in seven children in the United States — and almost 20 percent of all boys — receives a diagnosis of A.D.H.D. by the time they turn 18, according to the Centers for Disease Control and Prevention. It narrowly trails asthma as the most common long-term medical condition in children. Increasing concern about the handling of the disorder has raised questions about the training doctors receive before diagnosing the condition and prescribing stimulants like Adderall or Concerta, sometimes with little understanding of the risks. The medications can cause sleep problems, loss of appetite and, in rare cases, delusions. Because the disorder became a widespread national health concern only in the past few decades, many current pediatricians received little formal instruction on it, sometimes only several hours, during their seven years of medical school and residency. But the national scarcity of child psychiatrists has placed much of the burden for evaluating children’s behavioral problems on general pediatricians and family doctors, a reality that Dr. Jensen and others are trying to address through classes that emphasize role-playing exercises and spirited debate. © 2014 The New York Times Company
by Bethany Brookshire CHIGAGO – From a cockatoo bopping to the Backstreet Boys to a sea lion doing the boogie, nothing goes viral like an animal swaying to the music. Now, research shows that not only can bonobos feel the beat, they can play along. Music “engages the brain in a way that no other stimulus can,” says cognitive psychologist Edward Large of the University of Connecticut in Storrs. He and Patricia Gray, a biomusic researcher at the University of North Carolina at Greensboro, wanted to see if bonobos, which share 98.7 percent of their DNA with humans, might respond similarly to musical rhythms. The researchers gave a group of bonobos access to a specially tailored drum, then showed them people drumming rhythmically. Eventually three animals picked up the beat and were able to match tempos with the scientists. Bonobos were also found to prefer a faster pace than most people. Large and Gray presented their findings February 15 at the American Association for the Advancement of Science annual meeting. Rhythm involves the coordination of many brain areas, such as auditory and motor regions. Further research could help scientists understand whether only a few species can keep the beat, or if moving to the groove is widespread in the animal kingdom. © Society for Science & the Public 2000 - 2013.
Kids with ADHD may be able to learn better focus through a computer game that trains the brain to pay attention, a new study suggests. The game was part of a neurofeedback system that used bicycle helmets wired to measure brain waves and gave immediate feedback when kids were paying attention, researchers reported Monday in Pediatrics. Giving kids feedback on what their brains are doing is "like turning on a light switch," said Dr. Naomi Steiner, the study's lead author and a developmental and behavioral pediatrician at the Floating Hospital for Children at Tufts Medical Center. "Kids said 'Oh, this is what people mean when they tell me to pay attention.'" To test the system, Steiner and her colleagues randomly assigned 104 Boston area elementary school children to one of three groups: no treatment, 40 half-hour sessions of neurofeedback or 40 sessions of cognitive therapy. The kids getting neurofeedback wore standard bicycle helmets fitted with brain wave sensors while they performed a variety of exercises on the computer. In one exercise, kids were told to focus on a cartoon dolphin. When people pay attention, theta wave activity goes down while beta waves increase, Steiner explained. If the kids' brains showed they were paying attention, the dolphin would dive to the bottom of the sea. Parents' reports on ADHD symptoms six months later showed a lasting improvement in kids who had done neurofeedback.
Carl Zimmer In 2011, a 66-year-old retired math teacher walked into a London neurological clinic hoping to get some answers. A few years earlier, she explained to the doctors, she had heard someone playing a piano outside her house. But then she realized there was no piano. The phantom piano played longer and longer melodies, like passages from Rachmaninov’s Piano Concerto number 2 in C minor, her doctors recount in a recent study in the journal Cortex. By the time the woman — to whom the doctors refer only by her first name, Sylvia — came to the clinic, the music had become her nearly constant companion. Sylvia hoped the doctors could explain to her what was going on. Sylvia was experiencing a mysterious condition known as musical hallucinations. These are not pop songs that get stuck in your head. A musical hallucination can convince people there is a marching band in the next room, or a full church choir. Nor are musical hallucinations the symptoms of psychosis. People with musical hallucinations usually are psychologically normal — except for the songs they are sure someone is playing. The doctors invited Sylvia to volunteer for a study to better understand the condition. She agreed, and the research turned out to be an important step forward in understanding musical hallucinations. The scientists were able to compare her brain activity when she was experiencing hallucinations that were both quiet and loud — something that had never been done before. By comparing the two states, they found important clues to how the brain generates these illusions. If a broader study supports the initial findings, it could do more than help scientists understand how the brain falls prey to these phantom tunes. It may also shed light on how our minds make sense of the world. © 2014 The New York Times Company
Katherine Sharpe Ben Harkless could not sit still. At home, the athletic ten-year-old preferred doing three activities at once: playing with his iPad, say, while watching television and rolling on an exercise ball. Sometimes he kicked the walls; other times, he literally bounced off them. School was another story, however. Ben sat in class most days with his head down on his desk, “a defeated heap”, remembers his mother, Suzanne Harkless, a social worker in Berkeley, California. His grades were poor, and his teacher was at a loss for what to do. Harkless took Ben to a therapist who diagnosed him with attention deficit hyperactivity disorder (ADHD). He was prescribed methylphenidate, a stimulant used to improve focus in people with the condition. Harkless was reluctant to medicate her child, so she gave him a dose on a morning when she could visit the school to observe. “He didn't whip through his work, but he finished his work,” she says. “And then he went on and helped his classmate next to him. My jaw dropped.” ADHD diagnoses are rising rapidly around the world and especially in the United States, where 11% of children aged between 4 and 17 years old have been diagnosed with the disorder. Between half and two-thirds of those are put on medication, a decision often influenced by a child's difficulties at school. And there are numerous reports of adolescents and young adults without ADHD using the drugs as study aids. © 2014 Nature Publishing Group,